Abstract: A voltage controlled resistor includes an operational transconductance amplifier (OTA) including first and second linearizing diodes which not only optimize signal-to-noise distortion levels but also represent the AC impedance from the inverting input to ground. The OTA turns on and off in response to the amount of gain control current being supplied thereto. A Darlington transistor is coupled to the output of the OTA for providing a low impedance buffered output. A first resistor provides current flow through the diodes. A feedback resistor supplies and controls bias current to one of the diodes. A third resistor maintains bias to the Darlington pair when the OTA output approaches open circuit output impedance conditions.

Abstract: A circuit for peak limiting an audio signal comprises a first "M" derived filter, a first clipping circuit, a second-order low pass filter, a second clipping circuit and a second "M" derived filter. Each "M" derived filter includes a series resonant shunt leg for eliminating clipping harmonics within selected frequency ranges depending upon the resonant frequency of each shunt leg.