Amplifiers using gated diodes

A circuit for amplifying signals, the circuit comprising:

• a control line;
• a control voltage generator comprising a reference voltage generating circuit and a voltage output circuit;
• a two terminal semiconductor device having first and second terminals, the first terminal coupled to a signal line, and the second terminal coupled to the control line, wherein the two terminal semiconductor device is configured to have a capacitance when a voltage on the first terminal relative to the second terminal is in a first voltage range and to have a lower capacitance when the voltage on the first terminal relative to the second terminal is in a second voltage range, wherein said first and second voltage ranges are defined by a threshold voltage, wherein the control line is configured to be coupled to a control signal and wherein the signal line is configured to be coupled to an input signal;
• and
• an isolation device intermediate the signal line and the two terminal semiconductor device, the isolation device having an input, an output and a control terminal, the input of the isolation device coupled to the signal line and the output of the isolation device coupled to the first terminal, wherein the output of the isolation device is configured to be an output of the circuit, and whereby the control terminal of the isolation device is coupled to the control voltage generator;
• wherein the reference voltage generating circuit is configured to generate the reference voltage determined as a function of a magnitude of the voltage on the signal line and a threshold voltage of the isolation device and to supply the reference voltage to an input of the voltage output circuit;
• and
• wherein the voltage output circuit is configured to supply a control voltage to the control terminal of the isolation device, the voltage output circuit being configured to generate the control voltage based on a comparison of the reference voltage and a feedback output voltage.