US 4,843,358 A · Electrically positionable short-circuits

Abstract

An electrical short-circuit for alternating-current (ac) microwave signals is physically positionable in direct response to an electrical bias control without an intermediary electromechanical converter. The electrically positionable short circuit includes at least first and second doped regions in a semiconductor, separated by a region in which the short circuit is formed between the doped regions by the bias. A first embodiment comprises discrete diodes connected between conductors at different locations, the discrete diodes having different forward junction voltages, so that varying the common bias voltage varies the number of conducting diodes and thus positions the short circuit in a stepwise manner. A FET embodiment includes various discrete MOSFETs having different conduction threshold voltages, and having their sources and drains connected at various points to the conductors to be short-circuited, so that variations of a common gate bias voltage selectively render one or more of the FETs conductive, thereby stepwise positioning the short-circuit. Distributed PIN and MOSFET structures provide continuous short circuit positioning as a monotonic function of bias. Two distinct modes of operation, pinchoff/resistive and a resistive/below-threshold are possible for the distributed FET embodiment. The electrically positionable short-circuit can be coupled to the conductors of a transmission line for effecting tuning, or can be coupled to a transmission line in such a way as to vary the signal path length and thereby provide phase shift.

Claims17

Dependent claims

An electrically-positionable short circuit for presenting a short circuit to a source of alternating current which short circuit is controllable in position in response to the magnitude of an electrical bias produced by a bias source which is independent of said alternating current source, comprising:

first and second approximately parallel conductive means;
first connection means coupled to said first and second conductive means, said first connection means being adapted for coupling said first and second conductive means to said source of alternating current;
semiconductor means physically positioned between and extending between said first and second conductive means at least frist and second pairs of distinct locations thereon, one of each pair of locations being associated with one of said first and second conductive means, and the other of each pair of locations being associated with the other of said first and second conductive means, said semiconductor means being responsive to the magnitude of said electrical bias in such a manner that at a first magnitude of said electrical bias of a given polarity, a short circuit path is established, at least for said alternating currents, between said first pair of distinct locations and a high impedance path is established, at least for said alternating currents, between said second pair of physically distinct locations, and such that, at a second magnitude, greater than said first magnitude, of said electrical bias, and of said given polarity, a short circuit path is established, at least for said alternating currents, between said second pair of distinct locations;
and
second connection means coupled to said semiconductor means, said second connection means being adapted for coupling said semiconductor means to said bias source for coupling said electrical bias to said semiconductor means for establishing, by the magnitude of said electrical bias of said given polarity, the impedance, at least for said alternating current, between said second pair of distnct locations.

2 more elements

Dependencies are inferred from the claim text.

Electrically positionable short-circuits

Life of this patent

Electrically positionable short-circuits

Life of this patent

Abstract

Claims17