US5101206A
Expired / Lapsed
US
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Integrating analog to digital converter
Assignee: Agilent Technologies Inc
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Filing: 1989-12-05
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Granted: 1992-03-31
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Expires: 2009-12-05
Abstract
Abstract An integrating analog-to-digital converter (ADC) which calculates the coarse portion of its output by integrating an input analog signal over a predetermined number of time intervals during runup using a known technique to define the analog signal in terms of a slope count. The invention is particularly characterized in that an ADC is used in lieu of rundown of the integrator voltage to calculate the fine portion of the ADC output also in terms of slope count. This is accomplished by converting the residual analog signal remaining at the end of runup into a fractional slope count which can be added to the slope count determined during runup so that the resulting total slope count is directly proportional to the input voltage. To maintain linearity, calibration of the circuit is necessary and is accomplished by calculating a calibration constant which relates the ADC reading to slope count. The resulting calibration constant is then multiplied by the ADC output representative of the residual integrator voltage in order to determine the slope count representative of the residual integrator voltage. Such calibration is performed periodically in order to account for time and temperature fluctuations caused by ambient conditions.
Inventors
- 👤 Ronald J. Riedel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:23
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/14; H03M1/50; H03M1/52
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
142 words
An analog-to-digital converter for converting an input analog signal into an output digital signal, comprising: means for integrating said input analog signal over a predetermined number of time intervals, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for the remaining number of said predetermined time intervals corresponding to a negative slope count; means for converting a residual analog signal remaining at the end of said predetermined number of time intervals into a residual digital signal; and means for calibrating said residual digital signal so as to represent a fractional number of slope counts, whereby the output digital signal is determined from a total slope count substantially equal to the sum of (1) said fractional number of slope counts and (2) the difference between said positive and negative slope counts.
Claim 2
Dependent Claim
142 words
An analog-to-digital converter for converting an input analog signal into an output digital signal, comprising: means for integrating said input analog signal over a predetermined number of time intervals, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for the remaining number of said predetermined time intervals corresponding to a negative slope count; means for converting a residual analog signal remaining at the end of said predetermined number of time intervals into a residual digital signal; and means for calibrating said residual digital signal so as to represent a fractional number of slope counts, whereby the output digital signal is determined from a total slope count substantially equal to the sum of (1) said fractional number of slope counts and (2) the difference between said positive and negative slope counts.
Claim 3
Dependent Claim
16 words
An analog-to-digital converter as in claim 1, wherein said integrating means comprises a multislope runup circuit.
Claim 4
Dependent Claim
16 words
An analog-to-digital converter as in claim 2, wherein said converting means comprises a residual analog-to-digital converter.
Claim 5
Dependent Claim
27 words
An analog-to-digital converter as in claim 3, wherein said calibrating means calibrates said residual digital signal by effectively multiplying said residual digital signal by a calibration constant.
Claim 6
Dependent Claim
79 words
An analog-to-digital converter as in claim 4, wherein said calibration constant has a magnitude substantially equal to a magnitude of a full scale voltage of said residual analog-to-digital converter divided by a sum of a absolute values of respective residual voltages left on said multislope runup circuit due to a change of one in the positive slope count and a change of one in the negative slope count when no external input is applied to said multislope runup circuit.
Claim 7
Dependent Claim
43 words
An analog-to-digital converter as in claim 5, wherein a magnitude of said total slope count substantially equals a sum of (1) a difference between said positive and negative slope counts and (2) a product of said calibration constant with said residual digital signal.
Claim 8
Dependent Claim
30 words
An analog-to-digital converter as in claim 6, wherein said calibrating means determines said output digital signal from a product of said total slope count with a global gain calibration constant.
Claim 9
Dependent Claim
25 words
An analog-to-digital converter as in claim 6, wherein said total slope count is substantially linearly proportional to a voltage magnitude of said input analog signal.
Claim 10
Dependent Claim
49 words
An analog-to-digital converter as in claim 6, wherein the difference between said positive and negative slope counts corresponds to most significant bits of said output digital signal and said product of said calibration constant with said residual digital signal corresponds to least significant bits of said output digital signal.
