Patent US3829797A successfully refreshed from Google Patents.
US3829797A
Expired / Lapsed
US
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Modulator and method
Assignee: KARKAR ELECTRONICS Inc
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Filing: 1973-07-23
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Granted: 1974-08-13
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Expires: 1993-07-23
Abstract
Abstract An amplitude modulator using an FET, or MOSFET and a coupling and phase splitting device capable of accepting both single ended and balanced inputs (like for example, a differential amplifier or a center tapped choke coil, or a transformer). The source and drain terminals are connected to the differential inputs (outputs) of the device, and the signal to the single ended input of the device. The carrier is applied to the gate terminal of the FET or MOSFET. The switching action of the device is equally efficient for both single ended and differential inputs (outputs). However, the carrier leak voltage is being applied simultaneously to both terminals of the differential input and thus suppressed in the output by virtue of high suppression of longitudinal (common) mode pertinent to devices with differential inputs (outputs). Other modulators are disclosed including a double balanced modulator using two complimentary field effect transistors and a double balanced modulator using two field effect transistors of the same conductivity type.
Inventors
- 👤 E Karkar
- 👤 N Kovalevski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:33
CPC Classifications
H; H03; H03C; H03C1/00; H03C1/36; H03C1/52; H03C1/54; H03C1/542; H03C1/547; H03C2200/00; H03C2200/0037; H03C2200/0066
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
263 words
A double balanced amplitude modulator for changing the amplitude of a carrier wave in accordance with a signal wave to form a modulated wave comprising a pair of field effect transistors each having source drain and gate electrodes and each having inherent parasitic capacitances between their gate and source electrodes and gate and drain electrodes, respectively, means for applying a carrier wave to said gates of said field effect transistors, a pair of input terminals adapted to be connected to a signal wave source, coupling means for coupling the signal wave at the pair of input terminals across the source and drain electrodes of both said field effect transistors, said coupling means comprising a transformer having a primary winding and a pair of secondary windings, said primary winding connected to said input terminals, one of said secondary windings connected across the source and drain electrodes of one of said field effect transistors and the other of said secondary windings connected across the source and drain electrodes of the other of said field effect transistors, both of said secondary windings having center taps, a pair of output terminals, means connecting the center tap of one of said secondary windings to one of said output terminals and means connecting the center tap of the other of said secondary windings to the other of said output terminals whereby carrier leaks due to parasitic capacitances between the source and gate and the drain and gate electrodes of each of said field effect transistors cancel each other at the respective center taps of said pair of secondary windings.
Claim 2
Dependent Claim
263 words
A double balanced amplitude modulator for changing the amplitude of a carrier wave in accordance with a signal wave to form a modulated wave comprising a pair of field effect transistors each having source drain and gate electrodes and each having inherent parasitic capacitances between their gate and source electrodes and gate and drain electrodes, respectively, means for applying a carrier wave to said gates of said field effect transistors, a pair of input terminals adapted to be connected to a signal wave source, coupling means for coupling the signal wave at the pair of input terminals across the source and drain electrodes of both said field effect transistors, said coupling means comprising a transformer having a primary winding and a pair of secondary windings, said primary winding connected to said input terminals, one of said secondary windings connected across the source and drain electrodes of one of said field effect transistors and the other of said secondary windings connected across the source and drain electrodes of the other of said field effect transistors, both of said secondary windings having center taps, a pair of output terminals, means connecting the center tap of one of said secondary windings to one of said output terminals and means connecting the center tap of the other of said secondary windings to the other of said output terminals whereby carrier leaks due to parasitic capacitances between the source and gate and the drain and gate electrodes of each of said field effect transistors cancel each other at the respective center taps of said pair of secondary windings.
Claim 3
Dependent Claim
61 words
An amplitude modulator in accordance with claim 1 wherein said pair of field effect transistors are of the same conductivity type and wherein the carrier wave applied to the gate of one of said field effect transistors is shifted 180* in phase with respect to the carrier wave applied to the gate electrode of the other of said field effect transistors.
Claim 4
Dependent Claim
17 words
An amplitude modulator in accordance with claim 1 wherein said pair of field effect transistors are complementary.
Claim 5
Dependent Claim
41 words
An amplitude modulator in accordance with claim 1 which is reversible whereby the signal wave can be applied to either the input or the output terminals which results in the modulated wave appearing at either the output or input terminals, respectively.
Claim 6
Dependent Claim
99 words
An amplitude modulator in accordance with claim 1 wherein the carrier wave is a square wave and wherein said pair of field effect transistors each require a finite time for switching in response to the square carrier wave so that even harmonics of the fundamental frequency of the carrier wave are produced and Wherein said even harmonics appear at both the source and drain electrodes of both of said pair of field effect transistors, and wherein said center taps cause half of the even harmonics to be phase shifted to cancel out the other half of the even harmonics.
References Cited (Backward Citations)
US3281718A
Cited
US3397353A
Cited
US3383601A
Cited
US3577206A
Cited
US3646364A
Cited
US3668561A
Cited
US3727078A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |