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LimeSDR-QPCIe v1.2 hardware description

1 Introduction

LimeSDR-QPCIe is low-cost software defined radio board based on Lime LMS7002M Field Programmable Radio Frequency (FPRF) transceiver and Altera Cyclone V PFGA, through which apps can be programmed to support any type of wireless standard, e.g. UMTS, LTE, LoRa, GPS, WiFi, Zigbee, RFID, Digital Broadcastimng, Radar and many more.

2 LimeSDR-QPCIe Board Key Features

The LimeSDR-QPCIe development board provides a hardware platform for developing and prototyping high-performance and logic-intensive digital and RF designs using Altera’s Cyclone V FPGA and Lime Microsystems transceiver.

Figure 1. LimeSDR-QPCIe v1.2 board


For more information on the following topics, refer to the respective documents:

  • Cyclone V device family, refer to Cyclone V Device support resources link
  • LMS7002M transceiver resources link


LimeSDR-QPCIe v1.2 board features:

  • USB Interface
    • Cypress FX3 Super Speed USB 3rd generation controller
  • FPGA Features
    • Cyclone V, 5CGXFC7D7F31C8N device in 896-pin FBGA package
    • 150’000 logic elements
    • 6860 Kbits embedded memory
    • 312 embedded 18x18 multipliers
    • 7 PLLs
    • 9 Transceivers (2.5Gbps)
    • PCIe Hard IP Blocks
    • 2 Hard Memory Controllers
  • FPGA Configuration
    • JTAG mode configuration
    • Active serial mode configuration
    • Possibility to update FPGA gateware by using FX3 (USB)
    • Possibility to update FPGA gateware by using PCIe interface.
  • RF
    • 2x LMS7002M, FPRF transceivers
    • Onboard RSSI measurement circuits
    • Onboard loopback control switches
  • DACs and ADCs
    • 2x DAC5672A, dual, 14-bit, Digital-To-Analog converters
    • 1x ADS424, Dual-Channel, 14-bit, Analog-To-Digital converter
  • Memory Devices
    • 4 x 2Gbit DDR3 SDRAM (128M x 16)
    • 4Mbit flash for FX3 firmware
    • 128Mbit flash for FPGA gateware
    • 2 x 128Kbit and 2 x 512Kbit EEPROMs for LMS MCU firmware, LMS MCU data
    • 1 x 128K EEPROM for FX3 or FPGA data
  • Connections
    • microUSB3.0 (type B) connector
    • PCIe x4 edge connector (Gen1)
    • Coaxial RF (U.FL) connectors
    • 2x PMOD header (0.1” pitch)
    • FPGA (0.1” pitch) and FX3 (0.05” pitch) JTAG connectors
    • 12V DC power jack and pinheader
    • LVDS connector (0.05” pitch)
    • Fan connector (12V/5V)
    • PCIe 6-pin power connector
    • Holder for coin cell CR1220 battery
  • Clock System
    • 30.72MHz VCTCXO (precision: ±1 ppm initial, ±4 ppm stable).
    • Possibility to lock VCTCXO to external clock using ADF4002 or tune VCTCXO by onboard DAC (AD5662)
    • Programmable clock generator for the FPGA reference clock input or LMS PLLs
    • VCTCXO clock output for external device synchronization.
    • 1x 100 MHz, 4 x 125MHz crystal oscillators for FPGA
  • Miscellaneous devices
    • LM75 Digital temperature sensor with 2-Wire Interface.
    • DS3231 real-time clock.
    • M0578-A3 GPS/GNSS module receiver
  • Board Size 190mm x 106.7mm (7.48” x 4.20”)

2.1 LimeSDR-QPCIe Board Overview

LimeSDR-QPCIe board version 1.2 picture with highlighted major connectors presented in Figure 2. There are three connector types – data and debugging (PCIe, USB3.0, PMOD, LVDS and JTAG), power (DC jack and external supply pinheaders) and high frequency (RF and reference clock).

Figure 2 LimeSDR-QPCIe v1.2 Development Board Connectors


Board components description listed in the Table 1.

Table 1. Board components
Featured Devices
Board Reference Type Description
IC1, IC2 FPRF Field programmable RF transceivers LMS7002M
IC8 FPGA Altera Cyclone V GX, 5CGXFC7D7F31C8N, 896-BGA
IC13 USB3.0 microcontroller Cypress FX3 Supper Speed USB 3rd generation controller CYUSB3013
Miscellaneous devices on board
IC7, IC8 IC 8-bit shift registers 74HC595BQ,115
IC9, IC49 IC Bidirectional voltage shifters SN74AVC4T774RSVR
IC10, IC11, IC12, IC13, IC14, IC15, IC16, IC17 IC 100MHz – 3 GHz SPDT RF switches SKY13323-378LF
IC18, IC20, IC23, IC25, IC26, IC28 IC 12-bit ADCs MAX11108AVB+T
IC19, IC24, IC27 IC 1MHz–10GHz dual log detector/controller ADL5519
IC22 IC SP4T RF switch PE42442A-Z
IC31 IC 4 parallel 2:1 switches TS3A5018PWR
IC37 IC 14-bit 2-channel ADC ADS4246IRGCT
IC38 IC Dual differential amplifier ADA4930
IC39, IC56 IC Differential line drivers SN65LVDS1DBVR
IC40, IC41 IC Dual differential DACs DAC5672AIPFB
IC44, IC45 IC Bidirectional 8-channel voltage translators FXLA108BQX
IC47 IC Temperature sensor LM75
IC48 IC GPS receiver module M10578-A3
IC50 IC Real time clock (RTC) DS3231S#
BATT1 Holder Holder for coin cell CR1220 battery
ESD26 TVS USB3.0 ESD protection TVS diode
ESD1, ESD2, ESD3, ESD4, ESD5, ESD6, ESD7, ESD8, ESD9, ESD10, ESD11, ESD12, ESD13, ESD14, ESD15, ESD16, ESD17, ESD18, ESD19, ESD20, ESD21, ESD22, ESD23, ESD24, ESD25 TVS RF connector ESD protection TVS diodes
Configuration, Status and Setup Components
R56, R57, R58, R59 0 Ohm resistor Board BOM version BOM_VER[3:0]. Default BOM_VER=0 (all resistors populated).
R160, R161, R163, R164, R166, R167, R168, R169, R171, R172 0 Ohm resistor FPGA (IC8) MSEL[3:0]. Default mode: Active Serial Standard configuration.
[R268, R271, R275, R279], [R269, R273, R277, R281] 0 Ohm resistor DAC#1 differential channels TX1_BB_I/Q connection selection to either LMS7002M #1 or LMS7002M #2. Default populated group is [R268, R271, R275, R279]. Resistor groups are defined in [] brackets.
[R270, R274, R278, R282], [R272, R276, R280, R283] 0 Ohm resistor DAC#2 differential channels TX2_BB_I/Q connection selection to either LMS7002M #1 or LMS7002M #2. Default populated group is [R270, R274, R278, R282]. Resistor groups are defined in [] brackets.
R364, R379, R384 and their respective power connecting resistors R365, R380, R382 0 Ohm resistor Clock buffer (IC52) CLKin0 (pin 13) clock source selection. R364 and R365 are populated by default.
R368, R372, R374 0 Ohm resistor Clock buffer (IC52) CLKin1 (pin 28) clock source selection. R374 is populated by default.
R375 0 Ohm resistor Clock buffer (IC52) source (CLKin0 or CLKin1) selection. If unpopulated, clock source is CLKin0 (default). If populated, clock source is CLKin1.
R302, R305, R307 10 kOhm resistor USB3.0 microcontroller (IC13) boot configuration (PMODE0[2:0]) resistors. Default mode: SPI boot, On Failure - USB Boot
R294, R296, R298 10 kOhm resistor USB3.0 microcontroller (IC13) crystal/clock frequency selection (FSLC[2:0]) resistors. Default mode: 19.2MHz crystal
J28, R313 Pin header, 0 Ohm resistor USB3.0 microcontroller (IC13) boot source (Flash memory or USB), 0.1” pitch jumper or 0402 0R resistor. In normal operation jumper or resistor must be placed.
J29 JTAG chain pin header USB3.0 microcontroller (IC13) debugging pin header, 0.05” pitch
SW1 Push-button USB3.0 microcontroller reset button
J26 JTAG chain pin header FPGA programming pin header for Altera USB-Blaster download cable, 0.1” pitch
LED1 Green status LED FPGA configuration done LED
LED2-LED5 Green status LEDs User defined general purpose green LEDs
LED6 Red-green status LED User defined general purpose dual colour LED
General User Input/Output
J31, J32 Connector 0.1” PMOD connectors
SW2 Switch 4-bit FPGA switch
J33 Pin header Board cooling fan pin header, 0.1”
Memory Devices
IC3, IC5, IC51 EEPROM 128Kbit (16K x 8) EEPROM, LMS7002 MCU firmware and general purpose memory
IC4, IC6 EEPROM 512Kbit (64K x 8) EEPROM, connected to main I2C bus
IC30 Flash memory 128Mbit (16M x 8) Flash for FPGA configuration (unpopulated)
IC32 Flash memory 128Mbit (16M x 8) Flash for FPGA configuration
IC33, IC34, IC35, IC36 DDR3 memory 2Gbit (128M x 16) DDR3 SDRAM
Communication Ports
J27 USB3.0 connector microUSB3.0 (type B) connector
P1 PCIe connector PCI Express (Gen1) x4 connector
Clock Circuitry
XO1 VCOCXO 10MHz voltage- and oven-controlled crystal oscillator
XO2, XO3 VCTCXO 30.72MHz voltage-controlled crystal oscillator
XO4 VCTCXO 40MHz voltage-controlled crystal oscillator
IC57 IC Programmable clock generator for the FPGA reference clock input and RF boards
IC53 IC ADF4002 phase detector
IC54 IC 16-bit DAC for VCTCXO/VCOCXO frequency tuning
IC52 IC Clock buffer
IC55 IC Clock buffer
J36 U.FL connector Reference clock input
J35 U.FL connector Reference clock output
XO5 Crystal oscillator 100MHz single-ended FPGA clock
XO6 Crystal oscillator 125MHz single-ended FPGA clock
XO7 Crystal oscillator 125MHz differential FPGA-DDR clock
XO8 Crystal oscillator 125MHz differential FPGA-DDR clock
XO9 Crystal oscillator 125MHz differential FPGA clock for PCIe REFCLK1
IC56 IC Single-ended to differential clock converter. Clock source is IC57 pin 9. Connected to FPGA PCIe REFCLK2 and LVDS connector J30.
Power Supply
J37 DC input jack External 12V DC power supply
J38 Header 6-pin PCIe power connector, 0.165” pitch
J39 Pin header External 12V DC power supply and main internal power rail

LimeSDR-QPCIe board version 1.2 picture with highlighted top components are presented in Figure 3.

Figure 3 LimeSDR-QPCIe Development Board Top Components


LimeSDR-QPCIe board version 1.2 picture with highlighted bottom components is presented in Figure 4.

Figure 4 LimeSDR-QPCIe Development Board Bottom Components

2.2 LimeSDR-QPCIe Board Architecture

The heart of the LimeSDR-QPCIe board is Altera Cyclone V GX FPGA. Its main function is to transfer digital data between the PC through an edge PCIE and a USB3.0 connector. The block diagram for LimeSDR-QPCIe board is presented in the Figure 5.

