Trw Limited

Arvind K Sharma

Kevin Wesley Kobayashi

Barry Ross Allen

Aaron K Oki

Duncan M Smith

The present invention provides a switched-line phase shifter (,) for creating a differential phase shift between switched transmission paths (,). A switched-line phase shifter (,) incorporates Schiffman sections (,) of lengths which are non-integer multiples of quarter-wavelength. The lengths of the Schiffman sections (,) are chosen such that no isolation points, which result from frequencies at which the effective electrical length of one of the transmission paths (,) is an integer multiple of &lgr;/2, occur over the operating frequency range of the phase shifter (,). The present invention also provides a space-efficient implementation of a switched-line phase shifter (,) which utilizes switches (,) between Schiffman subsections (,) to alternately combine and isolate the Schiffman subsections (,) thereby alternately creating effective Schiffman sections of greater and lesser length respectively.

Compact phase shifter circuit using coupled lines

A quenchable VCO that is adapted to be used in switched band synthesizer applications. The VCO may be formed from a heterojunction bipolar transistor (HBT) in a common collector configuration. A quenching circuit which includes a p-i-n diode, is electrically coupled in series with the collector of the HBT. The p-i-n diode is adapted to be monolithically integrated with the HBT. Since the p-i-n diode is electrically connected to the collector of the HBT, as opposed to the base and emitter terminals of the HBT, which forms the main oscillator feedback loop, the Q-factor of the p-i-n diode will have relatively less loading on the phase noise of the HBT oscillator. Moreover, since the p-i-n diode is isolated from the base-emitter junction, the configuration will result in reduced frequency pulling and generation of spurious oscillation and transient effects due to the switching of the p-i-n diode quenched circuit. The use of a p-i-n diode for quenching of VCO also provides other inherent advantages over other types of semi-conductor switches, such as FET, Schottky diodes, PN diodes for quenchable VCO applications because p-i-n diodes are relative insensitive to RF and noise modulation. Because the p-i-n diode can be constructed from existing HBT collector-base MBE epitaxy layers, the quenching circuit can be manufactured relatively inexpensively.

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Torrance, CA, United States of America

Arvind K Sharma