XR-2211 Ver la hoja de datos (PDF) - Exar Corporation

Número de pieza

componentes Descripción

Fabricante

XR-2211

FSK Demodulator Tone Decoder

Exar Corporation 

XR-2211

Linear FM Detection

XR-2211 can be used as a linear FM detector for a wide

range of analog communications and telemetry

applications. The recommended circuit connection for

this application is shown in Figure 13. The demodulated

output is taken from the loop phase detector output (pin

11), through a post-detection filter made up of RF and CF,

and an external buffer amplifier. This buffer amplifier is

necessary because of the high impedance output at pin

11. Normally, a non-inverting unity gain op amp can be

used as a buffer amplifier, as shown in Figure 13.

The FM detector gain, i.e., the output voltage change per

unit of FM deviation can be given as:

VOUT

+

R1·VREF

100·R0

where VR is the internal reference voltage (VREF = VCC /2

- 650mV). For the choice of external components R1, R0,

CD, C1 and CF, see the section on design equations.

V+

1

20K

20K

REF

Voltage

Output

10

Input

2

10K 10K

B

From

VCO

B’

Lock

Detect

Filter

3

6

Lock Detect

Outputs

5

Internal Voltage

Reference

Input Preamplifier

and Limiter

Quadrature

Phase Detector

Lock Detect

Comparator

4

Ground

2K

2K

A

Timing

Capacitor

A’

13 C0 14

B B’

A

From

VCO

A’

8

11

FSK

Loop Comparator

Detector Input

Output

12

R0

Timing

Resistor

8K

Voltage Controlled

Oscillator

Loop Phase Detector

Figure 14. Equivalent Schematic Diagram

FSK Comparator

7

FSK

Data

Output

Rev. 3.01

18

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