Figure 5 LimeSDR-QPCIe v1.2 Block Diagram

2.2.1 FPGA configuration

FPGA is set to use x1 Active Serial (AS) configuration scheme. In this scheme if valid configuration file exists in FLASH memory (IC30 or IC32) it is automatically loaded after power is applied to the board. In Table 2 it is listed resistor setup for Active Serial (AS) configuration mode select.

Table 2 FPGA configuration setup (AS)
Schematic signal name Logic level 0R Resistor setup
MSEL0 H R160 (NF) R161 (Fit)
MSEL1 H R163 (NF) R164 (Fit)
MSEL2 L R166 (Fit) R167 (NF)
MSEL3 L R168 (Fit) R169 (NF)
MSEL4 H R171 (NF) R172 (Fit)

There are two options which allows to change configuration file in FLASH memory:

  • USB 3.0 controller – CYUSB3013 (IC42) has access to configuration memory. With valid firmware and software, gateware for FPGA can be uploaded into FLASH memory (IC30 or IC32) by using USB3.0 cable. IC42 can initiate FPGA reconfiguration. For signal interconnect details see chapter 2.2.2.3 USB 3.0 Controller.
  • JTAG Header – 10pin connector (J26) provides access to FPGA JTAG chain. By using external download cable such as USB-Blaster and Quartus II Programmer software FLASH memory (IC30 or IC32) can be reprogrammed. JTAG connections are listed in Table 3.
Table 3 JTAG header (J26)
Connector pin Schematic signal name FPGA pin (IC29) Comment
1 FPGA_JTAG_TCK AC7 R170 Pull-Down resistor
2 VCC2P5 -
3 FPGA_JTAG_TDO W9
4 VCC2P5 -
5 FPGA_JTAG_TMS V7 R162 Pull-Up resistor
6 - -
7 - -
8 - -
9 FPGA_JTAG_TDI U7 R165 Pull-Up resistor
10 GND -

2.2.2 Main components

This chapter describes main components mounted on LimeSDR-QPCIe v1.2 board.

2.2.2.1 LMS7002M RF transceiver

There are two LMS7002M field programmable RF transceiver ICs (LMS7002M#1 - IC1 and LMS7002M#1 - IC2), interface signals can be acknowledged by corresponding names LMSx_*, where x can be 1 or 2. For example LMS1_* signals belongs to IC1 and LMS2_* belongs to IC2.

In the following manner interface and control signals are described below:

  • Digital Interface Signals: LMS7002 is using data bus LMSx_DIQ1_D[11:0] and LMSx_DIQ2_D[11:0], LMSx_ENABLE_IQSEL1 and LMSx_ENABLE_IQSEL2, LMSx_FCLK1 and LMSx_FCLK2, LMSx_MCLK1 and LMSx_MCLK2 signals to transfer data to/from FPGA. Indexes 1 and 2 indicate transceiver digital data PORT-1 or PORT-2. Any of these ports can be used to transmit or receive data. By default, PORT-1 is selected as receive port and PORT-2 is selected as transmit port. The FCLK# is input clock and MCLK# is output clock for LMS7002M transceiver. TXNRX signals sets ports directions. For LMS7002M interface timing details refer to LMS7002M transceiver datasheet page 12-13 [1].
  • LMS Control Signals: these signals are used for optional functionality:
    • LMSx_RXEN, LMSx_TXEN – receiver and transmitter enable/disable signals.
    • LMS_RESET – LMS7002M reset signal.
  • SPI Interface: LMS7002M transceiver is configured via 4-wire SPI interface; FPGA_SPI0_SCLK, FPGA_SPI0_MOSI, FPGA_SPI0_MISO_LMSx, FPGA_SPI0_LMSx_SS. The SPI interface controlled from FPGA.
  • LMS I2C Interface: LMS EEPROM are connected to this interface. The signals LMSx_I2C_SCL, LMSx_I2C_DATA is not connected to FPGA


The Table 4 and Table 5below lists RF transceiver respectively LMS7002#1 and LMS7002#2 pins, schematic signal names, FPGA interconnections and I/O standard.

Table 4 RF transceiver (LMS7002M#1) digital interface pins
Chip pin (IC1) Chip reference (IC1) Schematic signal name FPGA pin FPGA I/O standard Comments
AM24 xoscin_rx LMS1_RxPLL_CLK NC 3.3V Connected to 30.72 MHz clock
P34 MCLK2 LMS1_MCLK2 U21 2.5V/3.3V
R29 FCLK2 LMS1_FCLK2 Y22 2.5V/3.3V
U31 TXNRX2 LMS1_TXNRX2 U26 2.5V/3.3V
V34 RXEN LMS1_RXEN Y26 2.5V/3.3V
R33 ENABLE_IQSEL2 LMS1_ENABLE_IQSEL2 AA26 2.5V/3.3V
H30 DIQ2_D0 LMS1_DIQ2_D0 AC27 2.5V/3.3V
J31 DIQ2_D1 LMS1_DIQ2_D1 AB27 2.5V/3.3V
K30 DIQ2_D2 LMS1_DIQ2_D2 Y21 2.5V/3.3V
K32 DIQ2_D3 LMS1_DIQ2_D3 AA29 2.5V/3.3V
L31 DIQ2_D4 LMS1_DIQ2_D4 Y28 2.5V/3.3V
K34 DIQ2_D5 LMS1_DIQ2_D5 AC26 2.5V/3.3V
M30 DIQ2_D6 LMS1_DIQ2_D6 W27 2.5V/3.3V
M32 DIQ2_D7 LMS1_DIQ2_D7 AA25 2.5V/3.3V
N31 DIQ2_D8 LMS1_DIQ2_D8 V26 2.5V/3.3V
N33 DIQ2_D9 LMS1_DIQ2_D9 AH29 2.5V/3.3V
P30 DIQ2_D10 LMS1_DIQ2_D10 V27 2.5V/3.3V
P32 DIQ2_D11 LMS1_DIQ2_D11 W28 2.5V/3.3V
E5 xoscin_tx LMS1_TxPLL_CLK NC 3.3V Connected to 30.72 MHz clock
AB34 MCLK1 LMS1_MCLK1 U22 2.5V/3.3V
AA33 FCLK1 LMS1_FCLK1 Y30 2.5V/3.3V
V32 TXNRX1 LMS1_TXNRX1 U27 2.5V/3.3V
U29 TXEN LMS1_TXEN V21 2.5V/3.3V
Y32 ENABLE_IQSEL1 LMS1_ENABLE_IQSEL1 U28 2.5V/3.3V
AG31 DIQ1_D0 LMS1_DIQ1_D0 T28 2.5V/3.3V
AF30 DIQ1_D1 LMS1_DIQ1_D1 Y23 2.5V/3.3V
AF34 DIQ1_D2 LMS1_DIQ1_D2 AB28 2.5V/3.3V
AE31 DIQ1_D3 LMS1_DIQ1_D3 T29 2.5V/3.3V
AD30 DIQ1_D4 LMS1_DIQ1_D4 AA23 2.5V/3.3V
AC29 DIQ1_D5 LMS1_DIQ1_D5 V22 2.5V/3.3V
AE33 DIQ1_D6 LMS1_DIQ1_D6 V24 2.5V/3.3V
AD32 DIQ1_D7 LMS1_DIQ1_D7 Y27 2.5V/3.3V
AC31 DIQ1_D8 LMS1_DIQ1_D8 AC24 2.5V/3.3V
AC33 DIQ1_D9 LMS1_DIQ1_D9 V25 2.5V/3.3V
AB30 DIQ1_D10 LMS1_DIQ1_D10 W22 2.5V/3.3V
AB32 DIQ1_D11 LMS1_DIQ1_D11 AA24 2.5V/3.3V
U33 CORE_LDO_EN LMS1_CORE_LDO_EN Y25 2.5V/3.3V
E27 RESET LMS1_RESET L21 2.5V/3.3V
D28 SEN FPGA_SPI0_LMS1_SS V29 2.5V/3.3V SPI interface
C29 SCLK FPGA_SPI0_SCLK T25 2.5V/3.3V SPI interface
F30 SDIO FPGA_SPI0_MOSI R26 2.5V/3.3V SPI interface
F28 SDO FPGA_SPI0_MISO_LMS1 R30 2.5V/3.3V SPI interface
D26 SDA LMS1_I2C_SDA - 2.5V Connected to EEPROM
C27 SCL LMS1_I2C_SCL - 2.5V Connected to EEPROM

AM24 ||xoscin_rx ||LMS2_RxPLL_CLK ||NC ||3.3V ||Connected to 30.72 MHz clock

Table 5 RF transceiver (LMS7002M#2) digital interface pins
Chip pin (IC2) Chip reference (IC2) Schematic signal name FPGA pin FPGA I/O standard Comments
P34 MCLK2 LMS2_MCLK2 U23 2.5V/3.3V
R29 FCLK2 LMS2_FCLK2 AC29 2.5V/3.3V
U31 TXNRX2 LMS2_TXNRX2 AC30 2.5V/3.3V
V34 RXEN LMS2_RXEN AE25 2.5V/3.3V
R33 ENABLE_IQSEL2 LMS2_ENABLE_IQSEL2 AF25 2.5V/3.3V
H30 DIQ2_D0 LMS2_DIQ2_D0 AA28 2.5V/3.3V
J31 DIQ2_D1 LMS2_DIQ2_D1 AJ30 2.5V/3.3V
K30 DIQ2_D2 LMS2_DIQ2_D2 AB29 2.5V/3.3V
K32 DIQ2_D3 LMS2_DIQ2_D3 AD24 2.5V/3.3V
L31 DIQ2_D4 LMS2_DIQ2_D4 AG28 2.5V/3.3V
K34 DIQ2_D5 LMS2_DIQ2_D5 AG27 2.5V/3.3V
M30 DIQ2_D6 LMS2_DIQ2_D6 AB26 2.5V/3.3V
M32 DIQ2_D7 LMS2_DIQ2_D7 AF24 2.5V/3.3V
N31 DIQ2_D8 LMS2_DIQ2_D8 AH30 2.5V/3.3V
N33 DIQ2_D9 LMS2_DIQ2_D9 AE23 2.5V/3.3V
P30 DIQ2_D10 LMS2_DIQ2_D10 AG29 2.5V/3.3V
P32 DIQ2_D11 LMS2_DIQ2_D11 AE26 2.5V/3.3V
E5 xoscin_tx LMS2_TxPLL_CLK NC 3.3V Connected to 30.72 MHz clock
AB34 MCLK1 LMS2_MCLK1 T24 2.5V/3.3V
AA33 FCLK1 LMS2_FCLK1 W30 2.5V/3.3V
V32 TXNRX1 LMS2_TXNRX1 AF28 2.5V/3.3V
U29 TXEN LMS2_TXEN AD27 2.5V/3.3V
Y32 ENABLE_IQSEL1 LMS2_ENABLE_IQSEL1 AF29 2.5V/3.3V
AG31 DIQ1_D0 LMS2_DIQ1_D0 AD25 2.5V/3.3V
AF30 DIQ1_D1 LMS2_DIQ1_D1 AD29 2.5V/3.3V
AF34 DIQ1_D2 LMS2_DIQ1_D2 AH27 2.5V/3.3V
AE31 DIQ1_D3 LMS2_DIQ1_D3 AE30 2.5V/3.3V
AD30 DIQ1_D4 LMS2_DIQ1_D4 AE28 2.5V/3.3V
AC29 DIQ1_D5 LMS2_DIQ1_D5 AD30 2.5V/3.3V
AE33 DIQ1_D6 LMS2_DIQ1_D6 AJ28 2.5V/3.3V
AD32 DIQ1_D7 LMS2_DIQ1_D7 AF26 2.5V/3.3V
AC31 DIQ1_D8 LMS2_DIQ1_D8 AE27 2.5V/3.3V
AC33 DIQ1_D9 LMS2_DIQ1_D9 AJ29 2.5V/3.3V
AB30 DIQ1_D10 LMS2_DIQ1_D10 AD28 2.5V/3.3V
AB32 DIQ1_D11 LMS2_DIQ1_D11 AF30 2.5V/3.3V
U33 CORE_LDO_EN LMS2_CORE_LDO_EN AD23 2.5V/3.3V
E27 RESET LMS2_RESET AA30 2.5V/3.3V
D28 SEN FPGA_SPI0_LMS2_SS U29 2.5V/3.3V SPI interface
C29 SCLK FPGA_SPI0_SCLK T25 2.5V/3.3V SPI interface
F30 SDIO FPGA_SPI0_MOSI R26 2.5V/3.3V SPI interface
F28 SDO FPGA_SPI0_MISO_LMS2 V30 2.5V/3.3V SPI interface
D26 SDA LMS2_I2C_SDA - 2.5V Connected to EEPROM
C27 SCL LMS2_I2C_SCL - 2.5V Connected to EEPROM
2.2.2.2 SDRAM

LimeSDR-QPCIe board has four 2Gb DDR3 SDRAM memory ICs (AS4C128M16D3B-12BCN [link]) which are connected to Cyclone V GX FPGA. The memory can be used for data manipulation at high data rates between transceiver and FPGA. There are two independent DDR3 SDRAM interfaces:

  • DDR3 TOP – this is 32bit data interface which consist of two x16 memory devices (IC33 AND IC34) with a single address and command bus. Interface is connected to FPGA Bank 7A and 8A and uses hard memory controller. Error! Reference source not found. lists DDR3 TOP interface pins.
  • DDR3 BOT – this is 32bit data interface which consist of two x16 memory devices (IC35 AND IC36) with a single address and command bus. Interface is connected to FPGA Bank 3B and 4A and uses hard memory controller. lists DDR3 BOT interface pins.


Following Table 6 lists signal and pin information for DDR3 TOP interface and Table 7 for the DDR3 BOT interface.

Table 6 DDR3 TOP interface pins
RAM reference RAM pin Schematic signal name FPGA pin (IC29) FPGA I/O standard Comments
Address bus (IC33 and IC34 shared signals)
A0 N3 DDR3_TOP_A0 B11 SSTL-15 Class I Active termination
A1 P7 DDR3_TOP_A1 A11 SSTL-15 Class I Active termination
A2 P3 DDR3_TOP_A2 F9 SSTL-15 Class I Active termination
A3 N2 DDR3_TOP_A3 E10 SSTL-15 Class I Active termination
A4 P8 DDR3_TOP_A4 F16 SSTL-15 Class I Active termination
A5 P2 DDR3_TOP_A5 E16 SSTL-15 Class I Active termination
A6 R8 DDR3_TOP_A6 D9 SSTL-15 Class I Active termination
A7 R2 DDR3_TOP_A7 C10 SSTL-15 Class I Active termination
A8 T8 DDR3_TOP_A8 E12 SSTL-15 Class I Active termination
A9 R3 DDR3_TOP_A9 D13 SSTL-15 Class I Active termination
A10/AP L7 DDR3_TOP_A10 B7 SSTL-15 Class I Active termination
A11 R7 DDR3_TOP_A11 A8 SSTL-15 Class I Active termination
A12/BC# N7 DDR3_TOP_A12 B6 SSTL-15 Class I Active termination
A13 T3 DDR3_TOP_A13 A6 SSTL-15 Class I Active termination
Bank address bus (IC33 and IC34 shared signals)
BA0 M2 DDR3_TOP_BA0 A10 SSTL-15 Class I Active termination
BA1 N8 DDR3_TOP_BA1 F15 SSTL-15 Class I Active termination
BA2 M3 DDR3_TOP_BA2 E15 SSTL-15 Class I Active termination
Data bus [0:15] (IC33)
DQ0 E3 DDR3_TOP_DQ0 C15 SSTL-15 Class I
DQ1 F7 DDR3_TOP_DQ1 C16 SSTL-15 Class I
DQ2 F2 DDR3_TOP_DQ2 C11 SSTL-15 Class I
DQ3 F8 DDR3_TOP_DQ3 A13 SSTL-15 Class I
DQ4 H3 DDR3_TOP_DQ4 D17 SSTL-15 Class I
DQ5 H8 DDR3_TOP_DQ5 E17 SSTL-15 Class I
DQ6 G2 DDR3_TOP_DQ6 D12 SSTL-15 Class I
DQ7 H7 DDR3_TOP_DQ7 A14 SSTL-15 Class I
DQ8 D7 DDR3_TOP_DQ8 B17 SSTL-15 Class I
DQ9 C3 DDR3_TOP_DQ9 C17 SSTL-15 Class I
DQ10 C8 DDR3_TOP_DQ10 A16 SSTL-15 Class I
DQ11 C2 DDR3_TOP_DQ11 C14 SSTL-15 Class I
DQ12 A7 DDR3_TOP_DQ12 F18 SSTL-15 Class I
DQ13 A2 DDR3_TOP_DQ13 G18 SSTL-15 Class I
DQ14 B8 DDR3_TOP_DQ14 B18 SSTL-15 Class I
DQ15 A3 DDR3_TOP_DQ15 A19 SSTL-15 Class I
Data bus [16:31] (IC34)
DQ0 E3 DDR3_TOP_DQ16 D18 SSTL-15 Class I
DQ1 F7 DDR3_TOP_DQ17 D19 SSTL-15 Class I
DQ2 F2 DDR3_TOP_DQ18 A21 SSTL-15 Class I
DQ3 F8 DDR3_TOP_DQ19 B21 SSTL-15 Class I
DQ4 H3 DDR3_TOP_DQ20 E18 SSTL-15 Class I
DQ5 H8 DDR3_TOP_DQ21 F19 SSTL-15 Class I
DQ6 G2 DDR3_TOP_DQ22 B23 SSTL-15 Class I
DQ7 H7 DDR3_TOP_DQ23 B24 SSTL-15 Class I
DQ8 D7 DDR3_TOP_DQ24 C19 SSTL-15 Class I
DQ9 C3 DDR3_TOP_DQ25 D20 SSTL-15 Class I
DQ10 C8 DDR3_TOP_DQ26 A25 SSTL-15 Class I
DQ11 C2 DDR3_TOP_DQ27 D22 SSTL-15 Class I
DQ12 A7 DDR3_TOP_DQ28 C20 SSTL-15 Class I
DQ13 A2 DDR3_TOP_DQ29 C21 SSTL-15 Class I
DQ14 B8 DDR3_TOP_DQ30 D23 SSTL-15 Class I
DQ15 A3 DDR3_TOP_DQ31 C25 SSTL-15 Class I
Data mask[0:1] (IC33)
LDM E7 DDR3_TOP_DM0 B14 SSTL-15 Class I
UDM D3 DDR3_TOP_DM1 B19 SSTL-15 Class I
Data mask[2:3] (IC34)
LDM E7 DDR3_TOP_DM2 C24 SSTL-15 Class I
UDM D3 DDR3_TOP_DM3 D25 SSTL-15 Class I
Data strobe[0:1] (IC33)
LDQS G3 DDR3_TOP_DQS0_P K17 Differential 1.5-V SSTL Class I
LDQS# F3 DDR3_TOP_DQS0_N J17 Differential 1.5-V SSTL Class I
UDQS C7 DDR3_TOP_DQS1_P K16 Differential 1.5-V SSTL Class I
UDQS# B7 DDR3_TOP_DQS1_N L16 Differential 1.5-V SSTL Class I
Data strobe[2:3] (IC34)
LDQS G3 DDR3_TOP_DQS2_P L18 Differential 1.5-V SSTL Class I
LDQS# F3 DDR3_TOP_DQS2_N K18 Differential 1.5-V SSTL Class I
UDQS C7 DDR3_TOP_DQS3_P K20 Differential 1.5-V SSTL Class I
UDQS# B7 DDR3_TOP_DQS3_N J19 Differential 1.5-V SSTL Class I
Memory clock (IC33 and IC34 shared signals)
CK# K7 DDR3_TOP_CK_N M8 Differential 1.5-V SSTL Class I
CK J7 DDR3_TOP_CK_P M9 Differential 1.5-V SSTL Class I
Control signals(IC33 and IC34 shared signals)
CKE K9 DDR3_TOP_CKE A18 SSTL-15 Class I
WE# L3 DDR3_TOP_WEn C7 SSTL-15 Class I Active termination
CAS# K3 DDR3_TOP_CASn C9 SSTL-15 Class I Active termination
RAS# J3 DDR3_TOP_RASn B8 SSTL-15 Class I Active termination
CS# L2 DDR3_TOP_CSn J15 SSTL-15 Class I Active termination
ODT K1 DDR3_TOP_ODT B13 SSTL-15 Class I Active termination
RESET# T2 DDR3_TOP_RESETn B22 1.5V Active termination
VREF (IC33 and IC34 shared signals)
VREFDQ H1 VREF_DDR3_TOP -
VREFCA M8 VREF_DDR3_TOP -
Memory ZQ impedance calibration (IC33)
ZQ L8 DDR3_TOP_RZQ0 -
Memory ZQ impedance calibration (IC34)
ZQ L8 DDR3_TOP_RZQ1 -
FPGA OCT calibration pin
- - OCT_RZQIN1 B12 SSTL-15
Table 7 DDR3 BOT interface pins
RAM reference RAM pin Schematic signal name FPGA pin (IC29) FPGA I/O standard Comments
Address bus (IC35 and IC36 shared signals)
A0 N3 DDR3_BOT_A0 AJ12 SSTL-15 Class I Active termination
A1 P7 DDR3_BOT_A1 AK12 SSTL-15 Class I Active termination
A2 P3 DDR3_BOT_A2 AH11 SSTL-15 Class I Active termination
A3 N2 DDR3_BOT_A3 AH12 SSTL-15 Class I Active termination
A4 P8 DDR3_BOT_A4 AG13 SSTL-15 Class I Active termination
A5 P2 DDR3_BOT_A5 AG14 SSTL-15 Class I Active termination
A6 R8 DDR3_BOT_A6 AK10 SSTL-15 Class I Active termination
A7 R2 DDR3_BOT_A7 AK11 SSTL-15 Class I Active termination
A8 T8 DDR3_BOT_A8 AF11 SSTL-15 Class I Active termination
A9 R3 DDR3_BOT_A9 AG11 SSTL-15 Class I Active termination
A10/AP L7 DDR3_BOT_A10 AJ8 SSTL-15 Class I Active termination
A11 R7 DDR3_BOT_A11 AK8 SSTL-15 Class I Active termination
A12/BC# N7 DDR3_BOT_A12 AJ7 SSTL-15 Class I Active termination
A13 T3 DDR3_BOT_A13 AK7 SSTL-15 Class I Active termination
Bank address bus (IC35 and IC36 shared signals)
BA0 M2 DDR3_BOT_BA0 AH9 SSTL-15 Class I Active termination
BA1 N8 DDR3_BOT_BA1 AH10 SSTL-15 Class I Active termination
BA2 M3 DDR3_BOT_BA2 AJ10 SSTL-15 Class I Active termination
Data bus [0:15] (IC35)
DQ0 E3 DDR3_BOT_DQ0 AF15 SSTL-15 Class I
DQ1 F7 DDR3_BOT_DQ1 AE16 SSTL-15 Class I
DQ2 F2 DDR3_BOT_DQ2 AJ14 SSTL-15 Class I
DQ3 F8 DDR3_BOT_DQ3 AH15 SSTL-15 Class I
DQ4 H3 DDR3_BOT_DQ4 AE17 SSTL-15 Class I
DQ5 H8 DDR3_BOT_DQ5 AD17 SSTL-15 Class I
DQ6 G2 DDR3_BOT_DQ6 AJ15 SSTL-15 Class I
DQ7 H7 DDR3_BOT_DQ7 AF14 SSTL-15 Class I
DQ8 D7 DDR3_BOT_DQ8 AK17 SSTL-15 Class I
DQ9 C3 DDR3_BOT_DQ9 AK16 SSTL-15 Class I
DQ10 C8 DDR3_BOT_DQ10 AG17 SSTL-15 Class I
DQ11 C2 DDR3_BOT_DQ11 AJ18 SSTL-15 Class I
DQ12 A7 DDR3_BOT_DQ12 AG16 SSTL-15 Class I
DQ13 A2 DDR3_BOT_DQ13 AF16 SSTL-15 Class I
DQ14 B8 DDR3_BOT_DQ14 AJ19 SSTL-15 Class I
DQ15 A3 DDR3_BOT_DQ15 AH20 SSTL-15 Class I
Data bus [16:31] (IC36)
DQ0 E3 DDR3_BOT_DQ16 AE18 SSTL-15 Class I
DQ1 F7 DDR3_BOT_DQ17 AD18 SSTL-15 Class I
DQ2 F2 DDR3_BOT_DQ18 AJ20 SSTL-15 Class I
DQ3 F8 DDR3_BOT_DQ19 AK22 SSTL-15 Class I
DQ4 H3 DDR3_BOT_DQ20 AF19 SSTL-15 Class I
DQ5 H8 DDR3_BOT_DQ21 AF18 SSTL-15 Class I
DQ6 G2 DDR3_BOT_DQ22 AH21 SSTL-15 Class I
DQ7 H7 DDR3_BOT_DQ23 AK23 SSTL-15 Class I
DQ8 D7 DDR3_BOT_DQ24 AG19 SSTL-15 Class I
DQ9 C3 DDR3_BOT_DQ25 AG18 SSTL-15 Class I
DQ10 C8 DDR3_BOT_DQ26 AH24 SSTL-15 Class I
DQ11 C2 DDR3_BOT_DQ27 AK25 SSTL-15 Class I
DQ12 A7 DDR3_BOT_DQ28 AE20 SSTL-15 Class I
DQ13 A2 DDR3_BOT_DQ29 AD19 SSTL-15 Class I
DQ14 B8 DDR3_BOT_DQ30 AG24 SSTL-15 Class I
DQ15 A3 DDR3_BOT_DQ31 AK26 SSTL-15 Class I
Data mask[0:1] (IC35)
LDM E7 DDR3_BOT_DM0 AE15 SSTL-15 Class I
UDM D3 DDR3_BOT_DM1 AH19 SSTL-15 Class I
Data mask[2:3] (IC36)
LDM E7 DDR3_BOT_DM2 AJ23 SSTL-15 Class I
UDM D3 DDR3_BOT_DM3 AJ27 SSTL-15 Class I
Data strobe[0:1] (IC35)
LDQS G3 DDR3_BOT_DQS0_P Y16 Differential 1.5-V SSTL Class I
LDQS# F3 DDR3_BOT_DQS0_N AA16 Differential 1.5-V SSTL Class I
UDQS C7 DDR3_BOT_DQS1_P Y17 Differential 1.5-V SSTL Class I
UDQS# B7 DDR3_BOT_DQS1_N Y18 Differential 1.5-V SSTL Class I
Data strobe[2:3] (IC36)
LDQS G3 DDR3_BOT_DQS2_P Y20 Differential 1.5-V SSTL Class I
LDQS# F3 DDR3_BOT_DQS2_N AA20 Differential 1.5-V SSTL Class I
UDQS C7 DDR3_BOT_DQS3_P AB19 Differential 1.5-V SSTL Class I
UDQS# B7 DDR3_BOT_DQS3_N AC19 Differential 1.5-V SSTL Class I
Memory clock (IC35 and IC36 shared signals)
CK# K7 DDR3_BOT_CK_N AA14 Differential 1.5-V SSTL Class I
CK J7 DDR3_BOT_CK_P Y13 Differential 1.5-V SSTL Class I
Control signals(IC35 and IC36 shared signals)
sCKE K9 DDR3_BOT_CKE AK18 SSTL-15 Class I
WE# L3 DDR3_BOT_WEn AK5 SSTL-15 Class I Active termination
CAS# K3 DDR3_BOT_CASn AF9 SSTL-15 Class I Active termination
RAS# J3 DDR3_BOT_RASn AG9 SSTL-15 Class I Active termination
CS# L2 DDR3_BOT_CSn Y12 SSTL-15 Class I Active termination
ODT K1 DDR3_BOT_ODT AH14 SSTL-15 Class I Active termination
RESET# T2 DDR3_BOT_RESETn AK21 1.5V Active termination
VREF (IC35 and IC36 shared signals)
VREFDQ H1 VREF_DDR3_BOT -
VREFCA M8 VREF_DDR3_BOT -
Memory ZQ impedance calibration (IC35)
ZQ L8 DDR3_BOT_RZQ0 -
Memory ZQ impedance calibration (IC36)
ZQ L8 DDR3_BOT_RZQ1 -
FPGA OCT calibration pin
- - OCT_RZQIN0 AK13 SSTL-15
2.2.2.3 USB 3.0 Controller

