US4481487A — Monolithic microwave wide-band VCO

Claim 1

Independent Claim 169 words

A monolithic wideband microwave voltage-controlled oscillator (VCO), comprising: a semi-insulating substrate; a doped semiconducting layer above said substrate; an FET comprising a source and drain in said semiconducting layer, and a gate interposed between said source and said drain; an input contact connected to one of said source and said drain, and an output contact connected to the other of said source and said drain; a varactor, comprising a first terminal and second terminal atop said semiconducting layer, said first terminal forming a barrier contact with said semiconducting layer, the portion of said semiconducting layer beneath said first terminal being sufficiently thin and sufficiently lightly doped that punch through between said first terminal and said substrate occurs at a lower voltage then does breakdown between said first terminal and said second terminal; and means for providing a bias voltage, connected to a first one of said terminals of said varactor, said gate of said FET being direct current connected to the other one of said terminals of said varactor.

Claim 2

Dependent Claim 169 words

A monolithic wideband microwave voltage-controlled oscillator (VCO), comprising: a semi-insulating substrate; a doped semiconducting layer above said substrate; an FET comprising a source and drain in said semiconducting layer, and a gate interposed between said source and said drain; an input contact connected to one of said source and said drain, and an output contact connected to the other of said source and said drain; a varactor, comprising a first terminal and second terminal atop said semiconducting layer, said first terminal forming a barrier contact with said semiconducting layer, the portion of said semiconducting layer beneath said first terminal being sufficiently thin and sufficiently lightly doped that punch through between said first terminal and said substrate occurs at a lower voltage then does breakdown between said first terminal and said second terminal; and means for providing a bias voltage, connected to a first one of said terminals of said varactor, said gate of said FET being direct current connected to the other one of said terminals of said varactor.

Claim 3

Dependent Claim 13 words

The VCO of claim 1, wherein said semi-insulating substrate comprises chromium-doped gallium arsenide.

Claim 4

Dependent Claim 14 words

The VCO of claim 2, wherein said doped semiconducting layer comprises n-type gallium arsenide.

Claim 5

Dependent Claim 16 words

The VCO of claim 3, wherein said doped semiconducting layer is less than one-half micron thick.

Claim 6

Dependent Claim 14 words

The VCO of claim 1, wherein said output contact is connect to said source.

Claim 7

Dependent Claim 30 words

The VCO of claim 5, wherein said source and drain each comprise respective pluralities of fingers, and said drain comprises a larger number of said fingers than does said source.

Claim 8

Dependent Claim 57 words

The VCO of claim 6, further comprising a capacitor including a first and second metal plates and a dielectric therebetween, said first plate of said capacitor being connected to said other one of said anode and said cathode of said varactor, and said second metal plate of said capacitor being connected to said drain of said FET.

Claim 9

Dependent Claim 29 words

The VCO of claim 7, further comprising an inductance interposed between said gate of said FET and said other one of said anode and said cathode of said varactor.

Claim 10

Dependent Claim 19 words

The VCO of claim 7, wherein said gate of said FET is connected to said anode of said varactor.

Claim 11

Dependent Claim 16 words

The VCO of claim 9, wherein the total length of said gate is approximately 300 microns.

Claim 12

Dependent Claim 41 words

The VCO of claim 1, wherein said source and said drain of said FET define a channel region therebetween within said semiconductor layer, and wherein said gate of said FET forms a Schottky barrier with the respect to said channel region.

Claim 13

Dependent Claim 25 words

The VCO of claim 11, wherein no pathway for DC return exists between said gate and said source or between said gate and said drain.

Claim 14

Dependent Claim 135 words

A monolithic wideband voltage-controlled oscillator (VCO), comprising: an output transistor, said output transistor comprising first, second and third terminals, wherein said transistor amplifies across said second and third terminals a signal provided thereto at said first terminal; a first varactor, said varactor being direct current connected to said first terminal of said transistor; first bias means, connected to said first varactor, for providing a first selected bias voltage thereto; a second varactor, direct current connected to said second terminal of said transistor; second bias means, connected to said second varactor for providing a second selected bias voltage thereto; and first and second RF ground connections, respectively connected to said first and second varactors respectively; said transistor and said varactors being integrated on a common monocrystalline substrate; whereby said third terminal of said transistor sustains oscillation.

Claim 15

Dependent Claim 135 words

A monolithic wideband voltage-controlled oscillator (VCO), comprising: an output transistor, said output transistor comprising first, second and third terminals, wherein said transistor amplifies across said second and third terminals a signal provided thereto at said first terminal; a first varactor, said varactor being direct current connected to said first terminal of said transistor; first bias means, connected to said first varactor, for providing a first selected bias voltage thereto; a second varactor, direct current connected to said second terminal of said transistor; second bias means, connected to said second varactor for providing a second selected bias voltage thereto; and first and second RF ground connections, respectively connected to said first and second varactors respectively; said transistor and said varactors being integrated on a common monocrystalline substrate; whereby said third terminal of said transistor sustains oscillation.

Claim 16

Dependent Claim 84 words

The VCO of claim 13, wherein said first bias means provides said selected voltage to said first varactor for generally matching the frequency of said oscillation at said third terminal of said transistor to a desired frequency; and wherein said second bias means provides said second selected bias voltage to said second varactor for canceling the phase difference of oscillations at said desired frequency between said second terminal of said transistor and RF ground, to precisely match said oscillation frequency to said desired frequency.

Claim 17

Dependent Claim 20 words

The VCO of claim 14, wherein said respective RF ground connections comprise respective capacitors sharing a common layer of metallization.

Claim 18

Dependent Claim 27 words

The VCO of claim 14, wherein no pathway for DC return exists between said first and second nor between said first and third terminals of said transistor.

Claim 19

Dependent Claim 23 words

The VCO of claim 13, 14, 15 or 16, wherein said transistor and said varactors are all formed atop a common semi-insulating substrate.

Claim 20

Dependent Claim 22 words

The VCO of claim 17, wherein said transistor and said respective varactors are all formed within said semiconductor layer atop said substrate.

Claim 21

Dependent Claim 81 words

The VCO of claim 18, wherein each said varactor comprises: an anode and a cathode formed on said semiconductor layer, said anode and cathode being coadjacent and spaced apart from each other, said anode forming a Schottky barrier with said semiconductor layer, the portion of said semiconductor layer beneath said anode being sufficiently thin and sufficiently lightly doped that punch through between said anode and said substrate occurs at a lower voltage than does breakdown between said anode and said cathode.

Claim 22

Dependent Claim 18 words

The VCO of claim 1, wherein said first terminal of said reactor is at least 2 microns wide.

Claim 23

Dependent Claim 29 words

The VCO of claim 1, wherein said first terminal of said reactor is at least 6 times as wide as said semiconducting layer beneath said first terminal is thick.

Claim 24

Dependent Claim 30 words

The VCO of claim 1, wherein all of the periphery of said first terminal of said first varactor is co-adjacent to respective corresponding portions of said second terminal said varactor.

Claim 25

Dependent Claim 25 words

The VCO of claim 1, wherein said semiconducting layer beneath said first terminal of said varactor is continuous with said semiconducting layer beneath said FET.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1987-11-06	1988-05-07	1988-11-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1991-11-06	1992-05-07	1992-11-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1995-11-06	1996-05-07	1996-11-06	$7700.00	Window Closed / Lapsed

Monolithic microwave wide-band VCO

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