US3835418A
Expired / Lapsed
US
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Stabilized alternating current source
Assignee: RFL IND Inc
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Filing: 1972-10-17
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Granted: 1974-09-10
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Expires: 1992-10-17
Abstract
Abstract An extremely stable and accurate d.c. source such as a standard cell is used to control very precisely the magnitude of an a.c. voltage produced by an oscillator. The oscillator output is rectified by means of a full-wave rectifier, and is compared with the voltage of the d.c. standard. Any difference between the standard and the rectified value of the oscillator voltage is integrated by an integrator circuit with a relatively long time constant, and then is used to drive a circuit which controls the ''''Q'''' of the oscillator by negative feedback. This precisely regulates the magnitude of the oscillator output. Preferably, the ''''Q'''' control circuit includes at least one field effect transistor (FET) connected in a bridge network. The FET is used as a voltage-sensitive, relatively distortion-free resistor. In the preferred embodiment of the invention, a ''''biquad'''' oscillator is used to produce three output voltages, the phases of which are separated by 90*. Amplitude of the output voltages is controlled with a high degree of precision by means of the technique described above, except that the ''''Q'''' control circuit uses two FET bridge circuits connected in push-pull.
Inventors
- 👤 R Gilbert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:08
CPC Classifications
H; H03; H03L; H03L5/00
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
138 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, a full-wave rectifier for rectifying the output of said oscillator, said rectifier including a first high-gain amplifier and a unidirectional conduction device connected to the output of said amplifier, a second high-gain amplifier and a second unidirectional conduction device, the latter being connected to the output of said first amplifier, said second amplifier being connected to invert oscillator signals of one polarity, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and a variable impedance device responsive to said error signal for adjusting the magnitude of the output signal from said oscillator in a sense such as to reduce said difference.
Claim 2
Dependent Claim
138 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, a full-wave rectifier for rectifying the output of said oscillator, said rectifier including a first high-gain amplifier and a unidirectional conduction device connected to the output of said amplifier, a second high-gain amplifier and a second unidirectional conduction device, the latter being connected to the output of said first amplifier, said second amplifier being connected to invert oscillator signals of one polarity, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and a variable impedance device responsive to said error signal for adjusting the magnitude of the output signal from said oscillator in a sense such as to reduce said difference.
Claim 3
Dependent Claim
154 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, a rectifier for rectifying the output of said oscillator, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and a variable impedance device responsive to said error signal for adjusting the magnitude of the output signal from said oscillator in a sense such as to reduce said difference, said variable impedance device comprising a field effect transistor (FET) having a gate electrode which is located substantially symmetrically with respect to its channel electrodes, circuit means forming a bridge circuit with the channel resistance of said FET being divided in half and the halves being located in sequential branches, and matching impedances in the other branches, and means for connecting said bridge circuit to receive said error signal.
Claim 4
Dependent Claim
154 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, a rectifier for rectifying the output of said oscillator, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and a variable impedance device responsive to said error signal for adjusting the magnitude of the output signal from said oscillator in a sense such as to reduce said difference, said variable impedance device comprising a field effect transistor (FET) having a gate electrode which is located substantially symmetrically with respect to its channel electrodes, circuit means forming a bridge circuit with the channel resistance of said FET being divided in half and the halves being located in sequential branches, and matching impedances in the other branches, and means for connecting said bridge circuit to receive said error signal.
Claim 5
Dependent Claim
14 words
A source as in claim 2 in which said rectifier is an active rectifier.
Claim 6
Dependent Claim
28 words
A source as in claim 3 in which said rectifier includes a high-gain amplifier and at least one unidirectional conduction device connected to the output of said amplifier.
Claim 7
Dependent Claim
103 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, a full-wave rectifier for rectifying the output of said oscillator, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and a variable impedance device responsive to said error signal for adjusting the magnitude of the output signal from said oscillator in a sense such as to reduce said difference, said variable impedance means including a pair of complementary field-effect transistors (FETs) connected in a push-pull circuit.
Claim 8
Dependent Claim
103 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, a full-wave rectifier for rectifying the output of said oscillator, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and a variable impedance device responsive to said error signal for adjusting the magnitude of the output signal from said oscillator in a sense such as to reduce said difference, said variable impedance means including a pair of complementary field-effect transistors (FETs) connected in a push-pull circuit.
Claim 9
Dependent Claim
71 words
A source as in claim 5 in which each of said FETs has a gate lead which is located substantially symmetrically with respect to its channel electrodes, circuit means forming a bridge circuit with the channel resistance of said FET being divided in half and the halves being located in sequential branches, and matching impedances in the other branches, and means for connecting said bridge circuit to receive said error signal.
Claim 10
Dependent Claim
116 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, said oscillator including means for giving it a substantially infinite Q factor at which its output amplitude is stable, a rectifier for rectifying the output of said oscillator, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and negative feedback means utilizing said error signal for maintaining said Q factor at infinity, said negative feedback means including an active integrator with a relatively long time constant for smoothing said error signal, and a balanced-bridge symmetrical FET variable impedance circuit.
Claim 11
Dependent Claim
116 words
A stabilized alternating current source comprising, in combination, a stable d-c reference source, an electrical oscillator, said oscillator including means for giving it a substantially infinite Q factor at which its output amplitude is stable, a rectifier for rectifying the output of said oscillator, means for comparing the rectified output voltage of said rectifier with the voltage of said d-c reference source and creating an error signal corresponding to the difference between said voltages, and negative feedback means utilizing said error signal for maintaining said Q factor at infinity, said negative feedback means including an active integrator with a relatively long time constant for smoothing said error signal, and a balanced-bridge symmetrical FET variable impedance circuit.
Claim 12
Dependent Claim
31 words
A source as in claim 7 in which said oscillator is a Wien bridge oscillator and said variable impedance circuit is connected in one arm of the bridge of said oscillator.
Claim 13
Dependent Claim
14 words
A source as in claim 7 in which said oscillator is a biquad oscillator.
Claim 14
Dependent Claim
15 words
A source as in claim 7 in which said rectifier is a full-wave active rectifier.
Claim 15
Dependent Claim
22 words
A source as in claim 7 including a second FET circuit, said FET circuits having complementary FETs connected in a push-pull configuration.
Claim 16
Dependent Claim
91 words
A stable multiphase-output source comprising, in combination, a biquad oscillator providing output voltages separated in phase by 90* to 180*, an active rectifier connected to receive one of said output voltages, a stable d.c. reference source, means for comparing the output of said rectifier with that of said d.c. source and producing a difference signal, an active integrator for smoothing said difference signal, a push-pull FET circuit controlling the amplitude-determining impedance of said oscillator in accordance with the smoothed difference signal in a sense such as to reduce said difference signal.
Claim 17
Dependent Claim
91 words
A stable multiphase-output source comprising, in combination, a biquad oscillator providing output voltages separated in phase by 90* to 180*, an active rectifier connected to receive one of said output voltages, a stable d.c. reference source, means for comparing the output of said rectifier with that of said d.c. source and producing a difference signal, an active integrator for smoothing said difference signal, a push-pull FET circuit controlling the amplitude-determining impedance of said oscillator in accordance with the smoothed difference signal in a sense such as to reduce said difference signal.
Claim 18
Dependent Claim
25 words
A source as in claim 12 in which oscillator voltages separated by 180* in phase from one another are used to energize said push-pull circuit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-09 | 1978-03-11 | 1978-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-09 | 1982-03-11 | 1982-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-09 | 1986-03-11 | 1986-09-10 | $7700.00 | Window Closed / Lapsed |