Software can control LimeSDR-QPCIe board via the USB3 microcontroller (CYUSB3013 (FX3) [link]). The data transfer to/from the board, SPI communication, FPGA configuration is done via the USB3 controller. The controller signals description showed below:

  • FX3_DQ[15:0] - FX3 16-bit GPIF data interface is connected FPGA.
  • FX3_CTL[12:0] - FX3 GPIF interface control signals.
  • FX3_PCLK - GPIF interface clock, connected to FPGA.
  • FX3_SPI - interface is used to program FX3 firmware flash or FPGA configuration flash memory.
  • FX3 I2C - bus is connected to the main I2C bus.
  • PMODE[2:0] – boot options, by default boot from SPI and USB boot is enabled. If J28 jumper is present or R313 is soldered FX3 will boot from IC43 flash memory if correct firmware exists.
  • SW1 – resets FX3
  • J29 – FX3 JTAG programming/debugging pin header.


In the Table 8 are listed USB3.0 controller (FX3) pins, schematic signal name, FPGA interconnections and I/O standard.

Table 8. USB3 controller (FX3) pins
Chip pin (IC42) Chip pin (IC42) Schematic signal name FPGA pin FPGA I/O standard Comments
F10 GPIO0 FX3_DQ0 U12 1.8V
F9 GPIO1 FX3_DQ1 U11 1.8V
F7 GPIO2 FX3_DQ2 U8 1.8V
G10 GPIO3 FX3_DQ3 U9 1.8V
G9 GPIO4 FX3_DQ4 T11 1.8V
F8 GPIO5 FX3_DQ5 R10 1.8V
H10 GPIO6 FX3_DQ6 T10 1.8V
H9 GPIO7 FX3_DQ7 T9 1.8V
J10 GPIO8 FX3_DQ8 V11 1.8V
J9 GPIO9 FX3_DQ9 V9 1.8V
K11 GPIO10 FX3_DQ10 V10 1.8V
L10 GPIO11 FX3_DQ11 W10 1.8V
K10 GPIO12 FX3_DQ12 Y10 1.8V
K9 GPIO13 FX3_DQ13 Y11 1.8V
J8 GPIO14 FX3_DQ14 AA11 1.8V
G8 GPIO15 FX3_DQ15 AA8 1.8V
J6 GPIO16 FX3_PCLK AB16 1.5V
K8 GPIO17 FX3_CTL0 AA9 1.8V
K7 GPIO18 FX3_CTL1 AB8 1.8V
J7 GPIO19 FX3_CTL2 AC9 1.8V
H7 GPIO20 FX3_CTL3 AD9 1.8V
G7 GPIO21 FX3_CTL4 AF8 1.8V
G6 GPIO22 FX3_CTL5 AF7 1.8V
K6 GPIO23 FX3_CTL6 AG7 1.8V
H8 GPIO24 FX3_CTL7 AF6 1.8V
G5 GPIO25 FX3_CTL8 AG6 1.8V
H6 GPIO26 FX3_CTL9 AH7 1.8V
K5 GPIO27 FX3_CTL10 AH6 1.8V
J5 GPIO28 FX3_CTL11 AH4 1.8V
H5 GPIO29 FX3_CTL12 AH5 1.8V
G4 GPIO30 FX3_PMODE0 - 1.8V
H4 GPIO31 FX3_PMODE1 - 1.8V
L4 GPIO32 FX3_PMODE2 - 1.8V
K2 GPIO33 - - -
J4 GPIO34 - - -
K1 GPIO35 - - -
J2 GPIO36 - - -
J3 GPIO37 - - -
J1 GPIO38 - - -
H2 GPIO39 - - -
H3 GPIO40 - - -
F4 GPIO41 FPGA_CONF_DONE L8 - Connected to FPGA configuration status CONF_DONE. Additionally, connected to LED1.
G2 GPIO42 FPGA_NSTATUS K7 - Connected to FPGA nSTATUS pin.
G3 GPIO43 FPGA_NCONFIG C5 - A high-to-low logic initiates a FPGA reconfiguration.
F3 GPIO44 FX3_AS_SW - - Logic level L connects FX3_SPI interface to FPGA conf. Flash (IC30, IC32)
F2 GPIO45 FX3_SPI_AS_SS - - FPGA conf. Flash slave select
F5 GPIO46 FX3_SPI_FPGA_SS - -
E1 GPIO47 FX3_FPGA_GPIO0 AA10 1.8V
E5 GPIO48 FX3_FPGA_GPIO1 AB9 1.8V
E4 GPIO49 FX3_FPGA_GPIO2 AG8 1.8V
D1 GPIO50 FX3_FPGA_GPIO3 AK3 1.5V
D2 GPIO51 FX3_FPGA_GPIO4 AJ4 1.5V
D3 GPIO52 FX3_FPGA_GPIO5 AJ3 1.5V
D4 GPIO53 FX3_SPI_SCLK P20 2.5V/3.3V
C1 GPIO54 FX3_SPI_FLASH_SS - - Connected to FX3 memory through header J28
C2 GPIO55 FX3_SPI_MISO M21 2.5V/3.3V
D5 GPIO56 FX3_SPI_MOSI N20 2.5V/3.3V
C4 GPIO57 - - -
A3 SSRXM FX3_USB_SSRX_P - -
A4 SSRXP FX3_USB_SSRX_N - -
A6 SSTXM FX3_USB_SSTX_IC_P - -
A5 SSTXP FX3_USB_SSTX_IC_N - -
B3 R_usb3 - - - USB3 precision resistor
C9 OTG_ID FX3_USB_OTG_ID - -
A9 DP FX3_USB_D_P - -
A10 DM FX3_USB_D_N - -
C8 R_usb2 - - - USB2 precision resistor
E11 VBUS FX3_VBUS - -
B2 FSLC[0] - - - 10k pulldown for 19.2MHz crystal selection
C6 XTALIN CYUSB_XTAL_P - -
C7 XTALOUT CYUSB_XTAL_N - -
B4 FSLC[1] - - - 10k pulldown for 19.2MHz crystal selection
E6 FSLC[2] - - -
D7 CLKIN - - -
D6 CLKIN_32 - - -
D9 I2C_SCL FX3_I2C_SCL/ I2C_SCL AG23 1.5V Voltage level reduced to connect to FPGA. Net labels on FPGA side: I2C_SCL_LS, I2C_SDA_LS
D10 I2C_SDA FX3_I2C_SDA/ I2C_SDA AH22 1.5V
E7 TDI FX3_JTAG_TDI - - 10-pin JTAG connector J29
C10 TDO FX3_JTAG_TDO - -
B11 TRST# FX3_JTAG_TRST - -
E8 TMS FX3_JTAG_TMS - -
F6 TCK FX3_JTAG_TCK - -
D11 O[60] - - -
2.2.2.4 ADC

There is one Dual-Channel 14-Bit, analog-to-digital converter (ADS4246 – IC37) mounted on board. ADC analog input is connected to RX BB outputs of LMS7002M#1 IC. Digital output pins are connected to FPGA.

