US3737897A
Expired / Lapsed
US
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Analog to digital converter
Assignee: International Standard Electric Corp
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Filing: 1971-12-29
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Granted: 1973-06-05
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Expires: 1991-12-29
Abstract
Abstract An analog to digital converter is disclosed having a reference signal in the form of a ramp waveform starting at a given negative potential and increasing to a given positive potential through ground or zero potential. Two amplitude comparators are provided, the first comparator producing a first output signal when the amplitude of the analog signal equals the amplitude of the ramp waveform and the second comparator producing a second output signal when the amplitude of the ramp waveform equals zero or ground potential. A counting and arithmetic arrangement responds to the first and second output signals to provide a digital output signal representative of the amplitude difference between ground potential and the amplitude of the analog signal. A polarity detector is coupled to the output of the first and second detectors and in response to the first and second output signals provide a digital bit representing the polarity of the analog signal. A storage device combines the digital output signal from the counting and arithmetic arrangement and the digital bit from the polarity detector to provide the digital output signal for the converter. Three embodiments of the counting and arithmetic arrangement are disclosed.
Inventors
- 👤 L Cuthbert
- 👤 R Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:39
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/50
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
328 words
An analog to digital converter comprising: a first source of reference signal in the form of a ramp waveform starting at a given negative potential and increasing to a given positive potential through ground potential; a second source of input analog signal; a first amplitude comparator coupled to said first and second sources providing a first output signal when the amplitude of said analog signal and the amplitude of said reference signal are equal; a second amplitude comparator coupled to said first source and said ground potential providing a second output signal when the amplitude of said reference signal equals said ground potential; first means coupled to said first and second comparators responsive to said first and second output signals to provide a first digital output signal representative of the amplitude difference between said ground potential and the amplitude of said analog signal; second means coupled to said first and second comparators responsive to said first and second output signalS to provide a second digital output signal indicating the polarity of said analog signal; and third means coupled to said first and second means to combine said first and second digital output signals and thereby provide a digital output signal for said converter; said first means including digital counting means; said counting means including a first digital counter coupled to said first comparator, the counting of said first counter being stated at the start of said ramp waveform and stopped in response to said first output signal, a second digital counter coupled to said second comparator, the counting of said second counter being started at the start of said ramp waveform and stopped in response to said second output signal, and fourth means coupled to said first and second counters to subtract the count of the first of said first and second counters to stop counting from the count of the second of said first and second counters to stop counting to produce said first digital output signal.
Claim 2
Dependent Claim
328 words
An analog to digital converter comprising: a first source of reference signal in the form of a ramp waveform starting at a given negative potential and increasing to a given positive potential through ground potential; a second source of input analog signal; a first amplitude comparator coupled to said first and second sources providing a first output signal when the amplitude of said analog signal and the amplitude of said reference signal are equal; a second amplitude comparator coupled to said first source and said ground potential providing a second output signal when the amplitude of said reference signal equals said ground potential; first means coupled to said first and second comparators responsive to said first and second output signals to provide a first digital output signal representative of the amplitude difference between said ground potential and the amplitude of said analog signal; second means coupled to said first and second comparators responsive to said first and second output signalS to provide a second digital output signal indicating the polarity of said analog signal; and third means coupled to said first and second means to combine said first and second digital output signals and thereby provide a digital output signal for said converter; said first means including digital counting means; said counting means including a first digital counter coupled to said first comparator, the counting of said first counter being stated at the start of said ramp waveform and stopped in response to said first output signal, a second digital counter coupled to said second comparator, the counting of said second counter being started at the start of said ramp waveform and stopped in response to said second output signal, and fourth means coupled to said first and second counters to subtract the count of the first of said first and second counters to stop counting from the count of the second of said first and second counters to stop counting to produce said first digital output signal.
Claim 3
Dependent Claim
85 words
A converter according to claim 1, wherein said fourth means includes a digital complementer coupled to said first of said first and second counters to stop counting, and a digital adder coupled to said complementer and said second of said first and second counters to stop counting, said adder adding the complemented count at the output of said complementer to the true count at the output of said second of said first and second counters to stop counting to produce said first digital output signal.
Claim 4
Dependent Claim
353 words
An analog to digital converter comprising: a first source of reference signal in the form of a ramp waveform starting at a given negative potential and increasing to a given positive potential through ground potential; a second source of input analog signal; a first amplitude comparator coupled to said first and second sources providing a first output signal when the amplitude of said analog signal and the amplitude of said reference signal are equal; a second amplitude comparator coupled to said first source and said ground potential providing a second output signal when the amplitude of said reference signal equals said ground potential; first means coupled to said first and second comparators responsive to said first and second output signals to provide a first digital output signal representative of the amplitude difference between said ground potential and the amplitude of said analog signal; second means coupled to said first and second comparators responsive to said first and second output signals to provide a second digital output signal indicating the polarity of said analog signal; and third means coupled to said first and second means to combine said first and second digital output signals and thereby provide a digital output signal for said converter; said first means including digital counting means; said counting means including third means coupled to said first and second comparators responsive to the first of said first and second input signals produced to produce a third output signal and to the second of said first and second output signals produced to produce a fourth output signal, a first digital counter coupled to said third means, the counting of said first counter being started at the start of said ramp waveform and stopped in response to said third output signal, a digital complementer coupled to said first counter, a second digital counter coupled to said third means, the counting of said second counter being started at the start of said ramp waveform and stopped in response to said fourth output signal; and a digital adder coupled to said complementer and said second digital counter to produce said first digital output signal.
Claim 5
Dependent Claim
353 words
An analog to digital converter comprising: a first source of reference signal in the form of a ramp waveform starting at a given negative potential and increasing to a given positive potential through ground potential; a second source of input analog signal; a first amplitude comparator coupled to said first and second sources providing a first output signal when the amplitude of said analog signal and the amplitude of said reference signal are equal; a second amplitude comparator coupled to said first source and said ground potential providing a second output signal when the amplitude of said reference signal equals said ground potential; first means coupled to said first and second comparators responsive to said first and second output signals to provide a first digital output signal representative of the amplitude difference between said ground potential and the amplitude of said analog signal; second means coupled to said first and second comparators responsive to said first and second output signals to provide a second digital output signal indicating the polarity of said analog signal; and third means coupled to said first and second means to combine said first and second digital output signals and thereby provide a digital output signal for said converter; said first means including digital counting means; said counting means including third means coupled to said first and second comparators responsive to the first of said first and second input signals produced to produce a third output signal and to the second of said first and second output signals produced to produce a fourth output signal, a first digital counter coupled to said third means, the counting of said first counter being started at the start of said ramp waveform and stopped in response to said third output signal, a digital complementer coupled to said first counter, a second digital counter coupled to said third means, the counting of said second counter being started at the start of said ramp waveform and stopped in response to said fourth output signal; and a digital adder coupled to said complementer and said second digital counter to produce said first digital output signal.
Claim 6
Dependent Claim
57 words
A converter according to claim 3,wherein said third means includes a plurality of bistable stages coupled to said adder and said second means, the number of said stages being equal to the number of digitaL bits of the counts being added together in said adder plus the number of digital bits of said second digital output signal.
Claim 7
Dependent Claim
20 words
A converter according to claim 4, wherein the number of digital bits of said second digital output signal equals one.
References Cited (Backward Citations)
US3111662A
Cited
US3505668A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |