Japanese Patent JPS5646265

B2

An integrated attenuation element having a variable attenuation characteristic for high frequency signals comprises a semiconductor body of one conductivity type in one face of which there are arranged two zones of the other conductivity type. The semiconductor body has a contact electrode on the face opposite to that containing the two zones. One of the two zones serves as an input or as an output and the contact electrode serves as an output or as an input, respectively, for the high frequency signals, and the other of the two zones serves as a control zone. In a controllable attenuation circuit means are provided for applying a first control signal between the input and output of the attenuation element, the output being decoupled from ground with respect to high frequencies. The amplitude of the first signal is variable in such a manner that for minimum attenuation it possesses a value at which the p-n junction defining the input zone in the semiconductor body is biased in the forward direction, and to provide increased attenuation the first signal falls to a limiting value at which the p-n junction does not conduct. Means are also provided for applying a second control signal between the control zone, which is connected to ground for high frequencies, and the output. The amplitude of the second control signal is variable in such a manner that for minimum attenuation it possesses a value at which the p-n junction defining the control zone in the semiconductor body does not conduct current, and to provide increased attenuation up to a maximum amount, the signal increases with a polarity such that the p-n junction continuously conducts current to an increasing extent.

JP1018673A

October 31, 1981

January 24, 1973

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H03H1/00; H01L21/331; H01L21/822; H01L27/04; H01L29/00; H01L29/66; H01L29/73; H01L29/86; H03H7/25

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