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US3633202A
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Self-calibrating analog-to-digital converter
Assignee: International Business Machines Corp
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Filing: 1969-12-31
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Granted: 1972-01-04
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Expires: 1989-12-31
Abstract
Abstract The method and apparatus for providing a self-calibrating ADC of the type which utilizes a voltage controlled oscillator in conjunction with a counting register to translate an analog signal into time domain. A second counting register, a fixed frequency pulse source, and zero and full scale reference voltages are used to generate span and zero calibration factors to any desired accuracy.
Inventors
- 👤 Paul A Kuckein
- 👤 Francis E Mueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:47
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/10; H03M1/1009
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
164 words
The method of generAting a span calibration factor for a self-calibrating analog-to-digital converter utilizing first and second counting means comprising the steps of: setting a stored calibration count in the second counting means; counting pulses in the first counting means in a first direction at a variable rate determined by a first voltage source for a predetermined time; counting pulses in said first counting means in the opposite direction at a variable rate determined by a second voltage source until said first counting means reaches a predetermined count while simultaneously counting a second counting means at a fixed rate; comparing the count in said second counting means with the stored calibration count; repeating the above steps on the occurrence of a noncompare indication after replacing the stored calibration count with the count in said second counting means; and storing the count in the second counting means on the occurrence of a compare signal as the span calibration factor for use in subsequent conversion operations.
Claim 2
Independent Claim
164 words
The method of generAting a span calibration factor for a self-calibrating analog-to-digital converter utilizing first and second counting means comprising the steps of: setting a stored calibration count in the second counting means; counting pulses in the first counting means in a first direction at a variable rate determined by a first voltage source for a predetermined time; counting pulses in said first counting means in the opposite direction at a variable rate determined by a second voltage source until said first counting means reaches a predetermined count while simultaneously counting a second counting means at a fixed rate; comparing the count in said second counting means with the stored calibration count; repeating the above steps on the occurrence of a noncompare indication after replacing the stored calibration count with the count in said second counting means; and storing the count in the second counting means on the occurrence of a compare signal as the span calibration factor for use in subsequent conversion operations.
Claim 3
Dependent Claim
101 words
The method of generating a zero calibration factor in a self-calibrating analog-to-digital converter utilizing first and second counting means according to claim 1 comprising the additional steps of: storing the span calibration factor in said second counting means; and counting said first counting means in a first direction from a reference count at a variable rate determined by a first voltage source and simultaneously counting to said reference count in said second counting means the pulses produced by fixed rate pulses to produce the zero calibration factor in said first counting means when said second counting means reaches said reference count.
Claim 4
Dependent Claim
160 words
A self-calibrating analog-to-digital converter comprising: first and second digital counting means; pulse-producing means for producing a series of output pulses having a variable repetition rate dependent upon the amplitude of the input signal; means for producing pulses having a fixed repetition rate; a first and a second reference voltage source, means responsive to said first and second reference voltage sources for generating a span calibration factor in said second counting means; means responsive to said span calibration factor and said first reference voltage source for generating a zero calibration factor in said first counting means; means for connecting an analog signal of unknown magnitude to said pulse-producing means; and means for connecting the pulses from said pulse-producing means to count said first counting means for the time required for said fixed rate pulses to count said second counting means to a reference count whereby the count then in said first counting means is the digital representation of said analog signal.
Claim 5
Dependent Claim
160 words
A self-calibrating analog-to-digital converter comprising: first and second digital counting means; pulse-producing means for producing a series of output pulses having a variable repetition rate dependent upon the amplitude of the input signal; means for producing pulses having a fixed repetition rate; a first and a second reference voltage source, means responsive to said first and second reference voltage sources for generating a span calibration factor in said second counting means; means responsive to said span calibration factor and said first reference voltage source for generating a zero calibration factor in said first counting means; means for connecting an analog signal of unknown magnitude to said pulse-producing means; and means for connecting the pulses from said pulse-producing means to count said first counting means for the time required for said fixed rate pulses to count said second counting means to a reference count whereby the count then in said first counting means is the digital representation of said analog signal.
Claim 6
Dependent Claim
194 words
The apparatus according to claim 3 wherein said means for generating a span calibration factor in said second counting means comprises: a digital storage means; means for transferring a stored calibration count to said second counting means; means for connecting for a predetermined time said first counting means to count in a first direction said pulses produced by connecting said first voltage source to said pulse-producing means for a predetermined time; means for connecting said first counting means to count in the other direction to a predetermined count said pulses produced by connecting a second voltage source to said pulse-producing means and simultaneously counting in said second counting means the fixed rate pulses; means for comparing the count in said second counting means with said calibration count; means in response to a noncompare indication for repeating the calibration after storing in said digital storage means as a new calibration count the count then in said second counting means; and means for terminating said span calibration operation on a compare indication whereby said span calibration factor is the count in the second counting meAns at the time said first counting means reaches the predetermined count.
Claim 7
Dependent Claim
105 words
The apparatus according to claim 3 wherein said means for generating a zero calibration factor in said first counting means comprises: means for storing the span calibration factor in said second counting means; means for connecting said first counting means to count in a first direction from a reference count said pulses produced by connecting the first voltage source to said pulse-producing means while simultaneously counting to said reference count in said second counting means in said first direction the fixed rate pulses whereby the zero calibration factor is the count in said first counting means when said second counting means reaches said reference count.
Claim 8
Dependent Claim
23 words
The apparatus according to claim 3 wherein said first reference voltage is zero volts and said second reference voltage is full scale voltage.
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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) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |