EVB71101 Просмотр технического описания (PDF) - Melexis Microelectronic Systems

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EVB71101

315/433MHz Receiver Evaluation Board Description

Melexis Microelectronic Systems  

1.3 Block Diagram

EVB71101

315/433MHz Receiver

Evaluation Board Description

12

34

5

6

7

8

9 10 11 12 13

21

14 15

16

IN_LNA

31

LNA

32 30

MIX1

IF

MIX2

IF

IFA

LO

MIX3

DIV_16

PFD

RO

VCO1

CP

BIAS

29 LF

26 RO

25 27

28

Fig. 1: TH71101 block diagram

22

17

OUTP

23

OUTN

24

OAP

OA

20

OAN

19

OUT_OA

18

1.4 Mode Configurations

ENRX

Mode

0

RX standby

1

RX active

Note: ENRX are pulled down internally

Description

RX disabled

RX enable

1.5 LNA GAIN Control

VGAIN_LNA

< 0.8 V

Mode

HIGH GAIN

> 1.4 V

LOW GAIN

Note: hysteresis between gain modes to ensure stability

Description

LNA set to high gain

LNA set to low gain

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.

39012 71101 01

Rev. 011

Page 4 of 14

EVB Description

June/07

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