The Table 9 lists 14-bit analog to digital converter ADC (IC37) pins, schematic signal name, FPGA interconnections and I/O standard.

Table 9 14-bit ADC (IC37) digital interface pins
Chip pin (IC37) Chip reference (IC37) Schematic signal name FPGA pin FPGA I/O standard
41 DA0_P/DA1 ADC_DA0_P L10 1.5V
40 DA0_M/DA0 ADC_DA0_N L9 1.5V
43 DA2_P/DA3 ADC_DA1_P P10 1.5V
42 DA2_M/DA2 ADC_DA1_N N11 1.5V
45 DA4_P/DA5 ADC_DA2_P N10 1.5V
44 DA4_M/DA4 ADC_DA2_N N9 1.5V
47 DA6_P/DA7 ADC_DA3_P R12 1.5V
46 DA6_M/DA6 ADC_DA3_N R11 1.5V
51 DA8_P/DA13 ADC_DA4_P P12 1.5V
50 DA8_M/DA12 ADC_DA4_N N12 1.5V
53 DA10_P/DA9 ADC_DA5_P M12 1.5V
52 DA10_M/DA8 ADC_DA5_N M11 1.5V
55 DA12_P/DA11 ADC_DA6_P L11 1.5V
54 DA12_M/DA10 ADC_DA6_N K11 1.5V
61 DB0_P/DB1 ADC_DB0_P K12 1.5V
60 DB0_M/DB0 ADC_DB0_N J12 1.5V
63 DB2_P/DB3 ADC_DB1_P E22 1.5V
62 DB2_M/DB2 ADC_DB1_N E21 1.5V
3 DB4_P/DB5 ADC_DB2_P E10 1.5V
2 DB4_M/DB4 ADC_DB2_N D10 1.5V
5 DB6_P/DB7 ADC_DB3_P G14 1.5V
4 DB6_M/DB6 ADC_DB3_N F14 1.5V
7 DB8_P/DB13 ADC_DB4_P H12 1.5V
6 DB8_M/DB12 ADC_DB4_N G12 1.5V
9 DB10_P/DB9 ADC_DB5_P J14 1.5V
8 DB10_M/DB8 ADC_DB5_N H14 1.5V
11 DB12_P/DB11 ADC_DB6_P K13 1.5V
10 DB12_M/DB10 ADC_DB6_N J13 1.5V
35 CTRL1 ADC_CTRL1 - -
36 CTRL2 ADC_CTRL2 - -
34 CTRL3 ADC_CTRL3 - -
29 INP_A ADC_INA_P - -
30 INM_A ADC_INA_N - -
23 VCM ADC_VCM - -
57 CLKOUTP/CLKOUT ADC_CLKOUT_P L14 1.5V
56 CLKOUTM/UNUSED ADC_CLKOUT_N L13 1.5V
19 INP_B ADC_INB_P - -
20 INM_B ADC_INB_N - -
25 CLKP ADC_CLK_P - -
26 CLKM ADC_CLK_N - -
13 SCLK FPGA_SPI0_SCLK T25 2.5V/3.3V
14 SDATA FPGA_SPI0_MOSI R26 2.5V/3.3V
64 SDOUT FPGA_SPI0_MISO_ADC L20 1.5V
15 SEN FPGA_SPI0_ADC_SS E26 1.5V
12 RESET FPGA_ADC_RESET D6 1.5V
2.2.2.5 DACs

LimeSDR-QPCIe board has two 14-Bit Dual Transmit Digital-To-Analog Converters. By default, analog output pins are connected to TX BB input pads of LMS70002M#1 IC. By changing on-board resistors it can be connected to LMS70002M#2 instead. To connect DACs to LMS70002M#2 TX BB input pads R268, R271, R275, R279, R270, R274, R278, R282 resistors has to be removed and R269, R273, R277, R281, R272, R276, R280, R283 resistors has to be fitted.

The tables below list 14-bit digital to analog converter DAC#1 (IC40 - Table 10) and DAC#2 (IC41 - Table 11) pins, schematic signal name, FPGA interconnections and I/O standard.

Table 10 14-bit DAC#1 (IC40) digital interface pins
Chip pin (IC40) Chip reference (IC40) Schematic signal name FPGA pin FPGA I/O standard Comment
14 DA0 DAC1_DA0 E27 2.5V/3.3V
13 DA1 DAC1_DA1 F25 2.5V/3.3V
12 DA2 DAC1_DA2 D28 2.5V/3.3V
11 DA3 DAC1_DA3 E28 2.5V/3.3V
10 DA4 DAC1_DA4 F30 2.5V/3.3V
9 DA5 DAC1_DA5 E30 2.5V/3.3V
8 DA6 DAC1_DA6 D27 2.5V/3.3V
7 DA7 DAC1_DA7 C29 2.5V/3.3V
6 DA8 DAC1_DA8 C30 2.5V/3.3V
5 DA9 DAC1_DA9 D29 2.5V/3.3V
4 DA10 DAC1_DA10 D30 2.5V/3.3V
3 DA11 DAC1_DA11 B29 2.5V/3.3V
2 DA12 DAC1_DA12 A29 2.5V/3.3V
1 DA13 DAC1_DA13 B28 2.5V/3.3V
17, 18 WRTA/WRTIQ, CLKA/CLKIQ DAC1_CLK - 2.5V/3.3V Clocked from buffer IC55 pin 3. Clock value passed from FPGA to buffer from FPGA pin M23, DAC_CLK_WRT
36 DB0 DAC1_DB0 F28 2.5V/3.3V
35 DB1 DAC1_DB1 F30 2.5V/3.3V
34 DB2 DAC1_DB2 J28 2.5V/3.3V
33 DB3 DAC1_DB3 F29 2.5V/3.3V
32 DB4 DAC1_DB4 K30 2.5V/3.3V
31 DB5 DAC1_DB5 K28 2.5V/3.3V
30 DB6 DAC1_DB6 G29 2.5V/3.3V
29 DB7 DAC1_DB7 J29 2.5V/3.3V
28 DB8 DAC1_DB8 J30 2.5V/3.3V
27 DB9 DAC1_DB9 H27 2.5V/3.3V
26 DB10 DAC1_DB10 H29 2.5V/3.3V
25 DB11 DAC1_DB11 H30 2.5V/3.3V
24 DB12 DAC1_DB12 H26 2.5V/3.3V
23 DB13 DAC1_DB13 H25 2.5V/3.3V
19, 20 WRTB/RESETIQ, CLKB/SELECTIQ DAC1_CLK - 2.5V/3.3V Clocked from buffer IC55 pin 3. Clock value passed from FPGA to buffer from FPGA pin M23, DAC_CLK_WRT
48 MODE DAC1_MODE J23 2.5V/3.3V
37 SLEEP DAC1_SLEEP J25 2.5V/3.3V
42 GSET - - 3.3V Hardwired to VCC3P3D_DAC1
43 EXTIO - - - Connected to 100nF capacitor


Table 11 14-bit DAC#2 (IC41) digital interface pins
Chip pin (IC41) Chip reference (IC41) Schematic signal name FPGA pin FPGA I/O standard Comment
14 DA0 DAC2_DA0 R27 2.5V/3.3V
13 DA1 DAC2_DA1 K26 2.5V/3.3V
12 DA2 DAC2_DA2 N27 2.5V/3.3V
11 DA3 DAC2_DA3 P30 2.5V/3.3V
10 DA4 DAC2_DA4 N29 2.5V/3.3V
9 DA5 DAC2_DA5 M27 2.5V/3.3V
8 DA6 DAC2_DA6 M28 2.5V/3.3V
7 DA7 DAC2_DA7 L26 2.5V/3.3V
6 DA8 DAC2_DA8 L28 2.5V/3.3V
5 DA9 DAC2_DA9 L29 2.5V/3.3V
4 DA10 DAC2_DA10 L25 2.5V/3.3V
3 DA11 DAC2_DA11 L30 2.5V/3.3V
2 DA12 DAC2_DA12 P29 2.5V/3.3V
1 DA13 DAC2_DA13 N26 2.5V/3.3V
17, 18 WRTA/WRTIQ, CLKA/CLKIQ DAC2_CLK - 2.5V/3.3V Clocked from buffer IC55 pin 5. Clock value passed from FPGA to buffer from FPGA pin M23, DAC_CLK_WRT
36 DB0 DAC2_DB0 P26 2.5V/3.3V
35 DB1 DAC2_DB1 N25 2.5V/3.3V
34 DB2 DAC2_DB2 P25 2.5V/3.3V
33 DB3 DAC2_DB3 R28 2.5V/3.3V
32 DB4 DAC2_DB4 R25 2.5V/3.3V
31 DB5 DAC2_DB5 K27 2.5V/3.3V
30 DB6 DAC2_DB6 N24 2.5V/3.3V
29 DB7 DAC2_DB7 M23 2.5V/3.3V
28 DB8 DAC2_DB8 M22 2.5V/3.3V
27 DB9 DAC2_DB9 N22 2.5V/3.3V
26 DB10 DAC2_DB10 R20 2.5V/3.3V
25 DB11 DAC2_DB11 T21 2.5V/3.3V
24 DB12 DAC2_DB12 R21 2.5V/3.3V
23 DB13 DAC2_DB13 R22 2.5V/3.3V
19, 20 WRTB/RESETIQ, CLKB/SELECTIQ DAC2_CLK - 2.5V/3.3V Clocked from buffer IC55 pin 5. Clock value passed from FPGA to buffer from FPGA pin M23, DAC_CLK_WRT
48 MODE DAC2_MODE L23 2.5V/3.3V
37 SLEEP DAC2_SLEEP L24 2.5V/3.3V
42 GSET - - 3.3V Hardwired to VCC3P3D_DAC2
43 EXTIO - - - Connected to 100nF capacitor
2.2.2.6 GNSS receiver

LimeSDR-QPCIe board has GNSS receiver module GPS/GNSS M0578 (IC48). External active antenna for this module can be connected to J34 connector. Module is connected to FPGA (IC29), pin connections can be found on Table 12.

