US3703686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase lock loop and frequency discriminator employed therein
Assignee: Hekimian Laboratories Inc
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Filing: 1971-09-17
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Granted: 1972-11-21
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Expires: 1991-09-17
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 fro m each coupling capacitors 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
- 👤 Norris C Hekimian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:54
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/10; H03L7/113
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
291 words
A circuit for generating an output signal having a constant phase relationship with an input signal, said input signal being of the type which exhibits both frequency and phase variations, said circuit comprising: voltage controlled oscillator means for providing said output signal at a frequency which is a predetermined function of the amplitude of a control signal applied thereto; phase detector means for providing a first signal at an amplitude which varies as a function of the phase difference between said input signal and said output signal; a frequency discriminator for receiving said input signal and said output signal and for providing a second signal at an amplitude which varies iN proportion to the frequency difference between said input and output signals, said frequency discriminator comprising: a storage capacitor, first and second coupling capacitors for receiving said input and output signals respectively, first gating means connected between said first coupling capacitor and said storage capacitor for providing a charging path for said first coupling capacitor during half cycles of one polarity of said input signal and for providing a transfer path for transferring charge from said first coupling capacitor to said storage capacitor during half cycles of a second polarity of said input signal, and second gating means connected between said second coupling capacitor and said storage capacitor for providing a charging path for said second coupling capacitor during half cycles of said second polarity of said output signal and for providing a transfer path for transferring charge from said second coupling capacitor to said storage capacitor during half cycles of said one polarity of said output signal; and means for summing said first and second signals to provide said control signal for controlling the frequency of said voltage controlled oscillator.
Claim 2
Dependent Claim
291 words
A circuit for generating an output signal having a constant phase relationship with an input signal, said input signal being of the type which exhibits both frequency and phase variations, said circuit comprising: voltage controlled oscillator means for providing said output signal at a frequency which is a predetermined function of the amplitude of a control signal applied thereto; phase detector means for providing a first signal at an amplitude which varies as a function of the phase difference between said input signal and said output signal; a frequency discriminator for receiving said input signal and said output signal and for providing a second signal at an amplitude which varies iN proportion to the frequency difference between said input and output signals, said frequency discriminator comprising: a storage capacitor, first and second coupling capacitors for receiving said input and output signals respectively, first gating means connected between said first coupling capacitor and said storage capacitor for providing a charging path for said first coupling capacitor during half cycles of one polarity of said input signal and for providing a transfer path for transferring charge from said first coupling capacitor to said storage capacitor during half cycles of a second polarity of said input signal, and second gating means connected between said second coupling capacitor and said storage capacitor for providing a charging path for said second coupling capacitor during half cycles of said second polarity of said output signal and for providing a transfer path for transferring charge from said second coupling capacitor to said storage capacitor during half cycles of said one polarity of said output signal; and means for summing said first and second signals to provide said control signal for controlling the frequency of said voltage controlled oscillator.
Claim 3
Dependent Claim
291 words
A circuit for generating an output signal having a constant phase relationship with an input signal, said input signal being of the type which exhibits both frequency and phase variations, said circuit comprising: voltage controlled oscillator means for providing said output signal at a frequency which is a predetermined function of the amplitude of a control signal applied thereto; phase detector means for providing a first signal at an amplitude which varies as a function of the phase difference between said input signal and said output signal; a frequency discriminator for receiving said input signal and said output signal and for providing a second signal at an amplitude which varies iN proportion to the frequency difference between said input and output signals, said frequency discriminator comprising: a storage capacitor, first and second coupling capacitors for receiving said input and output signals respectively, first gating means connected between said first coupling capacitor and said storage capacitor for providing a charging path for said first coupling capacitor during half cycles of one polarity of said input signal and for providing a transfer path for transferring charge from said first coupling capacitor to said storage capacitor during half cycles of a second polarity of said input signal, and second gating means connected between said second coupling capacitor and said storage capacitor for providing a charging path for said second coupling capacitor during half cycles of said second polarity of said output signal and for providing a transfer path for transferring charge from said second coupling capacitor to said storage capacitor during half cycles of said one polarity of said output signal; and means for summing said first and second signals to provide said control signal for controlling the frequency of said voltage controlled oscillator.
