Patent ID: 6249552
Filing Date: 2001-06-19
Classification: H04L

Abstract:
An audio frequency recovery-DC restorer circuit, comprising:an operational amplifier having two inputs and an output;resistor circuitry arranged to supply a reference voltage signal Vref to said operational amplifier;a diode electrically connected to said output; anda capacitor connected in series to one of said inputs of said operational amplifier, wherein said capacitor couples a demodulated audio frequency baseband signal to the operational amplifier, the demodulated audio frequency baseband signal being in a filtered condition free of high frequency noise that may otherwise affect quality and having an average voltage level Vavg at a level,said operational amplifier being configured and arranged to clamp the demodulated audio frequency baseband signal above or below the Vref depending upon an orientation of the diode so as to set a new desired Vref and provide as output a clamped baseband signal whose amplitude and waveform is identical to the demodulated audio frequency baseband signal before the clamping except for having a new average voltage (new Vavg) that is at a level different from that of the average voltage of the demodulated audio frequency baseband signal because of the new desired Vref.