US4581602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wide dynamic range analog to digital converter for AC signals
Assignee: Motorola Solutions Inc
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Filing: 1984-12-24
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Granted: 1986-04-08
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Expires: 2004-12-24
Abstract
Abstract A circuit for logarithmic analog to digital conversion is disclosed. An alternating current (AC) input signal of unknown level is logarithmically amplified, detected, and compared to an AC reference signal having a variable level and similarly amplified and detected. The comparison indicates which signal has a higher level and the level of the AC reference signal is responsively increased or decreased by an attenuation network having a plurality of related attenuation steps. When the signals are essentially equal, a digital representation is generated from the attenuation steps employed in attenuating the AC reference signal.
Inventors
- 👤 Elwood C. Reichart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 12:44
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/06; H03M1/0602; H03M1/0604; H03M1/0607
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
149 words
Analog to digital converter circuitry for use in converting a wide range input alternating current (AC) signal to a digital representation comprising: means for generating a reference AC signal; means for modifying said reference AC signal level by a plurality of modification steps corresponding to predetermined bit positions of the digital representation; means for logarithmically amplifying the AC input signal and said modified reference AC signal and for rectifying the amplified AC signals into corresponding direct current (DC) levels; means for determining if the modified and rectified reference AC signal DC level is greater or less than the rectified input AC signal DC level and for causing said modifying means to adjust said reference AC signal level to a smaller or greater level, respectively; and means for determining which modification steps are employed in modifying said reference AC signal level and for creating the digital representation from said determination.
Claim 2
Dependent Claim
149 words
Analog to digital converter circuitry for use in converting a wide range input alternating current (AC) signal to a digital representation comprising: means for generating a reference AC signal; means for modifying said reference AC signal level by a plurality of modification steps corresponding to predetermined bit positions of the digital representation; means for logarithmically amplifying the AC input signal and said modified reference AC signal and for rectifying the amplified AC signals into corresponding direct current (DC) levels; means for determining if the modified and rectified reference AC signal DC level is greater or less than the rectified input AC signal DC level and for causing said modifying means to adjust said reference AC signal level to a smaller or greater level, respectively; and means for determining which modification steps are employed in modifying said reference AC signal level and for creating the digital representation from said determination.
Claim 3
Dependent Claim
40 words
Analog to digital converter circuitry in accordance with claim 1 wherein said means for modifying said AC reference signal level is an attenuator which establishes a composite value of attenuation from a plurality of elements each having related attenuation values.
Claim 4
Dependent Claim
20 words
Analog to digital converter circuitry in accordance with claim 2 wherein said related attenuation values are related by geometric progression.
Claim 5
Dependent Claim
55 words
Analog to digital converter circuitry in accordance with claim 2 wherein said related attenuation values corresponding to a predetermined bit position have the element with the highest value of attenuation forming the most significant bit of the representation and the element with the lowest value of attenuation forming the least significant bit of the representation.
Claim 6
Dependent Claim
32 words
Analog to digital converter circuitry in accordance with claim 1 further comprising means for switching the input of said logarithmic amplifying means between the input AC signal and said reference AC signal.
Claim 7
Dependent Claim
27 words
Analog to digital converter circuitry in accordance with claim 5 further comprising means for filtering each said rectified AC signal in synchronism with said input switching means.
Claim 8
Dependent Claim
62 words
Analog to digital converter circuitry in accordance with claim 1 further comprising means for determining if the absolute value of said reference AC signal DC level exceeds the absolute value of the input AC signal DC level by a predetermined amount and for causing said modification means to adjust said reference AC signal level by selecting predetermined larger values of modification steps.
Claim 9
Dependent Claim
45 words
Analog to digital converter circuitry in accordance with claim 7 further comprising means for detecting when the modified reference AC signal DC level is essentially equal to the input AC signal DC level and ceasing to adjust said modification means in response to said detection.
Claim 10
Dependent Claim
31 words
Analog to digital converter circuitry in accordance with claim 1 wherein said means for generating an AC reference signal employs said means for logarithmically amplifying AC signals in an oscillator configuration.
Claim 11
Independent Claim
132 words
A method for converting a wide range input alternating current (AC) signal to a digital representation comprising the steps of: generating an reference AC signal; modifying said reference AC signal by a plurality of modification values corresponding to predetermined bit positions in the digital representation; logarithmically amplifying the AC input signal and said modified reference AC signal and rectifying the amplified AC signals into direct current (DC) levels; determining if the modified and rectified reference AC signal DC level is greater or less than the rectified AC input signal DC level and causing said modifying step to adjust said reference AC signal level to a smaller or greater level, respectively; and determining which modification values are employed in modifying said reference AC signal and creating the digital representation from said determination step.
Claim 12
Independent Claim
132 words
A method for converting a wide range input alternating current (AC) signal to a digital representation comprising the steps of: generating an reference AC signal; modifying said reference AC signal by a plurality of modification values corresponding to predetermined bit positions in the digital representation; logarithmically amplifying the AC input signal and said modified reference AC signal and rectifying the amplified AC signals into direct current (DC) levels; determining if the modified and rectified reference AC signal DC level is greater or less than the rectified AC input signal DC level and causing said modifying step to adjust said reference AC signal level to a smaller or greater level, respectively; and determining which modification values are employed in modifying said reference AC signal and creating the digital representation from said determination step.
Claim 13
Dependent Claim
31 words
A method in accordance with the method of claim 10, further comprising the step of switching between the input AC signal and said reference AC signal before logarithmically amplifying each signal.
Claim 14
Dependent Claim
26 words
A method in accordance with the method of claim 11, further comprising the step of filtering each rectified AC signal in synchronism with said switching step.
Claim 15
Dependent Claim
62 words
A method in accordance with the method of claim 10, further comprising the step of determining if the absolute value of said reference AC signal DC level exceeds the absolute value of the input AC signal DC level by a predetermined amount and causing said modification step to adjust said reference AC signal level by selecting predetermined larger values of modification values.
Claim 16
Dependent Claim
46 words
A method in accordance with the method of claim 13, further comprising the step of detecting when the modified reference AC signal DC level is essentially equal to the input AC signal DC level and ceasing adjustment of said modification step in response to said detection.
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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) | 1989-04-07 | 1989-10-07 | 1990-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-07 | 1993-10-07 | 1994-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-07 | 1997-10-07 | 1998-04-08 | $7700.00 | Window Closed / Lapsed |