Table 12 GNSS receiver pin connections
GNSS pin (IC48) GNSS module reference (IC48) Schematic signal name FPGA pin FPGA I/O standard
9 UART RX GNSS_RX K25 3.3V(2.5V)
10 UART TX GNSS_TX K22 3.3V(2.5V)
6 1PPS GNSS_TPULSE T23 3.3V(2.5V)
13 FIX GNSS_FIX R23 3.3V(2.5V)
2.2.2.7 RTC

For applications which requires accurate time LimeSDR-QPCIe has mounted Real-Time-Clock DS3231 (IC50). Pin connections can be found in Table 13. For I2C interface see chapter 2.2.4.2 I2C interfaces.

Table 13 RTC pin connections
RTC pin (IC50) RTC chip reference (IC50) Schematic signal name FPGA pin FPGA I/O standard Comment
16 SCL I2C_SCL AG23 1.5V Connected through level convertor to I2C_SCL_LS.
15 SDA I2C_SDA AH22 1.5V Connected through level convertor to I2C_SDA_LS.
3 INT/SQW RTC_INT_SQW K15 1.5V 10k, Pull-UP, resistor.
1 32kHz RTC_32KHZ H17 1.5V 10k, Pull-UP, resistor.
2.2.2.8 Temperature sensor

Board temperature can be measured with LM75 (IC47) temperature sensor using its I2C interface. Pin connections can be found in Table 13. For I2C interface of this sensor see chapter 2.2.4.2 I2C interfaces.

Table 14 Temperature sensor pin connections
LM75 pin (IC47) LM75 pin (IC47) Schematic signal name FPGA pin FPGA I/O standard Comment
16 SCL I2C_SCL AG23 1.5V Connected through level convertor to I2C_SCL_LS.
15 SDA I2C_SDA AH22 1.5V Connected through level convertor to I2C_SDA_LS.
3 INT/SQW RTC_INT_SQW K15 1.5V 10k, Pull-up, resistor.
1 32kHz RTC_32KHZ H17 1.5V 10k, Pull-up, resistor.

2.2.3 Connectors

This chapter describes connectors that exists on LimeSDR-QPCIe v1.2 board.

2.2.3.1 PCI Express connector

For data transfer LimeSDR – QPCIe board has PCI express connector with four lanes. PCI express interface is implemented in FPGA. Pin connection and corresponding signal names are listed in Table 15.

Table 15 PCIe connector pins
PCIe connector pin Schematic signal name FPGA pin I/O standard Comment
B5 PCIE_SMCLK W12 1.5V Connected through voltage level shifter to 1.5V
B6 PCIE_SMDAT V12 1.5V Connected through voltage level shifter to 1.5V
B11 PCIE_WAKEn G26 3.3V Signal is disconnected with not fitted R100 resistor
B14 PCIE_HSO0_P AG2 1.5-V PCML
B15 PCIE_HSO0_N AG1 1.5-V PCML
B19 PCIE_HSO1_P AE2 1.5-V PCML
B20 PCIE_HSO1_N AE1 1.5-V PCML
B23 PCIE_HSO2_P AC2 1.5-V PCML
B24 PCIE_HSO2_N AC1 1.5-V PCML
B27 PCIE_HSO3_P AA2 1.5-V PCML
B28 PCIE_HSO3_N AA1 1.5-V PCML
A11 PCIE_PERSTn W24 3.3V
A13 PCIE_REFCLK_P W8 HCSL
A14 PCIE_REFCLK_N W7 HCSL
A16 PCIE_HSI0_P AF4 1.5-V PCML AC coupled
A17 PCIE_HSI0_N AF3 1.5-V PCML AC coupled
A21 PCIE_HSI1_P AD4 1.5-V PCML AC coupled
A22 PCIE_HSI1_N AD3 1.5-V PCML AC coupled
A25 PCIE_HSI2_P AB4 1.5-V PCML AC coupled
A26 PCIE_HSI2_N AB3 1.5-V PCML AC coupled
A29 PCIE_HSI3_P Y4 1.5-V PCML AC coupled
A30 PCIE_HSI3_N Y3 1.5-V PCML AC coupled
2.2.3.2 LVDS connector

J30 is dedicated connector for FPGA transceiver (LVDS) applications.

Table 16 LVDS connector pins
LVDS connector pin Schematic signal name FPGA pin I/O standard Comment
1 GND -
3 EXT_GXB_RX6_P R2 Depends from design
5 EXT_GXB_RX6_N R1
7 GND -
9 EXT_GXB_TX6_P P4 Depends from design AC Coupled
11 EXT_GXB_TX6_N P3 AC Coupled
13 GND -
15 EXT_GXB_CLK_P P8 Depends from design
17 EXT_GXB_CLK_N N7
19 GND -
2 GND -
4 EXT_GXB_RX7_P N2 Depends from design
6 EXT_GXB_RX7_N N1
8 GND -
10 EXT_GXB_TX7_P M4 Depends from design AC Coupled
12 EXT_GXB_TX7_N M3 AC Coupled
14 GND -
16 VCC5P0(VCC3P3) -
18 VCC5P0(VCC3P3) -
20 GND -
2.2.3.3 PMOD connectors

Two 10 pin 0.1” right angle PMOD connectors (J31, J32) are connected to the FPGA. A complete pinout description, dedicated FPGA pins and their I/O standard is presented in the tables below.

Table 17. FPGA PMOD#A (J32) connector pins
PMOD#A connector pin Schematic signal name FPGA pin FPGA cI/O standard Comment
1 PMOD_A_PIN1_LS AD12 1.5V Level shifter (1.5V to 3.3V) between FPGA and connector
2 PMOD_A_PIN2_LS AE10 1.5V
3 PMOD_A_PIN3_LS AF10 1.5V
4 PMOD_A_PIN4_LS AD13 1.5V
7 PMOD_A_PIN7_LS AE12 1.5V
8 PMOD_A_PIN8_LS AE13 1.5V
9 PMOD_A_PIN9_LS AJ2 1.5V
10 PMOD_A_PIN10_LS AJ1 1.5V
5, 11 VCC3P3 - - 3.3V power
6, 12 GND - - Ground
Table 18. FPGA PMOD#B (J31) connector pins
PMOD#B connector pin Schematic signal name FPGA pin FPGA cI/O standard Comment
1 PMOD_B_PIN1_LS AF20 1.5V Level shifter (1.5V to 3.3V) between FPGA and connector
2 PMOD_B_PIN2_LS AG21 1.5V
3 PMOD_B_PIN3_LS AF21 1.5V
4 PMOD_B_PIN4_LS AD20 1.5V
7 PMOD_B_PIN7_LS AK27 1.5V
8 PMOD_B_PIN8_LS AE22 1.5V
9 PMOD_B_PIN9_LS AC21 1.5V
10 PMOD_B_PIN10_LS AH26 1.5V
5, 11 VCC3P3 - - 3.3V power
6, 12 GND - - Ground

2.2.4 Low Speed Interfaces

This chapter describes low speed interfaces on LimeSDR-QPCIe v1.2 board which are dedicated to communicate between various board components.

LimeSDR-QPCIe board low speed interface is divided into FPGA-RF and FPGA-FX3 groups and are presented in Figure 6 and Figure 7. The latter block diagrams depict the main ICs, corresponding IC pin numbers, data buses and serial protocol addresses.


Figure 6 FPGA-RF circuit low speed interface block diagram


LimeSDR-QPCIe board peripherals can be controlled via USB interface. All commands that comes from USB are firstly processed by FX3 controller. I2C and multiple SPI interfaces provide connection to various on-board ICs, such as temperature sensor, port expander, clock generator, memory and real-time clock (RTC).


Figure 7 LimeSDR-QPCIe v1.2 FPGA-FX3 low speed interface block diagram
2.2.4.1 SPI interfaces

There are several SPI interfaces with their slave devices:

  • FX3_SPI - Master of this bus is CYUSB3013 (IC42) and this bus has these slave devices:
    • Flash memory M25P40 (IC43) dedicated for FX3 firmware;
    • Flash memory W25Q128 (IC30) or S25FL128 (IC32) dedicated for FPGA configuration file. Using switch (IC31) flash memory is switched from FPGA to FX3_SPI BUS. Then flash content is updated and flash memory is switched back to FPGA. This is done when it is needed to update FPGA gateware in flash memory.
    • FPGA (IC29) - If SPI slave is implemented in FPGA logic it can be accessed through FX3_SPI interface.
Table 19 FX3_SPI interface
FX3 pin (IC42) FX3 chip reference (IC42) FX3 pin (IC42) FPGA pin (IC29) I/O standard
D4 SPI_SCK FX3_SPI_SCLK P20 3.3V
D5 SPI_MOSI FX3_SPI_MOSI N20 3.3V
C2 SPI_MISO FX3_SPI_MISO M21 3.3V
F5 GPIO[46] FX3_SPI_FPGA_SS AG22 3.3V
F2 GPIO[45] FX3_SPI_AS_SS - 3.3V
C1 SPI_SSN FX3_SPI_FLASH_SS - 3.3V
  • FPGA_SPI0 – master of this interface is FPGA (IC29), slave devices of this interface:
    • RFIC LMS7002M (IC1)
    • RFIC LMS7002M (IC2)
    • 14-bit ADC ADS4246 (IC37)
    • XO VC DAC AD5662 (IC54)
    • Phase detector ADF4002 (IC53)
Table 20 FPGA_SPI0 interface
Schematic signal name FPGA pin(IC29) I/O standard Comment
FPGA_SPI0_SCLK T25 2.5V(3.3V)
FPGA_SPI0_MOSI R26 2.5V(3.3V)
FPGA_SPI0_MISO_LMS1 R30 2.5V(3.3V)
FPGA_SPI0_MISO_LMS2 V30 2.5V(3.3V)
FPGA_SPI0_MISO_ADC L20 1.8V
FPGA_SPI0_LMS1_SS V29 2.5V(3.3V)
FPGA_SPI0_LMS2_SS U29 2.5V(3.3V)
FPGA_SPI0_ADC_SS E26 1.5V Configure FPGA output as Open-Drain
FPGA_SPI0_DAC_SS G23 1.5V Configure FPGA output as Open-Drain
FPGA_SPI0_ADF_SS E25 1.5V Configure FPGA output as Open-Drain
  • FPGA_SPI1: master of this interface is FPGA (IC29), slave devices of this interface:
    • Flash memory M25P40 (IC46)
Table 21 FPGA_SPI1 interface
Schematic signal name FPGA pin(IC29) I/O standard Comment
FPGA_SPI1_SCLK_LS AF13 1.5V Connected through voltage level shifter. Net label on memory side FPGA_SPI1_SCLK
FPGA_SPI1_MOSI_LS AG12 1.5V Connected through voltage level shifter. Net label on memory side FPGA_SPI1_MOSI
FPGA_SPI1_MISO_LS AB12 1.5V Connected through voltage level shifter. Net label on memory side FPGA_SPI1_MISO
FPGA_SPI1_FLASH_SS_LS AB13 1.5V Connected through voltage level shifter. Net label on memory side FPGA_SPI1_FLASH_SS
  • FPGA_SPI2: master of this interface is FPGA (IC29), slave devices of this interface:
    • 6x ADC (IC18, IC20, IC23, IC25, IC26, IC28) dedicated for onboard RSSI use.
Table 22 FPGA_SPI2 interface
Schematic signal name FPGA pin(IC29) I/O standard Comment
FPGA_SPI2_SCLK_LS AK15 1.5V Connected through voltage level shifter and clock buffer to all six ADC. Net label after level shifter FPGA_SPI2_SCLK. Fanouts through clock buffer to nets:

FPGA_SPI2_LMS1_RX1_I_SCLK, FPGA_SPI2_LMS1_RX1_Q_SCLK, FPGA_SPI2_LMS2_RX2_I_SCLK, FPGA_SPI2_LMS2_RX1_Q_SCLK, FPGA_SPI2_LMS2_RX1_I_SCLK, FPGA_SPI2_LMS2_RX2_Q_SCLK

FPGA_SPI2_LMS1_RX1_I_MISO J7 1.5V
FPGA_SPI2_LMS1_RX1_Q_MISO A3 1.5V
FPGA_SPI2_LMS2_RX1_I_MISO H15 1.5V
FPGA_SPI2_LMS2_RX1_Q_MISO G9 1.5V
FPGA_SPI2_LMS2_RX2_I_MISO C27 1.5V
FPGA_SPI2_LMS2_RX2_Q_MISO F6 1.5V
FPGA_SPI2_LMS_RX_DET_SS AJ17 1.5V
2.2.4.2 I2C interfaces

Board has three independent I2C interfaces: I2C, LMS1_I2C and LMS2_I2C. I2C – master of this interface can be either FX3 (IC42) or either FPGA (IC29). Master selection is done through R287 and R288 resistors. By default, master is FX3 (resistors fitted). To select FPGA as master, remove R287 and R288 resistors. This interface has several slave devices which are listed in Table 23.

