Integrated attenuation elements

Claim 1

A controllable attenuation circuit arrangement comprising: an attenuation element comprising a semiconductor body of one conductivity type having a pair of opposite surfaces, three zones of the opposite conductivity type provided in one of said surfaces, a first of said three zones serving as an output for the high frequency signals, a second of said three zones serving as an input for the high frequency signals, and the third of said zones serving as a control zone, and a contact electrode carried on said semiconductor body on the surface opposite to that having said three zones; means for applying a first control signal between said first zone and said contact electrode and between said second zone and said contact electrode, tHe amplitude of said first control signal being variable in such a manner that for minimum attenuation said first control signal has a limit value at which the p-n junctions between said input and output zones and said semiconductor body are biased in the forward direction and for increasing attenuation up to a maximum attenuation the amplitude drops to a value at which said p-n junctions do not conduct control current; means for decoupling said contact electrode with respect to ground for high frequencies; means for coupling said control zone to ground for high frequencies; and means for applying a second control signal between said control zone and said contact electrode, the amplitude of said second control signal being variable in such a manner that for a minimum attenuation said second control signal has a limit value at which the p-n junction between said control zone and said semiconductor body does not conduct current and for increasing attenuation up to a maximum attenuation the value of said second control signal increases with a polarity at which said p-n junction continuously conducts current to an increasing extent.