METHOD AND SYSTEM FOR PROVIDING AUTOMATIC GATE BIAS AND BIAS SEQUENCING FOR FIELD EFFECT TRANSISTORS

摘要

A feedback gate bias circuit for use in radio frequency amplifiers to more effectively control operation of LDFET, GaNFET, GaAsFET, and JFET type transistors used in such circuits. A transistor gate bias circuit that senses drain current and automatically adjusts or biases the gate voltage to maintain drain current independently of temperature, time, input drive, frequency, as well as from device to device variations. Additional circuits to provide temperature compensation, RF power monitoring and drain current control, RF output power leveler, high power gain block, and optional digital control of various functions. A gate bias circuit including a bias sequencer and negative voltage deriver for operation of N-channel depletion mode devices.

主权项

1. An RF amplifier circuit comprising:
FET for receiving a RF input signal and generating an amplified RF output signal, the FET having a gate, drain, and source; control circuit, connected to the gate and drain of the FET, for controlling the current at the drain and comprising a means for biasing and variably compensating drift in the gate threshold voltage required to set the quiescent drain current, the control circuit being adapted to maintain an essentially constant current at the drain in connection with a wake-up transition; RF input detecting means, operably connected to the RF input signal, for detecting the power level of the RF input signal and supplying a first DC voltage representative of the detected RF input power level; means for producing a variable reference voltage; comparing means, operably connected to the RF input detecting means and the variable reference voltage, for comparing the supplied first DC voltage to the variable reference voltage; and switching means, operably connected to the comparing means, for turning off the FET based at least in part on a comparison of the supplied first DC voltage and the variable reference voltage.