  • RTC DS3231 (IC50);
  • EEPROM M24128 (IC51);
  • Temperature sensor LM75 (IC47), EEPROM and clock generator. Information for slave devices are provided in Table 23, signal connectivity information is in Table 24.
Table 23 I2C interface devices
I2C slave device Slave device I2C address I/O standard Comment
IC47 Temperature sensor 1 0 0 1 0 0 0 RW 3.3V LM75
IC51 EEPROM 1 0 1 0 0 0 0 RW 3.3V M24128
IC57 Clock generator 1 1 0 0 0 0 0 RW 3.3V Si5351C
IC50 Real-time clock (RTC) 1 1 0 1 0 0 0 RW 3.3V DS3231
Table 24 I2C interface pins
Schematic signal name FPGA pin (IC29) FX3 pin (IC42) I/O standard Comment
I2C_SDA_LS AH22 - 1.5V Connected through level converter to I2C_SDA. Remove R287 and R288 to use FPGA as I2C master.
I2C_SCL_LS AG23 - 1.5V Connected through level converter to I2C_SCL. Remove R287 and R288 to use FPGA as I2C master.
FX3_I2C_SDA - D9 3.3V Connected through R287 to I2C_SDA.
FX3_I2C_SCL - D10 3.3V Connected through R288 to I2C_SCL.
  • LMS1_I2C: this interface has two EEPROMs. This interface is only accessible from LMS7002M (IC1). In Table 25 are listed all LMS1_I2C slave devices and their information. In Table 26 listed pin connections.
Table 25 LMS1_I2C interface devices
I2C slave device Slave device I2C address I/O standard Comment
IC3 EEPROM for LMS7 MCU firmware 1 0 1 0 A2 A1 A0 RW 2.5V(3.3V) M24128
IC4 EEPROM 1 0 1 0 A2 A1 A0 RW 2.5V(3.3V) 24FC512
Table 26 LMS1_I2C pins
Schematic signal name RFIC pin (IC1) I/O standard Comment
LMS1_I2C_SDA D26 2.5V(3.3V) Accessible only from IC1
LMS1_I2C_SCL C27 2.5V(3.3V) Accessible only from IC1
  • LMS2_I2C: this interface has two EEPROMs. This interface is only accessible from LMS7002M (IC2). In Table 27 are listed all LMS1_I2C slave devices and their information. In Table 28 listed pin connections.
Table 27 LMS2_I2C interface devices
I2C slave device Slave device I2C address I/O standard Comment
IC5 EEPROM for LMS7 MCU firmware 1 0 1 0 A2 A1 A0 RW 2.5V(3.3V) M24128
IC6 EEPROM 1 0 1 0 A2 A1 A0 RW 2.5V(3.3V) 24FC512
Table 28 LMS2_I2C pins
Schematic signal name RFIC pin (IC2) I/O standard Comment
LMS2_I2C_SDA D26 2.5V(3.3V) Accessible only from IC2
LMS2_I2C_SCL C27 2.5V(3.3V) Accessible only from IC2
2.2.4.3 UART

UART interface is dedicated for communication between FPGA and GNSS receiver GPS/GNSS M0578 (IC48).

Table 29 GNSS UART interface pins
Schematic signal name FPGA pin (IC29) I/O standard
GNSS_RX K25 3.3V(2.5V)
GNSS_TX K22 3.3V(2.5V)

2.2.5 User I/O

This chapter describes available inputs and outputs of LimeSDR-QPCIe v1.2 board which can be used for user applications.

2.2.5.1 FPGA switch

4 poles slide switch SW2 is connected to FPGA and can be used to implement additional functionality which requires input control. Each switch line has external pull up resistors. When switch is in position “On”, it pulls down the line to logic ‘0’ level.

Figure 8 LimeSDR-QPCIe v1.2 4 poles slide switch


In Table 30 are listed each switch line and correspond FPGA pins.

Table 30 FPGA Switch connections
Switch pole Schematic signal name FPGA pin(IC29) I/O standard
1 FPGA_SW0 H7 1.5V
2 FPGA_SW1 A2 1.5V
3 FPGA_SW2 E6 1.5V
4 FPGA_SW3 F8 1.5V
2.2.5.2 Indication LEDs

LimeSDR-QPCIe board comes with four single colour (green) general purpose LEDs, one general purpose dual colour (red-green) LED, one green LED informing about successful FPGA configuration and one for power indication.

Figure 9LimeSDR-QPCIe v1.2 indication LEDs


All LEDs are connected to FPGA and their function can be changed except for LED1. Default LEDs functions and other information are listed in the table below.

Table 31 Default functions of LEDs
Board Reference Schematic name Board label Type Description
LED1 FPGA_CONF_DONE FPGA CONF FPGA status LED lights up after successful FPGA configuration
LED2, LED3, LED4, LED5 FPGA_LED1, FPGA_LED2, FPGA_LED3, FPGA_LED4 FPGA LED1, FPGA LED2, FPGA LED3, FPGA LED4 General purpose General purpose reconfigurable single colour LED.
LED6 FPGA_LED5_G, FPGA_LED5_R FPGA LED5 General purpose General purpose reconfigurable dual colour (red-green) LED.
LED7 VCC3P3, GND BOARD POWER Power indication LED lights up when VCC3P3 power rail is active.

2.2.6 RF Loopback Control

There is RF loopback circuit for RF transceivers which can be controlled from FPGA through shift registers 74HC595 (IC7 and IC8). Pin connection can be found in Table 32.

Table 32 Pin connection of shift registers
Schematic signal name FPGA pin(IC29) I/O standard Comment
SR_SCLK_LS AA13 1.5V Connected through level converter to SR_SCLK.
SR_DIN_LS AJ5 1.5V Connected through level converter to SR_DIN.
SR_LATCH_LS B26 1.5V Connected through level converter to SR_LATCH.
Table 33 LMS#1 loopback control truth table
IC7 pin reference Result
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
x x x x L H x x LMS#1 TX1_2 → U.FL (J13)
x x x x H L x x LMS#1 TX1_2 → LMS#1 RX1_H
x x H x x x x x LMS#1 TX1_2 shunt to ground on
x x L x x x x x LMS#1 TX1_2 shunt to ground off
x x x H x x x x LMS#1 TX1_2 → RX1_H attenuation -40 dB
x x x L x x x x LMS#1 TX1_2 → RX1_H attenuation -25 dB
x x x x x x L H LMS#1 TX2_2 → U.FL (J17)
x x x x x x H L LMS#1 TX2_2 → LMS#1 RX2_H
H x x x x x x x LMS#1 TX2_2 shunt to ground on
L x x x x x x x LMS#1 TX2_2 shunt to ground off
x H x x x x x x LMS#1 TX2_2 → RX2_H attenuation -40 dB
x L x x x x x x LMS#1 TX2_2 → RX2_H attenuation -25 dB
Note 1:    Schematic signals corresponds to IC7 pins as below:
Q0 – LMS1_TX2_2_LB_SH   Q1 – LMS1_TX2_2_LB_AT   Q2 – LMS1_TX1_2_LB_SH   Q3 – LMS1_TX1_2_LB_AT
Q4 – LMS1_TX1_2_LB_H    Q5 – LMS1_TX1_2_LB_L    Q6 – LMS1_TX2_2_LB_H    Q7 – LMS1_TX2_2_LB_L
Table 34 LMS#2 loopback control truth table
IC8 pin reference Result
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
x x H L x x x x LMS#2 TX1_2 → U.FL (J14)
x x L H x x x x LMS#2 TX1_2 → LMS#2 RX1_H
x x x x x H x x LMS#2 TX1_2 shunt to ground on
x x x x x L x x LMS#2 TX1_2 shunt to ground off
x x x x x x H x LMS#2 TX1_2 → RX1_H attenuation -40 dB
x x x x x x L x LMS#2 TX1_2 → RX1_H attenuation -25 dB
H L x x x x x x LMS#2 TX2_2 → U.FL (J18)
L H x x x x x x LMS#2 TX2_2 → LMS#2 RX2_H
x x x x x x x H LMS#2 TX2_2 shunt to ground on
x x x x x x x L LMS#2 TX2_2 shunt to ground off
x x x x H x x x LMS#2 TX2_2 → RX2_H attenuation -40 dB
x x x x L x x x LMS#2 TX2_2 → RX2_H attenuation -25 dB
Note 1:    
 Q0 – LMS2_TX2_2_LB_L   Q1 – LMS2_TX2_2_LB_H    Q2 – LMS2_TX1_2_LB_L    Q3 – LMS2_TX1_2_LB_H
 Q4 – LMS2_TX2_2_LB_AT  Q5 – LMS2_TX1_2_LB_SH   Q6 – LMS2_TX1_2_LB_AT   Q7 – LMS2_TX2_2_LB_SH

The table below describes RF transceiver LMS7002#1 and LMS7002#2 external loopback configuration, pins, schematic signal name, FPGA interconnections and I/O standard.

