US3718864A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Crossover detector
Assignee: Cogar Corp
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Filing: 1971-02-26
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Granted: 1973-02-27
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Expires: 1991-02-26
Abstract
Abstract A crossover detector utilizing an operational amplifier, a first input of which is connected through a resistor to ground and the second input of which is connected to the signal source. The output is fed back through an RC circuit to the first input. The time constant of the RC circuit is such that the prior art hysteresis time-delay error is eliminated because a hysteresis effect is introduced only immediately after a crossover is detected; the hysteresis effect decays exponentially and is essentially totally absent by the time that the next crossover occurs.
Inventors
- 👤 W Kelly
- 👤 W Reynolds
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:57
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/153; H03K5/1536
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
134 words
A crossover detector comprising an operational amplifier having first and second input terminals and an output terminal, means for applying an input signal to said first input terminal, means for extending a reference potential to said second input terminal, said reference potential being equal to the threshold level at which crossovers in said input signal are to be detected, said operational amplifier being operative to apply one of two potentials at its output terminal in accordance with the relative polarities of the potentials at said first and second input terminals, and means responsive immediately after a crossover occurs above or below said reference potential for introducing a hysteresis effect in the operation of said operational amplifier and for allowing said hysteresis effect to decay prior to the next expected crossover in said input signal.
Claim 2
Dependent Claim
134 words
A crossover detector comprising an operational amplifier having first and second input terminals and an output terminal, means for applying an input signal to said first input terminal, means for extending a reference potential to said second input terminal, said reference potential being equal to the threshold level at which crossovers in said input signal are to be detected, said operational amplifier being operative to apply one of two potentials at its output terminal in accordance with the relative polarities of the potentials at said first and second input terminals, and means responsive immediately after a crossover occurs above or below said reference potential for introducing a hysteresis effect in the operation of said operational amplifier and for allowing said hysteresis effect to decay prior to the next expected crossover in said input signal.
Claim 3
Dependent Claim
45 words
A crossover detector in accordance with claim 1 wherein said last-mentioned means controls a step change in the potential applied to said second input terminal and thereafter controls said potential to decay exponentially with the decay being substantially complete prior to the next expected crossover.
Claim 4
Dependent Claim
27 words
A crossover detector in accordance with claim 1 wherein said last-mentioned means is a capacitive feedback circuit connected between said output terminal and said second input terminal.
Claim 5
Dependent Claim
24 words
A crossover detector in accordance with claim 3 wherein said capacitive feedback circuit includes resistor means connected between said second input terminal and ground.
Claim 6
Dependent Claim
34 words
A crossover detector in accordance with claim 4 wherein said capacitive feedback circuit includes additional resistor means connected in series with said capacitive feedback circuit between said output terminal and said second input terminal.
Claim 7
Dependent Claim
88 words
A crossover detector in accordance with claim 3 wherein said capacitive feedback circuit having a time constant that is substantially less than the anticipated time interval between successive crossovers to be detected, said operational amplifier having a negative output signal when the signal at said first input terminal is positive relative to the signal at said second input terminal as compared with the output signal of said operational amplifier when the signal at said second input terminal is pOsitive relative to the signal at said first input terminal.
Claim 8
Dependent Claim
62 words
A crossover detector in accordance with claim 1 wherein said means responsive immediately after a crossover occurs being responsive to a change in said output potential for changing the potential applied to said second input terminal and for allowing the potential at said second input terminal to return to said reference potential prior to the next expected crossover in said input signal.
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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) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |