US4608553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Analog to digital converter without zero drift
Assignee: Individual
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Filing: 1983-03-01
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Granted: 1986-08-26
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Expires: 2003-03-01
Abstract
Abstract The conversion is effected by adding equal and opposite reference voltages to the analog signal to provide two first output voltage levels. The voltage difference between these levels is converted into a first given number of pulses. The polarity of the analog signal is then reversed during the second half of the cycle so as to be subtracted from the reference voltages for providing two second output voltage levels. The voltage difference between these levels is converted into a second given number of pulses. A function of the first and second number of pulses provides a numerical count directly proportional to the analog signal with all zero drift eliminated. A second conversion can be made to provide a digital read-out which is free from both zero drift and span drift.
Inventors
- 👤 A. Neuman Ormond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:04
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/06; H03M1/08; H03M1/12; H03M1/50; H03M1/56
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
384 words
A system for converting an analog signal to a numerical digital count directly proportional to said analog signal without zero drift, including, in combination: (a) a differential operational amplifier means; (b) a source providing a reference voltage connected to said differential operational amplifier means; (c) a first reversing switch connected to pass said analog signal to the differential operational amplifier means such that the analog signal is added to the reference voltage when said switch is in a first position to provide two first output voltage levels; (d) a ramp voltage generating means; (e) two cross-over detectors connected to receive said two first output voltage levels respectively and a first ramp voltage from said ramp voltage generating means to provide first start and stop signals at points in time when said first ramp voltage crosses over said two first output voltage levels; (f) an oscillator for generating a series of clock pulses; (g) means for effecting a first conversion including a counter for said clock pulses connected to receive said first start and stop signals from said cross-over detectors to provide a first numerical count of N1 pulses, throwing of said first reversing switch to a second position resulting in said analog signal being subtracted from said reference voltage to provide two second output voltage levels from said differential operational amplifier means and result in second start and stop signals from said cross-over detectors when a second ramp voltage from said ramp voltage generator of the same slope as said first ramp voltage crosses over said two second output voltage levels, said second start and stop signals starting and stopping said counter to provide a second numerical count of N2 pulses; and, (h) means for dividing N1-N2 by N1+N2 to provide said numerical count, said differential operational amplifier means including an operational amplifier haveing a single ended input and ground terminals for receiving said analog signal and reference voltage signal, one of said first two output voltage levels constituting ground voltage level and the other the output from said operational amplifier when said analog signal is added to said reference voltage, and one of said second two output voltage levels constituting ground voltage level and the other the output level from said operational amplifier when said analog signal is subtracted from said reference voltage.
Claim 2
Independent Claim
384 words
A system for converting an analog signal to a numerical digital count directly proportional to said analog signal without zero drift, including, in combination: (a) a differential operational amplifier means; (b) a source providing a reference voltage connected to said differential operational amplifier means; (c) a first reversing switch connected to pass said analog signal to the differential operational amplifier means such that the analog signal is added to the reference voltage when said switch is in a first position to provide two first output voltage levels; (d) a ramp voltage generating means; (e) two cross-over detectors connected to receive said two first output voltage levels respectively and a first ramp voltage from said ramp voltage generating means to provide first start and stop signals at points in time when said first ramp voltage crosses over said two first output voltage levels; (f) an oscillator for generating a series of clock pulses; (g) means for effecting a first conversion including a counter for said clock pulses connected to receive said first start and stop signals from said cross-over detectors to provide a first numerical count of N1 pulses, throwing of said first reversing switch to a second position resulting in said analog signal being subtracted from said reference voltage to provide two second output voltage levels from said differential operational amplifier means and result in second start and stop signals from said cross-over detectors when a second ramp voltage from said ramp voltage generator of the same slope as said first ramp voltage crosses over said two second output voltage levels, said second start and stop signals starting and stopping said counter to provide a second numerical count of N2 pulses; and, (h) means for dividing N1-N2 by N1+N2 to provide said numerical count, said differential operational amplifier means including an operational amplifier haveing a single ended input and ground terminals for receiving said analog signal and reference voltage signal, one of said first two output voltage levels constituting ground voltage level and the other the output from said operational amplifier when said analog signal is added to said reference voltage, and one of said second two output voltage levels constituting ground voltage level and the other the output level from said operational amplifier when said analog signal is subtracted from said reference voltage.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-25 | 1990-02-24 | 1990-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-25 | 1994-02-24 | 1994-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-25 | 1998-02-24 | 1998-08-26 | $7700.00 | Window Closed / Lapsed |