Table 35 LMS7002 (IC1, IC2) external loopback configuration
Loopback for RF switch Schematic control signal name Shift register pin FPGA-shift register pins Comment
LMS7002 #1 (IC1) IC10, IC12 LMS1_TX1_2_LB_L LMS1_TX1_2_LB_H IC7.Q5 IC7.Q4 AJ5, AA13, B26 (through level shifter IC9) When LMS1_TX1_2_LB_L is high andLMS1_TX1_2_LB_H is low then LMS#1 TX1_2 (LMS1_LOOPBACK_TX12 net) is fed to U.FL connector J13. When LMS1_TX1_2_LB_L is low and LMS1_TX1_2_LB_H is high then LMS#1 TX1_2 (LMS1_LOOPBACK_TX12 net) is fed to LMS#1 RX1_H (LMS1_LOOPBACK_RX1H net)
IC14, IC15 LMS1_TX2_2_LB_L LMS1_TX2_2_LB_H IC7.Q7 IC7.Q6 When LMS1_TX2_2_LB_L is high and LMS1_TX2_2_LB_H is low then LMS#1 TX2_2 (LMS1_LOOPBACK_TX22 net) is fed to U.FL connector J17. When LMS1_TX2_2_LB_L is low and LMS1_TX2_2_LB_H is high then LMS#1 TX2_2 (LMS1_LOOPBACK_TX22 net) is fed to LMS#1 RX2_H (LMS1_LOOPBACK_RX2H net)
VT3, VT9 LMS1_TX1_2_LB_SH IC7.Q2 Loopback shunt to ground for high isolation. When high – shunt active, when low – shunt off.
VT1 LMS1_TX1_2_LB_AT IC7.Q0 When LMS1_TX1_2_LB_AT is low, TX1_2 to RX1_H loopback attenuation is set to -40 dB. When LMS1_TX1_2_LB_AT is high, loopback attenuation is set to -25 dB.
VT7 LMS1_TX2_2_LB_AT IC7.Q1 When LMS1_TX2_2_LB_AT is low, TX2_2 to RX2_H loopback attenuation is set to -40 dB. When LMS1_TX2_2_LB_AT is high, loopback attenuation is set to -25 dB.
LMS7002#2 (IC2) IC11, IC13 LMS2_TX1_2_LB_L LMS2_TX1_2_LB_H IC8.Q2 IC8.Q3 When LMS2_TX1_2_LB_L is high and LMS2_TX2_2_LB_H is low then LMS#2 TX1_2 (LMS2_LOOPBACK_TX12 net) is fed to U.FL connector J14. When LMS2_TX1_2_LB_L is low and LMS2_TX1_2_LB_H is high then LMS#2 TX1_2 (LMS2_LOOPBACK_TX12 net) is fed to LMS#2 RX1_H (LMS2_LOOPBACK_RX1H net)
IC15, IC17 LMS2_TX2_2_LB_L LMS2_TX2_2_LB_H IC8.Q0 IC8.Q1 When LMS2_TX2_2_LB_L is high and LMS2_TX2_2_LB_H is low then LMS#2 TX2_2 (LMS2_LOOPBACK_TX22 net) is fed to U.FL connector J18. When LMS2_TX2_2_LB_L is low and LMS2_TX2_2_LB_H is high then LMS#2 TX2_2 (LMS2_LOOPBACK_TX22 net) is fed to LMS#2 RX2_H (LMS2_LOOPBACK_RX2H net)
VT11, VT12 LMS2_TX2_2_LB_SH IC8.Q7 Loopback shunt to ground for high isolation. When high – shunt active, when low – shunt off.
VT2 LMS2_TX1_2_LB_AT IC8.Q6 When LMS2_TX1_2_LB_AT is low, TX1_2 to RX1_H loopback attenuation is set to -40 dB. When LMS2_TX1_2_LB_AT is high, loopback attenuation is set to -25 dB.
VT8 LMS2_TX2_2_LB_AT IC8.Q4 When LMS2_TX2_2_LB_AT is low, TX2_2 to RX2_H loopback attenuation is set to -40 dB. When LMS2_TX2_2_LB_AT is high, loopback attenuation is set to -25 dB.

2.2.7 Board Temperature Control

LimeSDR-QPCIe has integrated temperature sensor (IC47) which controls FAN to keep board in operating temperature range. FAN has dedicated holes for mounting over the main digital ICs (FPGA, DDRs, DACs and ADC) and must be connected to J33 (0.1” pitch) connector. Fan will be turned on when board heats up to 55°C and will be turned off when the temperature reduces to 45°C.

Figure 10 FAN control temperature hysteresis


Measured temperature value can read by using LimeSuiteGUI as described in chapter “3.13 Reading Board Temperature”. LimeSDR-QPCIe board comes with a dedicated 60mm DC FAN mounting space. Three M3 exposed copper holes (connected to board GND plane) and a space for a standoff are provided and are shown in Figure 11. The hole centre to hole centre distance is 50mm.The FAN is controlled via J33 (0.1” pitch) connector which can provide either 12V (default) or a 5V supply rail. The gate of the FAN driving MOSFET is connected to IC29 (FPGA) pin J22 (2.5V/3.3V bank).


Figure 11 LimeSDR-QPCIe v1.2 Dedicated FAN mounting space

2.2.8 Clock Distribution

LimeSDR-QPCIe board clock distribution block diagram is presented in Figure 12.

Figure 12 LimeSDR-QPCIe v1.2 board clock distribution block diagram


2.2.8.1 Main clock sources

There are various crystal oscillators with various frequencies mounted on LimeSDR-QPCIe board. The programmable clock generator IC37 (Si5351C [link]) can generate any reference clock frequency, starting from 8 kHz – 160 MHz, for FPGA and LMS PLLs. A real-time clock (RTC) chip (IC50) is also included on the LimeSDR-QPCIe board. The output of IC50 is connected to the FPGA pin H17. Main clock sources and destinations are listed in Table 36.

Table 36. LimeSDR-QPCIe clock sources and destinations
Src. Dest. Schematic net name Freq. I/O standard FPGA pin Description
Clk. Gen. (IC57) FPGA SI_CLK0 8kHz-160MHz 2.5/3.3V P22
SI_CLK1 8kHz-160MHz 2.5/3.3V P23
EXT_GXB_CLK_P 8kHz-160MHz LVDS P8 Single-ended converted to differential through IC56
EXT_GXB_CLK_N N7
Clk. Buff. (IC52) SI_CLK4 8kHz-160MHz - - Can be selected as IC52 CLKin1 clock source
FPGA SI_CLK6 8kHz-160MHz 1.5V AB18
SI_CLK7 1.5V AC15
FX3 (IC42) FPGA FX3_PCLK 66MHz, 100MHz 1.5V AB16
GNSS (IC48) FPGA GNSS_TPULSE * 3.3V/2.5V T23
RTC (IC50) FPGA RTC_32KHZ 32kHz 1.5V H17
XO5 FPGA CLK100_FPGA 100MHz 1.5V Y15
XO6 FPGA CLK125_FPGA 125MHz 1.5V L15
XO7 FPGA CLK125_FPGA_TOP_P 125MHz LVDS H19
CLK125_FPGA_TOP_N J18
XO8 FPGA CLK125_FPGA_BOT_P 125MHz LVDS AB14
CLK125_FPGA_BOT_N AC14
XO9 FPGA CLK125_FPGA_REF_P 125MHz LVDS R8
CLK125_FPGA_REF_N R7
FPGA DAC (IC40, IC41) DAC_CLK_WRT * 2.5/3.3V M29 Goes through clock buffer (IC21)
Clk. Buff. (IC52) FPGA CLK_LMK_FPGA_IN * 1.5V AB17
RFIC (IC1) FPGA LMS1_MCLK1 * 2.5/3.3V U22
LMS1_MCLK2 * 2.5/3.3V U21
FPGA RFIC (IC1) LMS1_FCLK1 * 2.5/3.3V Y30
LMS1_FCLK2 * 2.5/3.3V Y22
FPGA Clk. Buff. (IC52) LMK_CLK_FPGA_OUT * 2.5/3.3V N21
RFIC (IC2) FPGA LMS2_MCLK1 * 2.5/3.3V T24
LMS2_MCLK2 * 2.5/3.3V U23
FPGA RFIC (IC2) LMS2_FCLK1 * 2.5/3.3V W30
LMS2_FCLK2 * 2.5/3.3V AC29
FPGA DDR3 (IC33, IC34) DDR3_TOP_CK_P * Differential 1.5-V SSTL Class I M9
DDR3_TOP_CK_N * M8
FPGA DDR3 (IC35, IC36) DDR3_BOT_CK_P * Differential 1.5-V SSTL Class I Y13
DDR3_BOT_CK_N * AA14
FPGA DAC (IC40, IC41) DAC_CLK_WRT * 3.3V M29 Feeds both DAC through clock buffer (IC55)
ADC (IC37) FPGA ADC_CLKOUT_P * LVDS L14
ADC_CLKOUT_N * L13
FPGA ADC (IC37) ADC_CLK * 3.3/2.5V N30 Converted from single ended to LVDS through IC39
2.2.8.2 Clock buffer source selection

Clock buffer (IC52) presented in Figure 12 provides clock signals for following components:

  • LMS7002 transceivers (IC1, IC2);
  • FPGA (IC29) pin AB17;
  • Phase detector (IC53);
  • Clock generator (IC57);
  • U.FL connector J35 (REF CLK OUT label on board). To use this output 0R resistor R378 has to be fitted.


CLKin0 – to select this input as a source for Clock buffer (IC52) R375 resistor has to be removed (removed by default). As a source for this input one of the following high-precision crystal oscillators can be selected:

  1. XO1 – 30.72 MHz VCOCXO (precision: ±20 ppb stable);
  2. XO2 or XO3 – 30.72 MHz VCTCXO (precision: ±1 ppm initial, ±4 ppm stable);
  3. XO4 – 40 MHz VCTCXO (precision: ±1 ppm initial).

IC52 buffer CLKin0 clock source is selected by one of the 0402 size 0R resistor combinations, required modifications can be found in Table 37.

Table 37. Crystal oscillator selection for clock buffer (IC52)
Source for clock buffer (IC52) CLKin0 input 0R Fit 0R NF Comment
XO1 R364, R365 R379, R380, R382, R384 Default selection
XO2, X03 R379, R380 R364, R365, R382, R384
XO4 R382, R384 R364, R365, R379, R380

CLKin1 – to select this input as a source for Clock buffer (IC52) R375 resistor has to be fitted (removed by default). As a source for this input one of the following sources can be selected:

  1. Clock generator (IC57)
  2. U.FL Connector (J36)
  3. FPGA (IC29) output pin N21
Table 38. Source for clock buffer (IC52) CLKin1 input selection
Source for clock buffer (IC52) CLKin1 input Schematic net name 0R Fit 0R NF Comment
Clock generator (IC57) output CLK4 SI_CLK4 R374 R368, R372 Default selection
J36 U.FL Connector REF_CLK_IN R372 R368, R374, R389
FPGA (IC29) output pin N21 CLK_LMK_FPGA_OUT R368 R372, R374
2.2.8.3 VCTCXO clock tuning

VCTCXO can be tuned by on-board phase detector (IC53, ADF4002 [[2]]) or by 16-bit DAC (IC54). The on-board phase detector is used to synchronize on-board VCTCXO with external equipment (via J36 U.FL connector) to calibrate frequency error. At the same time only ADF or DAC can control VCTCXO. Both ADF and DAC are connected to FPGA_SPI0 interface. For details see chapter SPI interfaces. With valid configuration selection between ADF and DAC is done automatically. When board is powered, by default VCTCXO is controlled by DAC.

2.2.9 Power Distribution

LimeSDR-QPCIe board can be powered from several sources. The first power supply source option is 12V DC through a 2.5mm centre positive barrel connector. The second one is through a standard 6-pin PCIe power connector J38 (0.165” pitch). The last supply source option is the board edge PCIe connector.

LimeSDR-QPCIe board has complex power delivery network consisting of many different power rails with different voltages, filters, power sequences. LimeSDR-QPCIe board power distribution block diagram is presented in Figure 13 in two parts.

Figure 13 LimeSDR-QPCIe v1.2 board power distribution block diagrams

Power network power circuit ICs are presented in Figure 14 and Figure 15.

Figure 14 LimeSDR-QPCIe v1.2 board power ICs on TOP side
Figure 15 LimeSDR-QPCIe v1.2 board power ICs on BOTTOM side