Claim 11
Dependent Claim
33 words
An analog-to-digital converter as in claim 1, wherein said integrating means comprises a dual-slope integrator having a single runup slope such that one of said positive and said negative slope counts is zero.
Claim 12
Dependent Claim
149 words
A digital multimeter for measuring the voltage of an input analog signal, comprising: means for integrating said input analog signal over a predetermined number of time intervals and thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for the remaining number of said predetermined time intervals corresponding to a negative slope count; means for converting a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal; and means for calibrating said residual digital signal so as to represent a fractional number of slope counts, whereby the voltage of said input analog signal is determined from a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2) a difference between said positive and negative slope counts.
Claim 13
Dependent Claim
149 words
A digital multimeter for measuring the voltage of an input analog signal, comprising: means for integrating said input analog signal over a predetermined number of time intervals and thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for the remaining number of said predetermined time intervals corresponding to a negative slope count; means for converting a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal; and means for calibrating said residual digital signal so as to represent a fractional number of slope counts, whereby the voltage of said input analog signal is determined from a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2) a difference between said positive and negative slope counts.
Claim 14
Dependent Claim
16 words
A digital multimeter as in claim 11, wherein said integrating means comprises a multislope runup circuit.
Claim 15
Dependent Claim
16 words
A digital multimeter as in claim 12, wherein said converting means comprises a residual analog-to-digital converter.
Claim 16
Dependent Claim
27 words
A digital multimeter as in claim 13, wherein said calibrating means calibrates said residual digital signal by effectively multiplying said residual digital signal by a calibration constant.
Claim 17
Dependent Claim
78 words
A digital multimeter as in claim 14, wherein said calibration constant has a magnitude substantially equal to a magnitude of a full scale voltage of said residual analog-to-digital converter divided by a sum of absolute values of respective residual voltages left on said multislope runup circuit due to a change of one in the positive slope count and a change of one in the negative slope count when no external input is applied to said multislope runup circuit.
Claim 18
Dependent Claim
43 words
A digital multimeter as in claim 15, wherein a magnitude of said total slope count substantially equals a sum of (1) a difference between said positive and negative slope counts and (2) a product of said calibration constant with said residual digital signal.
Claim 19
Dependent Claim
33 words
A digital multimeter as in claim 16, wherein said calibrating means determines the voltage of said input analog signal from a product of said total slope count with a global gain calibration constant.
Claim 20
Dependent Claim
27 words
A digital multimeter as in claim 16, wherein said total slope count is substantially linearly proportional to a magnitude of the voltage of said input analog signal.
Claim 21
Dependent Claim
55 words
A digital multimeter as in claim 16, wherein the difference between said positive and negative slope counts corresponds to most significant bits of the voltage of said input analog signal and said product of said calibration constant with said residual digital signal corresponds to least significant bits of the voltage of said input analog signal.
Claim 22
Dependent Claim
142 words
A digital multimeter for measuring the voltage of an input analog signal, comprising: a multislope runup circuit for integrating said input analog signal over a predetermined number of time intervals, said multislope runup circuit ramping positive for a first number of said predetermined number of time intervals and ramping negative for a second number of said predetermined number of time intervals; an analog-to-digital converter for converting a residual analog voltage output of said multislope runup circuit into a residual digital signal; and calibrating means for representing said residual digital signal as at least one fractional time interval of said multislope runup circuit, whereby a sum of (1) said at least one fractional time interval and (2) a difference between said first and second number of time intervals is substantially linearly proportional to a magnitude of the voltage of said input analog signal.
Claim 23
Dependent Claim
142 words
A digital multimeter for measuring the voltage of an input analog signal, comprising: a multislope runup circuit for integrating said input analog signal over a predetermined number of time intervals, said multislope runup circuit ramping positive for a first number of said predetermined number of time intervals and ramping negative for a second number of said predetermined number of time intervals; an analog-to-digital converter for converting a residual analog voltage output of said multislope runup circuit into a residual digital signal; and calibrating means for representing said residual digital signal as at least one fractional time interval of said multislope runup circuit, whereby a sum of (1) said at least one fractional time interval and (2) a difference between said first and second number of time intervals is substantially linearly proportional to a magnitude of the voltage of said input analog signal.
