Circuit Description

This circuit includes the following functions

Three symmetrical and gain controlled wide band amplifier stages, which are extremely stable by quasi DC coupling without feedback

Averaged AGC with discharge control circuit

AGC voltage generator

Quasi parallel sound operation

High phase accuracy of the carrier signal processing, independent from AM

Linear quadrature demodulator

Sound–IF–amplifier stage with impedance converter

AM–Demodulation (TDA4445B only)

Carrier controlled demodulator

Audio frequency stage with impedance converter

Averaged low pass AGC

Features

Very high input sensitivity

Excellent signal to noise ratio

Fast averaged AGC

IF amplifier can be switched off for VTR mode

Output signal stabilized against VSvariations

Very few external components

TDA4445B additional

Targeting bistandard applications (B/G and L)

Alignment free AM demodulator

Low AM distortion