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