Claim 24
Independent Claim
149 words
A method of converting an input analog signal into an output digital signal, comprising the steps of: integrating said input analog signal over a predetermined number of time intervals and thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for a remaining number of said predetermined time intervals corresponding to a negative slope count; converting a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal using a residual analog-to-digital converter; and calibrating said residual digital signal so as to represent a fractional number of slope counts, whereby the output digital signal is determined from a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2) a difference between said positive and negative slope counts.
Claim 25
Independent Claim
149 words
A method of converting an input analog signal into an output digital signal, comprising the steps of: integrating said input analog signal over a predetermined number of time intervals and thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for a remaining number of said predetermined time intervals corresponding to a negative slope count; converting a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal using a residual analog-to-digital converter; and calibrating said residual digital signal so as to represent a fractional number of slope counts, whereby the output digital signal is determined from a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2) a difference between said positive and negative slope counts.
Claim 26
Dependent Claim
17 words
A method as in claim 21, wherein said integrating step is performed by a multislope runup circuit.
Claim 27
Dependent Claim
24 words
A method as in claim 22, wherein said calibrating step includes the step of effectively multiplying said residual digital signal by a calibration constant.
Claim 28
Dependent Claim
84 words
A method as in claim 23, wherein said calibrating step further includes a step of calculating the magnitude of said calibration constant by dividing a magnitude of a full scale voltage of said residual analog-to-digital converter by a sum of absolute values of respective residual voltages left on said multislope runup circuit due to a change of one in the positive slope count and a change of one in the negative slope count when no external input is applied to said multislope runup circuit.
Claim 29
Dependent Claim
46 words
A method as in claim 24, including the further step of calculating a magnitude of said total slope count as the sum of (1) a product of said calibration constant with said residual digital signal and (2) a difference between said positive and negative slope counts.
Claim 30
Dependent Claim
30 words
A method as in claim 25, including a further step of determining said output digital signal from the product of said total slope count with a global gain calibration constant.
Claim 31
Dependent Claim
53 words
A method as in claim 25, including the further step of outputting the difference between said positive and negative slope counts as the most significant bits of said output digital signal and said product of said calibration constant with said residual digital signal as the least significant bits of said output digital signal.
Claim 32
Independent Claim
147 words
A method of measuring the voltage of an input analog signal, comprising the steps of: integrating said input analog signal over a predetermined number of time intervals thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for a remaining number of said predetermined time intervals corresponding to a negative slope count; converting a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal using a residual analog-to-digital converter; calibrating said residual digital signal so as to represent a fractional number of slope counts; and calculating the voltage of said input analog signal from a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2) a difference between said positive and negative slope counts.
Claim 33
Independent Claim
147 words
A method of measuring the voltage of an input analog signal, comprising the steps of: integrating said input analog signal over a predetermined number of time intervals thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for a remaining number of said predetermined time intervals corresponding to a negative slope count; converting a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal using a residual analog-to-digital converter; calibrating said residual digital signal so as to represent a fractional number of slope counts; and calculating the voltage of said input analog signal from a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2) a difference between said positive and negative slope counts.
Claim 34
Dependent Claim
17 words
A method as in claim 28, wherein said integrating step is performed by a multislope runup circuit.
Claim 35
Dependent Claim
24 words
A method as in claim 29, wherein said calibrating step includes the step of effectively multiplying said residual digital signal by a calibration constant.
Claim 36
Dependent Claim
84 words
A method as in claim 30, wherein said calibrating step further includes a step of calculating the magnitude of said calibration constant by dividing a magnitude of a full scale voltage of said residual analog-to-digital converter by a sum of absolute values of respective residual voltages left on said multislope runup circuit due to a change of one in the positive slope count and a change of one in the negative slope count when no external input is applied to said multislope runup circuit.
