Celeritek

Pacific Monolithics

Wavetek Microwave, Inc.

Stephen C Cripps

Thomas R Allen

Gary J Policky

John R Anderson

A control network operates a GaAs FET with a quiescent current closer to the maximum output current, I.sub.max, than to zero current. An output network couples the FET to the load and is characterized as having a low impedance at a fundamental frequency and a high impedance lower than an open circuit impedance at at least the second harmonic frequency. As a result, the peak voltage on the output terminal is greater than two times the supply voltage. A preamplifier raises the level of the input signal so that it has a positive voltage peak when biased by the control network and applied to the input terminal. This overdrives the FET and produces an output current that is at the maximum output current level for a longer time during each cycle than the output current is at a minimum level. This enhances the effect of the output network to produce an output voltage spike on the FET that is several times the DC voltage. The amplifier is part of an amplifier system that also includes a switch coupled between the DC supply and the FET that is responsive to a control signal. A circuit is responsive to the input signal for generating the control signal appropriate for disconnecting the DC voltage supply from the FET when there is no input signal.

High efficiency RF power amplifier

A radio frequency ('RF') power sensor providing RF signal power sensing with reduced dependency upon its input signal power level includes multiple series-connected diodes for detecting the power of an input RF signal and providing an output voltage representing that power. The multiple series-connected diodes couple the input node shunted by an input load resistor to the output node shunted by an output filter capacitor. Using multiple series-connected diodes results in reduced reverse bias voltages across the diodes (presented by the charged output filter capacitor), thereby increasing their junction capacitances. These increased junction capacitances, in turn, result in reduced fractional changes thereof (e.g. capacitance 'modulation') over changes in the input RF signal power. This reduction in fractional capacitance changes as a function of input signal power variations, further in turn, results in reduced input signal power dependency of the sensors' impedances and sensitivities. Therefore, the power detection performed by the diodes becomes more predictable, e.g. more linear, over a broader input RF signal power range.

RF power sensor having improved linearity over greater dynamic range

The operating temperature of the active region of an RF semiconductor device such as a microwave hybrid circuit having a gallium arsenide field-effect transistor therein is determined by measuring signal gain of the device at variable times following application of bias voltage to the device. Bias voltage is applied in response to a constant duty cycle pulse train from which are derived a sample-and-hold command pulse and a synchronized bias control pulse.

Method and means for measuring operating temperature of semiconductor

A field effect transistor microwave circuit device includes first and second field effect transistors having common source connections with a pair of coupled transmission lines connecting the drain of a first transistor to the source of the second transistor and the source of the first transistor to the gate of the second transistor. The cross coupled transmission lines function as a balun between the transistors. The device is formed in III-V semiconductor and has an increased operating range in microwave frequencies. In alternative embodiments, the balun is connected to the circuit output thereby permitting the cascading of a plurality of FET devices. The balun can be integrated into the device structure or connected as a discrete element in a hybrid circuit arrangement.

Multiple FET device having direct-coupled stages for improved microwave

A microstrip balun comprises a ceramic substrate having a ground plane on one surface and three elongated conductive strips on the opposite surface. First ends of the outer strips are interconnected with the ground plane through vias in the substrate. The unbalanced signal input is applied to the ground plane near the vias and one end of the inner strip. The other ends of the outer strips are interconnected, and the balanced signal output is taken at this interconnection and at one end of the inner strip. A portion of the ground plane beneath portions of the strips can be removed.

Growing community of inventors

Sunnyvale, CA, United States of America

Stephen C Cripps