Circuit arrangement for decoding a frequency modulated stereo radio signal

A correcting amplifier for connection between a FM demodulator and a stereo decoder and matrix, in which matrix two reproduction signals are formed by sum and difference formation from a sum signal component of the output signal of the FM demodulator and a difference signal component converted from an auxiliary carrier frequency state to the audio frequency state by a synchronous demodulator connected to said stereo decoder, said correcting amplifier comprising:

• a high gain operational amplifier having an inverting input, a noninverting input and an output;
• and
• a RC feedback circuit connecting said output and said inverting input to provide a linear frequency response for the sum signal component and the difference signal component,
• said operational amplifier comprising
• a differential amplifier including first and second transistors each having a base, an emitter and a collector, said emitters connected together, said base of said first transistor connected to receive the output signal of the FM demodulator,
• a current reflector connecting said collectors of said first and second transistors to a reference potential,
• a constant current source connecting said emitters to a supply potential,
• a first resistor,
• a second resistor,
• a capacitor, and
• an amplifier transistor including a base connected to said collector of said first transistor, an emitter connected to the reference potential, and a collector connected to the supply potential via said first resistor and to said base of said second transistor via said second resistor and to the reference potential via said capacitor, and said collector providing the corrected signal output for connection to the stereo decoder.