Claim 37
Dependent Claim
49 words
A method as in claim 31, wherein said calculating step includes the step of calculating a magnitude of said total slope count as a sum of (1) a product of said calibration constant with said residual digital signal and (2) a difference between said positive and negative slope counts.
Claim 38
Dependent Claim
36 words
A method as in claim 32, wherein said calculating step includes the step of determining the voltage of said input analog signal from a product of said total slope count with a global gain calibration constant.
Claim 39
Dependent Claim
60 words
A method as in claim 32, wherein said calculating step includes the step of representing the difference between said positive and negative slope counts as most significant bits of the voltage of said input analog signal and said product of said calibration constant with said residual digital signal as least significant bits of the voltage of said input analog signal.
Claim 40
Independent Claim
290 words
A method of converting an input analog signal into an output digital signal, comprising the steps of: (1) integrating said input analog signal with an integrator over a predetermined number of time intervals thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for a remaining number of said predetermined time intervals corresponding to a negative slope count; (2) converting, with a residual analog-to-digital converter, a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal; (3) zeroing said integrator; (4) removing all external inputs from said integrator to allow said integrator to ramp positive for a duration of one of said predetermined time intervals; (5) after said duration of one predetermined time interval, sampling and storing an integrator output V1; (6) rezeroing said integrator; (7) removing all external inputs from said integrator to allow said integrator to ramp negative for a duration of one of said predetermined time intervals; (8) after said duration of one predetermined time interval, sampling and storing an integrator output V2; (9) calculating a calibration constant as a quotient of a magnitude of a full voltage range of said residual analog-to-digital converter divided by a sum of a absolute values of V1 and V2; (10) calibrating said residual digital signal by effectively multiplying said residual digital signal by said calibration constant so as to represent a fractional number of slope counts; and (11) calculating a output digital signal from a magnitude of a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2), a difference between said positive and negative slope counts.
Claim 41
Independent Claim
290 words
A method of converting an input analog signal into an output digital signal, comprising the steps of: (1) integrating said input analog signal with an integrator over a predetermined number of time intervals thereby producing an integrated output, the integrated output being positive for a number of said predetermined time intervals corresponding to a positive slope count and negative for a remaining number of said predetermined time intervals corresponding to a negative slope count; (2) converting, with a residual analog-to-digital converter, a residual analog signal remaining at an end of said predetermined number of time intervals into a residual digital signal; (3) zeroing said integrator; (4) removing all external inputs from said integrator to allow said integrator to ramp positive for a duration of one of said predetermined time intervals; (5) after said duration of one predetermined time interval, sampling and storing an integrator output V1; (6) rezeroing said integrator; (7) removing all external inputs from said integrator to allow said integrator to ramp negative for a duration of one of said predetermined time intervals; (8) after said duration of one predetermined time interval, sampling and storing an integrator output V2; (9) calculating a calibration constant as a quotient of a magnitude of a full voltage range of said residual analog-to-digital converter divided by a sum of a absolute values of V1 and V2; (10) calibrating said residual digital signal by effectively multiplying said residual digital signal by said calibration constant so as to represent a fractional number of slope counts; and (11) calculating a output digital signal from a magnitude of a total slope count substantially equal to a sum of (1) said fractional number of slope counts and (2), a difference between said positive and negative slope counts.
Claim 42
Dependent Claim
24 words
A method as in claim 35, wherein said steps (3)- (10) are periodically executed to keep said output digital signal substantially linear and calibrated.
Claim 43
Dependent Claim
47 words
A method as in claim 36, wherein said calculating step (11) includes the step of calculating said total slope count as a sum of (1) a product of said calibration constant with said residual digital signal and (2) a difference between said positive and negative slope counts.
Claim 44
Dependent Claim
34 words
A method as in claim 37, wherein said calculating step includes a further step of determining said output digital signal from the product of said total slope count with a global gain calibration constant.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-31 | 1995-09-30 | 1996-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-31 | 1999-09-30 | 2000-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-31 | 2003-09-30 | 2004-03-31 | $7700.00 | Window Closed / Lapsed |