Claim 4
Dependent Claim
291 words
A circuit for generating an output signal having a constant phase relationship with an input signal, said input signal being of the type which exhibits both frequency and phase variations, said circuit comprising: voltage controlled oscillator means for providing said output signal at a frequency which is a predetermined function of the amplitude of a control signal applied thereto; phase detector means for providing a first signal at an amplitude which varies as a function of the phase difference between said input signal and said output signal; a frequency discriminator for receiving said input signal and said output signal and for providing a second signal at an amplitude which varies iN proportion to the frequency difference between said input and output signals, said frequency discriminator comprising: a storage capacitor, first and second coupling capacitors for receiving said input and output signals respectively, first gating means connected between said first coupling capacitor and said storage capacitor for providing a charging path for said first coupling capacitor during half cycles of one polarity of said input signal and for providing a transfer path for transferring charge from said first coupling capacitor to said storage capacitor during half cycles of a second polarity of said input signal, and second gating means connected between said second coupling capacitor and said storage capacitor for providing a charging path for said second coupling capacitor during half cycles of said second polarity of said output signal and for providing a transfer path for transferring charge from said second coupling capacitor to said storage capacitor during half cycles of said one polarity of said output signal; and means for summing said first and second signals to provide said control signal for controlling the frequency of said voltage controlled oscillator.
Claim 5
Dependent Claim
27 words
The circuit according to claim 1 wherein the capacitance of said storage capacitor is at least five times the capacitance of said first and second coupling capacitors.
Claim 6
Dependent Claim
70 words
The circuit according to claim 2 wherein said frequency discriminator further comprises an operational amplifier having an input terminal and an output terminal, wherein said storage capacitor is connected between said output terminal and said input terminal, wherein said first gating means is connected between said first coupling capacitor and said input terminal, and wherein said second gating means is connected between said second coupling capacitor and said input terminal.
Claim 7
Dependent Claim
46 words
The circuit according to claim 3 further comprising a resistor connected in parallel with said storage capacitor, the time constant provided by said resistor and said storage capacitor being large relative to the period of said input signal over the frequency range of said input signal.
Claim 8
Dependent Claim
169 words
The circuit according to claim 3: wherein said first gating means includes a first diode connected between said first coupling capacitor and ground to permit said input signal to charge said first coupling capacitor during said one polarity of said input signal, and a second diode connected between said first coupling capacitor and said input terminal of said operational amplifier to permit charge transfer from said first coupling capacitor to said storage capacitor during half cycles of said second polarity of said input signal; and wherein said second gating means includes a third diode connected between said second coupling capacitor and ground to provide a charging path for said second coupling capacitor during half cycles of said second polarity of said output signal, and a fourth diode connected between said second coupling capacitor and said input terminal of said operational amplifier for providing a path for transferring charge from said second coupling capacitor to said storage capacitor during half cycles of said one polarity of said one output signal.
Claim 9
Dependent Claim
192 words
The circuit according to claim 1 wherein said voltage controlled oscillator includes: an integrator comprising an operational amplifier having an inverting input terminal and an output terminal, and a feedback capacitor connected between said inverting input terminal and said output terminal; a Schmitt trigger comprising an operational amplifier and means for biasing said last mentioned operational amplifier to provide a Schmitt trigger output signal at one polarity when the output signal from said integrator is below a predetermined level and for providing a Schmitt trigger output signal at a second polarity when the output signal from said integrator is above said predetermined level; feedback means for coupling the Schmitt trigger output signal to the iNput terminal of said integrator, said feedback means including a first feedback path which is operative to connect said Schmitt trigger output signal of one polarity to the input terminal of said integrator but is inoperative to connect said Schmitt trigger output signal of a second polarity to the input terminal of said integrator, and a second feedback path operative to couple said Schmitt trigger output signal of said second polarity to said input terminal of said integrator.
Claim 10
Dependent Claim
48 words
The circuit according to claim 6 wherein said first feedback path includes a diode in series with a first resistor of relatively low resistance, and wherein said second feedback path includes a second resistor of relatively high resistance, said first and second feedback paths being connected in parallel.
Claim 11
Dependent Claim
23 words
The circuit according to claim 1 wherein said phase detector comprises: an exclusive OR gate which receives both said input and output signals.
Claim 12
Dependent Claim
85 words
The circuit according to claim 8 wherein said exclusive OR gate comprises an operational amplifier having a non-inverting input terminal, an inverting input terminal, and an output terminal; a first diode having its cathode connected to said non-inverting input terminal; a second diode having its anode connected to said inverting input terminal; a common junction; means coupling the anode of said first diode and cathode of said second diode to said common junction; and means coupling said input and output signals to said common junction.
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) | 1975-11-21 | 1976-05-22 | 1976-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-21 | 1980-05-22 | 1980-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-21 | 1984-05-22 | 1984-11-21 | $7700.00 | Window Closed / Lapsed |