Method and circuit for controlling a resistance of a field effect transistor configured to conduct a signal with a varying voltage

A circuit for controlling a resistance of a first field effect transistor configured to conduct a signal with a varying voltage, comprising:

• a second field effect transistor having a source and a drain, the second field effect transistor configured to have the signal with the varying voltage applied to one of the source and the drain;
• a first portion of the circuit for tracking a variation in a voltage potential between the source and the drain of the second field effect transistor;
• and
• a second portion of the circuit for changing, in response to the variation, a first voltage applied to a gate of the first field effect transistor to control the resistance of the first field effect transistor.

A method for controlling a resistance of a field effect transistor conducting a signal with a varying voltage, comprising the steps of:

• (1) applying the signal with the varying voltage to a bridge circuit;
• (2) tracking a variation in a voltage potential between a first node and a second node of the bridge circuit;
• and
• (3) changing, in response to the variation, a voltage applied to a gate of the field effect transistor to control the resistance of the field effect transistor;
• wherein the field effect transistor is disposed outside the bridge circuit.

A circuit for controlling a resistance of a field effect transistor conducting a signal with a varying voltage, comprising:

• a bridge circuit having a first node and a second node, the bridge circuit configured to have the signal with the varying voltage applied to the first node;
• a first portion of the circuit for tracking a variation in a voltage potential between the first node and the second node;
• and
• a second portion of the circuit for changing, in response to the variation, a voltage applied to a gate of the first field effect transistor to control the resistance of the field effect transistor;
• wherein the field effect transistor is disposed outside the bridge circuit.