TH71101

315/433MHz

FSK/ASK Receiver

39010 71101

Page 4 of 21

Data Sheet

Rev. 018

Jun/13

1.3

Block Diagram

Fig. 1: TH71101 block diagram

1.4

Mode Configurations

ENRX

Mode

Description

0

RX standby

RX disabled

1

RX active

RX enable

Note: ENRX are pulled down internally

1.5

LNA GAIN Control

Mode

Description

< 0.8 V

HIGH GAIN

LNA set to high gain

> 1.4 V

LOW GAIN

LNA set to low gain

Note: hysteresis between gain modes to ensure stability

1.6

Frequency Planning

Frequency planning is straightforward for single-conversion applications because there is only one IF that

can be chosen, and then the only possible choice is low-side or high-side injection of the LO signal (which is

now the one and only LO signal in the receiver).

The receiver’s single-conversion architecture requires careful frequency planning. Besides the desired RF

input signal, there are a number of spurious signals that may cause an undesired response at the output.

Among them is the image of the RF signal that must be suppressed by the RF front-end filter.

MIX1

12

IN_LNA

4

31

8

5

6

7

11

IF

13

17

27

28

26

IF

10

9

LO

25

BIAS

30

VCO1

PFD

RO

22

RO

LF

29

CP

32

18

19

OAP

OAN

OUT_OA

OA

20

LNA

3

2

1

MIX2

14

15

16

23

24

OUTP

OUTN

MIX3

IFA

21

DIV_16