REGULATION OF VOLTAGE AND CURRENT FOR COMMON GATE CONNECTED TRANSISTOR CIRCUIT

摘要

A circuit for maintaining a constant voltage across and constant current through an RF cavity includes a RF cavity comprising a common-gate or common-base transistor associated with a current control circuit maintains a constant current flowing through the RF cavity. The current control circuit has a current control BJT associated with the RF cavity and a resistor between the emitter of the current control BJT and the negative source voltage of the RF cavity. The current control BJT and resistor operate as a current source or sink as necessary to maintain a constant current flow through said RF cavity. A constant voltage regulation portion of the circuit maintains a constant voltage across the RF cavity and includes a zener reference diode and a voltage regulation BJT. The zener reference diode has an associated isolation operational amplifier circuit for isolating the zener reference diode from current fluctuations at the source while permitting the zener reference diode to respond to voltage difference changes across the RF cavity. The zener reference diode and voltage regulation BJT control voltage applied to the RF cavity. The current control circuit and constant voltage regulation circuit automatically maintain a constant current passing through and constant voltage difference across the RF cavity.