METHOD AND SYSTEM FOR PROVIDING AUTOMATIC GATE BIAS AND BIAS SEQUENCING FOR FIELD EFFECT TRANSISTORS
First Claim
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;
dividing circuit comprising a means for biasing and variably compensating drift in the gate threshold voltage required to set the quiescent drain current, the dividing circuit being connected to the control circuit and controlling operation of the control circuit to maintain an essentially constant current at the drain in connection with a wake-up transition;
detecting means, operably connected to the RF output signal, for detecting the power level of the RF output signal and supplying a DC voltage representative of the detected output power level;
means for producing a variable reference voltage; and
adjusting means, connected to the detecting means, the variable reference voltage and the dividing circuit, for automatically adjusting the drain current based at least in part on a comparison of the supplied DC voltage and the reference voltage by an amount necessary to maintain essentially constant output RF power.
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Accused Products
Abstract
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.
14 Citations
3 Claims
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1. An RF amplifier circuit comprising:
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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; dividing circuit comprising a means for biasing and variably compensating drift in the gate threshold voltage required to set the quiescent drain current, the dividing circuit being connected to the control circuit and controlling operation of the control circuit to maintain an essentially constant current at the drain in connection with a wake-up transition; detecting means, operably connected to the RF output signal, for detecting the power level of the RF output signal and supplying a DC voltage representative of the detected output power level; means for producing a variable reference voltage; and adjusting means, connected to the detecting means, the variable reference voltage and the dividing circuit, for automatically adjusting the drain current based at least in part on a comparison of the supplied DC voltage and the reference voltage by an amount necessary to maintain essentially constant output RF power. - View Dependent Claims (2, 3)
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Specification