Variable impedance circuit employing an RIS field effect transistor

Claim 1

A variable impedance circuit comprising a field effect transistor formed from a substrate in which a source and a drain region are formed, an insulating layer formed on said substrate between said source and drain, a resistive gate layer formed on said insulating layer between said source and drain, a first gate electrode connected to a first end of said resistive gate layer which is near said source, a second gate electrode connected to a second end of said resistive gate layer which is near said drain, a back gate electrode connected to said substrate of said field effect transistor, a voltage source connected to said back gate electrode, a first phase inverter connected to said drain, a first adder circuit including a first variable resistor connected to said first phase inverter, a control voltage source connected to said first adder and the output of said first adder connected to said second gate electrode, a second phase inverter and amplifier circuit connected to the output of said first phase inverter circuit, a second adder circuit including a second variable resistor connected to said second phase inverter circuit, the output of said second adder and said control voltage source connected to said first gate electrode, a load connected across said source and drain, and an input voltage connected across said source and drain.