RF Network Control

LimeSDR XTRX RF network contains matching networks, RF switches, loopback variable attenuator and U.FL connectors (X1, X3 - TX and X2, X4 - RX) as shown in Figure 6.

Figure 6. LimeSDR XTRX v1.3 RF diagram

LMS7002M RF transceiver TX and RX ports has dedicated matching network which determines the working frequency range. More detailed information on LMS7002M RF transceiver ports and matching network frequency ranges is listed in the Table 3.

Table 3. LMS7002M RF transceiver ports and matching networks frequency ranges

LMS7002M RF transceiver port	Frequency range
TX1_1, TX2_1	3.3 GHz – 3.8 GHz
TX1_2, TX2_2	30 MHz – 1.9 GHz
RX1_H, RX2_H	3.3 GHz – 3.8 GHz
RX1_W, RX2_W	700 MHz – 2.6 GHz
RX1_L, RX2_L	300 MHz – 2.2 GHz

RF network switches are controlled via 2.4V logic signals. This is achieved by resistor dividers connected between FPGA (TX_SW, RX_SW1, RX_SW2) and switch control pin (TX_SW_DIV, RX_SW1_DIV, RX_SW2_DIV). RF network control signals are described in the Table 4.

Table 4. RF network control signals

Component	Schematic signal name	I/O standard	FPGA pin	Description
SKY13330-397LF(IC5 and IC6)	TX_SW/TX_SW_DIV	3.3V	P1	FPGA 3.3V logic level signal divided to 2.4V logic level.
SKY13414-485LF(IC3 and IC4)	RX_SW1/RX_SW1_DIV	3.3V	K3	FPGA 3.3V logic level signal divided to 2.4V logic level.
	RX_SW2/RX_SW2_DIV	3.3V	J3	FPGA 3.3V logic level signal divided to 2.4V logic level.