U.S. Philips Corporation

Winfrid B Jansen

Wolfgang Nolde

Hermann Jabs

Wilfried E Knop

An amplifier arrangement with controllable gain comprising two differential amplifiers which are connected in parallel at their inputs and outputs and which have different gain factors which can be varied oppositely. The gain of one of said differential amplifiers is reduced in that a first resistor is connected between its input terminals and a second resistor is connected between at least one of said input terminals and the corresponding input terminal of the other differential amplifier. As a result, the input signal to this amplifier is subject to a voltage division enabling the input swing to be increased.

Amplifier arrangement with controllable gain

An FM stereo receiver has a loop having a negative loop gain for the pilot signal contained in the input signal in the form of a frequency modulation. As a result thereof the frequency modulation of the input signal is reduced or suppressed by the pilot signal, so that the interference introduced by this pilot signal is also reduced or suppressed.

FM stereo receiver

A circuit for reducing the distortion in an FM quadrature demodulator. A non-linear circuit stage is connected after the quadrature demodulator, whose characteristic has an inverse curve form like the demodulator characteristic. If the FM quadrature demodulator uses a resonant circuit to generate a frequency-dependent phase shift and has two outputs in phase opposition, the non-linear circuit stage can be formed by two diode branches through which the output currents of the quadrature demodulator flow. The voltage difference at these two diode branches supplies the output signal with the non-linear distortions largely removed.

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Ellerbek, Germany

Winfrid B Jansen