TDA5211 データシートの表示（PDF） - Infineon Technologies

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TDA5211

ASK/FSK Single Conversion Receiver

Infineon Technologies 

TDA 5211

Functional Description

3.3 Functional Block Diagram

VCC

IF

Filter

LNO

6

MI

MIX IFO

8 9 12

LIM

LIMX

17 18

MSEL

15

FFB

OPP

22

21

SLP

SLN

19 20

LNI 3

RF

LNA

TAGC 4

LIMITER

FSK

PLL Demod

-

+ FSK

- ASK

+

TDA 5211

OTA

-

SLICER

25 DATA

OP

+

PEAK 26 PDO

DETECTOR

23 THRES

VCC 14

DGND

13

2,7 5,10

:1/2

VCO

: 128 / 64

Φ

DET

Loop

Filter

11

16

CRYSTAL

OSC

1

28

UREF

AGC

Reference

Bandgap

Reference

27

24 3VOUT

VCC AGND

(FSEL)

CSEL

Crystal

Figure 3-2 Main Block Diagram

PDWN

Functional_diagram_5211.wmf

3.4 Functional Blocks

3.4.1 Low Noise Amplifier (LNA)

The LNA is an on-chip cascode amplifier with a voltage gain of 15 to 20dB. The

gain figure is determined by the external matching networks situated ahead of

LNA and between the LNA output LNO (Pin 6) and the Mixer Inputs MI and MIX

(Pins 8 and 9). The noise figure of the LNA is approximately 3dB, the current

consumption is 500µA. The gain can be reduced by approximately 18dB. The

switching point of this AGC action can be determined externally by applying a

threshold voltage at the THRES pin (Pin 23). This voltage is compared internally

with the received signal (RSSI) level generated by the limiter circuitry. In case

that the RSSI level is higher than the threshold voltage the LNA gain is reduced

and vice versa. The threshold voltage can be generated by attaching a voltage

divider between the 3VOUT pin (Pin 24) which provides a temperature stable

3V output generated from the internal bandgap voltage and the THRES pin as

described in Section 4.1. The time constant of the AGC action can be deter-

Wireless Components

3-9

Specification, May 2001

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