Hughes Aircraft Company

Al Thiele

Khalid Karimullah

Sai Kwok

A power level control circuit for the power amplifier of a mobile cellular unit does not require a matched diode pair yet is simple in design. A sampling device, such as a directional coupler or sampling capacitor, connected to an output of the power amplifier provides a sampled RF signal output. An impedance is connected to the sampling device, and the sampling device forms a RF attenuator. A tunnel diode detector is connected to the sampling device for generating a detected d.c. output signal. Power level control (PLC) circuitry compares the detected d.c. output signal from the tunnel diode detector with a selected power level control reference signal and generates a feedback signal to the RF power amplifier to control the power level output from the amplifier. The dynamic range of this basic circuit is increased by switched attenuators, switched parallel detectors with scaled attenuation factors, or a controlled varactor diode used to change the RF coupling to the diode detector.

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San Diego, CA, United States of America

Al Thiele