US3796962A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase lock loop and frequency discriminator employed therein
Assignee: Hekimian Laboratories Inc
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Filing: 1972-10-06
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Granted: 1974-03-12
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Expires: 1992-10-06
Abstract
Abstract A phase lock loop employs a frequency discriminator having a relatively slow response to pull a voltage controlled oscillator into frequency lock with an input signal. After frequency lock the output of the frequency discriminator is nulled and a phase detector becomes effective to maintain phase lock. The frequency discriminator utilizes an operational amplifier to which both the input and oscillator signals are capacitively coupled through respective oppositely poled diode gates. A feedback capacitor, which is much larger than the input coupling capacitors, has charge transferred thereto from each coupling capacitor during alternate half cycles of the input and oscillator signals. The net charge across the feedback capacitor is a measure of the frequency difference between the input and oscillator signals, and is zero at frequency lock.
Inventors
- 👤 N Hekimian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:01
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/10; H03L7/113; Y; Y10; Y10S; Y10S331/00; Y10S331/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
282 words
A frequency discriminator circuit for receiving first and second input signals having frequencies which vary relative to one another, and providing an output signal having an amplitude which varies in proportion to the difference between the frequencies of said input signals, said circuit consisting of: an operational amplifier of the type having an input terminal which is held at virtual ground during operation, and an output terminal which provides a signal of opposite polarity to the signal applied to said input terminal, said output terminal being connected to provide said output signal for said circuit; a storage capacitor of relatively large capacitance connected between said input and output terminals; first and second coupling capacitors, each having first and second terminals and having substantially less capacitance than said storage capacitor; means for applying said first input signal to said first terminal of said first coupling capacitor; a first gating circuit including: a first diode having a cathode connected directly to said second terminal of said first coupling capacitor and an anode connected directly to circuit ground; and a second diode having an anode connected directly to the cathode of said first diode and having a cathode connected directly to the input terminal of said operational amplifier; means for applying said second input signal to said first terminal of said second coupling capacitor; and a second gating circuit including: a third diode having an anode connected directly to said second terminal of said second coupling capacitor and a cathode connected directly to circuit ground; and a fourth diode having a cathode connected directly to the anode of said third diode and having an anode connected directly to said input terminal of said operational amplifier.
Claim 2
Dependent Claim
282 words
A frequency discriminator circuit for receiving first and second input signals having frequencies which vary relative to one another, and providing an output signal having an amplitude which varies in proportion to the difference between the frequencies of said input signals, said circuit consisting of: an operational amplifier of the type having an input terminal which is held at virtual ground during operation, and an output terminal which provides a signal of opposite polarity to the signal applied to said input terminal, said output terminal being connected to provide said output signal for said circuit; a storage capacitor of relatively large capacitance connected between said input and output terminals; first and second coupling capacitors, each having first and second terminals and having substantially less capacitance than said storage capacitor; means for applying said first input signal to said first terminal of said first coupling capacitor; a first gating circuit including: a first diode having a cathode connected directly to said second terminal of said first coupling capacitor and an anode connected directly to circuit ground; and a second diode having an anode connected directly to the cathode of said first diode and having a cathode connected directly to the input terminal of said operational amplifier; means for applying said second input signal to said first terminal of said second coupling capacitor; and a second gating circuit including: a third diode having an anode connected directly to said second terminal of said second coupling capacitor and a cathode connected directly to circuit ground; and a fourth diode having a cathode connected directly to the anode of said third diode and having an anode connected directly to said input terminal of said operational amplifier.
Claim 3
Dependent Claim
36 words
The frequency discriminator circuit according to claim 1 wherein said input terminal of said operational amplifier is an inverting input terminal, and wherein said operational amplifier additionally includes a non-inverting input terminal connected to circuit ground.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |