Patent US4364027A successfully refreshed from Google Patents.
US4364027A
Expired / Lapsed
US
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Calibration apparatus for analog-to-digital converter
Assignee: Tektronix Japan Corp
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Filing: 1981-02-09
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Granted: 1982-12-14
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Expires: 2001-02-09
Abstract
Abstract A calibration apparatus for analog-to-digital converter or transient recorder including both analog and digital sections is disclosed. A built-in calibrator automatically calibrates the gain and DC level of the entire system to substantially the same accuracy as that of the digital section, thereby avoiding relatively large errors of the analog section. The amplitude or gain calibration is always performed over the full range of the digitizer used in the digital section.
Inventors
- 👤 Rikichi Murooka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:36
CPC Classifications
G; G01; G01R; G01R35/00; G01R35/005; G01R13/00; G01R13/04; G01R13/06; H; H03; H03M; H03M1/00; H03M1/10
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
144 words
A calibration apparatus for an analog-to-digital converter, comprising: circuit means for controlling the DC level and the amplitude of an input signal applied thereto, the output signal from said circuit means being applied to said analog-to-digital converter; reference signal generator means for generating first, second and third reference levels to be applied to said circuit means, said first reference level being intermediate said second and third reference levels; and control means for controlling said circuit means in such a manner that the DC level of the output signal thereof is responsive to a digitized output from said analog-to-digital converter when the first reference level is applied to said circuit means, and that the amplitude of the output signal thereof is responsive to the difference between digitized outputs from said analog-to-digital converter when the second and third reference levels are applied to said circuit means.
Claim 2
Dependent Claim
144 words
A calibration apparatus for an analog-to-digital converter, comprising: circuit means for controlling the DC level and the amplitude of an input signal applied thereto, the output signal from said circuit means being applied to said analog-to-digital converter; reference signal generator means for generating first, second and third reference levels to be applied to said circuit means, said first reference level being intermediate said second and third reference levels; and control means for controlling said circuit means in such a manner that the DC level of the output signal thereof is responsive to a digitized output from said analog-to-digital converter when the first reference level is applied to said circuit means, and that the amplitude of the output signal thereof is responsive to the difference between digitized outputs from said analog-to-digital converter when the second and third reference levels are applied to said circuit means.
Claim 3
Dependent Claim
47 words
A calibration apparatus for an analog-to-digital converter according to claim 1, wherein the first, second and third reference levels from said reference signal generator means are chosen to be substantially equal to the center, maximum and minimum levels of the input analog window of said analog-to-digital converter.
Claim 4
Dependent Claim
54 words
A calibration apparatus for an analog-to-digital converter according to claim 2, wherein said circuit means includes an attenuator of at least two selectable attenuation factor, and the values of the first, second and third reference levels from said reference signal generator means are adjusted in response to the selected attenuation factor of said attenuator.
Claim 5
Dependent Claim
92 words
A calibration apparatus for an analog-to-digital converter according to claim 1, wherein said control means includes a microprocessor which compares the digitized output from said analog-to-digital converter corresponding to the first reference level with a predetermined value for conrolling the DC level of the input signal to said circuit means, and which calculates the difference between the digitized outputs from said analog-to-digital converter corresponding to the second and third reference levels and compares the calculated difference with a predetermined value for controlling the amplitude of the input signal to said circuit means.
Claim 6
Dependent Claim
44 words
A calibration apparatus for an analog-to-digital converter according to claim 1, wherein the first reference level is ground level, and said reference signal generator means includes a square-wave signal generator for alternately generating positive and negative voltages forming the second and third reference levels.
Claim 7
Dependent Claim
23 words
A calibration apparatus for an analog-to-digital converter according to claim 1, wherein said reference signal generator mens is actuated whenever calibration is necessary.
Claim 8
Dependent Claim
119 words
A transient recorder, comprising: an amplifier with controllable gain and DC level for amplifying an input analog signal; an analog-to-digital converter for digitizing the output signal from said amplifier; a memory for storing the digital output from said analog-to-digital converter; a calibrator for generating three different reference levels to be applied selectively to the input of said amplifier; and a control circuit responsive to the digital outputs from said analog-to-digital converter when the reference levels are applied to said amplifier for controlling the DC level of said amplifier in response to the intermediate value of the digital outputs and for controlling the gain thereof in response to the difference between the maximum and minimum values of the digital outputs.
Claim 9
Dependent Claim
119 words
A transient recorder, comprising: an amplifier with controllable gain and DC level for amplifying an input analog signal; an analog-to-digital converter for digitizing the output signal from said amplifier; a memory for storing the digital output from said analog-to-digital converter; a calibrator for generating three different reference levels to be applied selectively to the input of said amplifier; and a control circuit responsive to the digital outputs from said analog-to-digital converter when the reference levels are applied to said amplifier for controlling the DC level of said amplifier in response to the intermediate value of the digital outputs and for controlling the gain thereof in response to the difference between the maximum and minimum values of the digital outputs.
Claim 10
Dependent Claim
32 words
A transient recorder according to claim 7, wherein said calibrator generates a first reference level and second and third reference levels which are respectively higher and lower than the first reference level.
Claim 11
Dependent Claim
25 words
A transient recorder according to claim 8, wherein the second and third reference levels are substantially equal to the amplitude window of said transient recorder.
Claim 12
Dependent Claim
15 words
A transient recorder according to claim 8, wherein the first reference level is ground potential.
Claim 13
Dependent Claim
19 words
A transient recorder according to claim 7 further including a variable attenuator at the front stage of said amplifier.
Claim 14
Dependent Claim
23 words
A transient recorder according to claim 11, wherein said calibrator generates variable reference levels in response to the attenuation factor of said attenuator.
Claim 15
Dependent Claim
66 words
A transient recorder according to claim 7, wherein said control circuit includes a microprocessor which compares the intermediate value of the digital outputs with a predetermined value for controlling the DC level of said amplifier, and which calculates the difference between the maximum and minimum values of the digital outputs and compares the calculated difference with a predetermined value for controlling the gain of said amplifier.
Claim 16
Dependent Claim
21 words
A transient recorder according to claim 7, wherein said calibrator is actuated manually or automatically before digitizing the input analog signal.
References Cited (Backward Citations)
US3656053A
Cited
US3662380A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-12-13 | 1986-06-14 | 1986-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-13 | 1990-06-14 | 1990-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-13 | 1994-06-14 | 1994-12-14 | $7700.00 | Window Closed / Lapsed |