US3784845A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linear frequency to voltage converter circuit
Assignee: Honeywell Inc
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Filing: 1973-02-06
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Granted: 1974-01-08
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Expires: 1993-02-06
Abstract
Abstract A device which includes a squaring amplifier responsive to an applied input frequency signal for producing constant amplitude square waves at the same frequency as the applied input signal. A switch coupled to the amplifier enables a capacitor to be rapidly charged from a reference voltage and a voltage due to an accumulated charge on a second capacitor during the first half cycle of each square wave. The charge accumulated on the first capacitor is rapidly transferred to the second capacitor during the second half cycle of each square wave through a second switch. The voltage due to the accumulated charge on the second capacitor is coupled through a long time constant discharge circuit to a buffer amplifier including a feedback ripple filter whereby the amplifier provides an output D.C. voltage which is linearly proportional to the frequency of the input signal.
Inventors
- 👤 G Haas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:29
CPC Classifications
H; H03; H03K; H03K9/00; H03K9/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
223 words
A converter circuit for providing an output D.C. voltage which is linearly proportional to the frequency of an applied input signal comprising an amplifier responsive to said applied input signal for providing square waves of constant amplitude at the same frequency as said applied input signal, first switching means coupled to said amplifier and responsive to said square waves, a source of reference potential, first capacitor means coupled to said reference potential and said first switching means whereby said first switching means alternately couples a terminal of said capacitor means between said reference potential and ground potential during successive half cycles of each square wave, second and third switching means synchronously operable with said first switching means and coupled to said amplifier and said first capacitor means, second capacitor means coupled to said second and third switching means whereby said second capacitor means alternately applies an accumulated potential through said third switching means To said first capacitor means and receives a constant value of differential charge from said first capacitor means through said second switching means during successive half cycles respectively of each square wave, and resistor means coupled to said second capacitor means forming a long time constant discharging circuit for providing an output D.C. voltage having an average value which is linearly proportional to said frequency of said applied input signal.
Claim 2
Dependent Claim
223 words
A converter circuit for providing an output D.C. voltage which is linearly proportional to the frequency of an applied input signal comprising an amplifier responsive to said applied input signal for providing square waves of constant amplitude at the same frequency as said applied input signal, first switching means coupled to said amplifier and responsive to said square waves, a source of reference potential, first capacitor means coupled to said reference potential and said first switching means whereby said first switching means alternately couples a terminal of said capacitor means between said reference potential and ground potential during successive half cycles of each square wave, second and third switching means synchronously operable with said first switching means and coupled to said amplifier and said first capacitor means, second capacitor means coupled to said second and third switching means whereby said second capacitor means alternately applies an accumulated potential through said third switching means To said first capacitor means and receives a constant value of differential charge from said first capacitor means through said second switching means during successive half cycles respectively of each square wave, and resistor means coupled to said second capacitor means forming a long time constant discharging circuit for providing an output D.C. voltage having an average value which is linearly proportional to said frequency of said applied input signal.
Claim 3
Dependent Claim
41 words
A converter circuit as recited in claim 1 which further includes a buffer amplifier and cascaded filter coupled to said resistor means for reducing ripple in said output D.C. voltage due to said charging and discharging of said second capacitor means.
Claim 4
Dependent Claim
52 words
A converter circuit as recited in claim 2 which further includes a variable resistance circuit coupled between said source of reference potential and said resistor means for providing an adjustable output D.C. voltage which may be set to a desired reference level corresponding to a selected frequency of said applied input signal.
Claim 5
Dependent Claim
36 words
A converter circuit as recited in claim 1 in which said first switching means includes a solid state switch having a short switching time, a low value of resistance during conduction and a low off-set voltage.
Claim 6
Dependent Claim
65 words
A converter circuit as recited in claim 1 in which said first capacitor means includes a capacitor having a minimal value of temperature co-efficient and a very high insulation resistance whereby said capacitor maintains a substantially constant value of capacity and a minimal amount of leakage thereby enabling said first capacitor means to transfer a constant value of differential charge to said second capacitor means.
Claim 7
Dependent Claim
59 words
A converter circuit as recited in claim 1 in which said third switching means includes a solid state switch having a very short switching time and a low value of resistance during conduction which forms a short time constant charging circuit into said first capacitor means for charges produced by said accumulated potential applied from said second capacitor means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |