Optically controlled microwave switch and signal switching system
First Claim
1. An optoelectronic microwave switching system comprising:
- means for supplying a microwave signal;
transmission means for conveying said microwave signal;
switch means for receiving said microwave signal and for operating in an on state to pass said signal therethrough and in an off state to block passage of said signal therethrough, said switch means including a field-effect transistor having a gate electrode, a source electrode and a drain electrode one of said source and drain electrodes being connected to said transmission means, and at least two photodiodes, each having an anode and a cathode, the anodes of two of said photodiodes being coupled to said gate electrode of said field-effect transistor, the cathodes of said two photodiodes being respectively coupled to the source and drain electrodes of said field-effect transistor, said two photodiodes being responsive to optical energy to control the state of operation of said switch means;
a light source remote from said switch means for selectively supplying optical energy; and
light transmission means for conveying optical energy from said remote light source to said photodiodes so as to activate said photodiodes to control the state of operation of said switch means.
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Accused Products
Abstract
Disclosed is an optically activated microwave switch (10) which includes a field-effect transistor (12) that is switched between conducting and nonconducting states by a photodiode (14) that is connected between the field-effect transistor gate and drain electrode and a photodiode (16) that is connected between the field-effect transistor gate and source electrode. The circuit is configured and arranged for switching unbiased sinusoidal microwave signals of a frequency as high as approximately 10 gigahertz. A cascade arrangement of switches (10) provides increased signal handling capability in situations in which a single switch cannot be employed. Monolithic integrated circuit realizations of both single stage and cascaded stage arrangements are disclosed in which the semiconductor substrate is GaAs, the field-effect transistors are metal-semiconductor field-effect transistors and the photodiodes are interdigitated metal-semiconductor-metal devices.
31 Citations
34 Claims
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1. An optoelectronic microwave switching system comprising:
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means for supplying a microwave signal; transmission means for conveying said microwave signal; switch means for receiving said microwave signal and for operating in an on state to pass said signal therethrough and in an off state to block passage of said signal therethrough, said switch means including a field-effect transistor having a gate electrode, a source electrode and a drain electrode one of said source and drain electrodes being connected to said transmission means, and at least two photodiodes, each having an anode and a cathode, the anodes of two of said photodiodes being coupled to said gate electrode of said field-effect transistor, the cathodes of said two photodiodes being respectively coupled to the source and drain electrodes of said field-effect transistor, said two photodiodes being responsive to optical energy to control the state of operation of said switch means; a light source remote from said switch means for selectively supplying optical energy; and light transmission means for conveying optical energy from said remote light source to said photodiodes so as to activate said photodiodes to control the state of operation of said switch means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 17, 18, 19, 20, 21, 22, 23)
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13. An optically activated microwave switching apparatus comprising:
a plurality of cascade connected optoelectronic switch stages, each switch stage including a field-effect transistor and two photodiodes, the anodes of each of said two photodiodes being connected to the gate of said field-effect transistor and the cathodes of said two photodiodes being respectively connected to the drain and source of said field-effect transistor. - View Dependent Claims (14, 15)
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24. An integrated circuit microwave frequency switch comprising:
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a semi-insulating substrate formed of a Group III-V semiconductor, said substrate having at least one substantially planar surface; a metal-semiconductor field-effect transistor including spaced apart source and drain metallizations formed on said substantially planar surface of said substrate and a gate metallization that extends along said substantially planar surface of said substrate in spaced-apart juxtaposition with said source and drain metallizations, said metal-semiconductor field-effect transistor exhibiting a first drain-to-source conduction state when the difference in electrical potential between said gate metallization and both said drain and source metallizations is less than a predetermined amount and exhibiting a second drain-to-source conduction state when the electrical potential at said gate metallization differs from the electrical potential at said source and drain metallizations by at least said predetermined amount; at least two metal-semiconductor-metal photodiodes formed on said planar surface of said substrate, said photodiodes being electrically interconnected with said gate electrode, said drain electrode and said source electrode of said metal-semiconductor field-effect transistor for controlling the potential at said gate metallization to maintain said field-effect transistor in said first drain-to-source conduction state when said photodiodes are illuminated and to maintain said metal-semiconductor field-effect transistor in said second drain-to-source conduction state when said metal-semiconductor-metal diodes are not illuminated; said gate metallization of said metal semiconductor field-effect transistor being electrically connected to the anode electrodes of said two metal-semiconductor-metal photodiodes, the cathode of one of said metal-semiconductor-metal photodiodes being connected to said drain metallization of said metal-semiconductor field-effect transistor, and the cathode of the other metal-semiconductor-metal photodiode being connected to said source metallization of said metal-semiconductor field-effect transistor, said metal-semiconductor-metal photodiodes maintaining said gate metallization at a potential that allows bidirectional current flow between said source and drain electrodes when said metal-semiconductor-metal photodiodes are illuminated said gate metallization being of relatively narrow strip-like geometry and extending beyond said drain and source metallization, said anodes of said metal-semiconductor-metal photodiodes being defined by substantially parallel spaced-apart extensions of said gate metallization that extend along said substantially planar surface of said substrate and being substantially orthogonal to said gate metallization, said cathodes of said first and second metal-semiconductor-metal photodiodes being defined by substantially parallel spaced-apart finger-like conductive regions that are interspersed with said substantially parallel spaced-apart finger-like extensions of said gate metallization. - View Dependent Claims (25, 26, 27, 28)
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29. An optoelectronic integrated microwave switch comprising:
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a substantially planar Group III-V semiconductor substrate; a plurality of n metal-semiconductor field-effect transistors, said plurality of n metal-semiconductor transistors being defined by a plurality of (n+1) substantially rectangular metallization regions and by a plurality of n strip-like metallization regions, said (n+1) metallization regions being formed on one surface of said substantially planar semiconductor substrate with boundary edges of said (n+1) metallization regions being substantially parallel to one another, said n strip-like metallization regions extending along said surface of said semiconductor substrate with each said strip-like metallization region being positioned between and substantially parallel to boundary edges of said different pair of said (n+1) metallization regions;
each said strip-like metallization region defining a gate electrode of a different one of n metal-semiconductor field-effect transistors with said pair of said (n+1) metallization regions that is associated with said strip-like metallization region defining the drain and source electrodes of that particular one of said n metal-semiconductor field-effect transistors; andn-pairs of Schottky barrier photodiodes formed on said surface of said semiconductor substrate, each pair of said Schottky barrier photodiodes being associated with and electrically connected to a different one of said strip-like metallization regions that defines a gate electrode of one of said n metal-semiconductor field-effect transistors and being associated with and electrically connected to the pair of metallization regions that define said source and drain electrodes of that particular one of said n metal-semiconductor field-effect transistors, said n-pairs of Schottky barrier photodiodes maintaining said n metal-semiconductor field-effect transistors in a first state of electrical conductivity when said n pairs of photodiodes are illuminated and a second state of electrical conductivity when said n pair of photodiodes are not illuminated. - View Dependent Claims (30, 31, 32, 33, 34)
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Specification