Patent ID: 7019566

Claim:
A switch comprising an input with a first and a second input line and an input stage comprising first, second, third and fourth current controlled PNP-transistors and first, second, third and fourth resistors, and an output comprising a first and a second output line, and wherein said switch is arranged to receive a constant voltage on said input and produce a variable voltage on said output, wherein said first resistor is connected to said first input line and further to the emitter of said first transistor, said second resistor is connected to said first input line and further to the emitter of said second transistor, said third resistor is connected to said second input line and further to the emitter of said third transistor, said fourth resistor is connected to said second input line and further to the emitter of said fourth transistor, the collector of said first and fourth transistor is connected to said second output line, the collector of said second and third transistor is connected to said first output line, and first, second, third and fourth constant current sources are connected to the bases of said first, second, third and fourth transistor, respectively so that said transistors are conductive, and first, second, third and fourth alternating current sources are connected to the emitters of said first, second, third and fourth transistor, respectively, so that the transistors alternately are conducting current from emitter to collector and from collector to emitter.