US3879668A
Expired / Lapsed
US
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Converter circuit
Assignee: HP Inc
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Filing: 1973-12-06
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Granted: 1975-04-22
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Expires: 1993-12-06
Abstract
Abstract A circuit is provided which produces a signal at the end of a time interval that is either directly proportional to an input voltage or proportional to the logarithm of an input voltage. The circuit includes an integrator for generating a very accurate exponential voltage output in response to an applied voltage and includes a comparator for comparing the exponential output voltage with a reference voltage. The comparator produces a signal which indicates the end of a time interval which is proportional to the logarithm of the input voltage. The comparator can also produce a signal at the end of a time interval which is directly proportional to the input voltage. The circuit may also include a network to compensate automatically for drifts and errors appearing at the input of the integrator.
Inventors
- 👤 Allen Ponsford Edwards
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:47
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/18; G06G7/184; G06G7/186; G06G7/1865; G06G7/24
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
177 words
A converter circuit for producing a signal which is proportional to the logarithm of an input signal, the circuit comprising: integrating means having an input and an output and including reactive impedance and being operable to integrate a signal applied thereto; first switching means connected to the input of said integrating means for applying an input signal thereto for the duration of an input period; circuit means including a discharge circuit and a second switching means connecting said discharge circuit to said reactive impedance of the integrating means for providing an exponentially-decaying signal at the output of the integrating means during a conversion period following the input period during which tHe second switching means is closed; comparator means including a source of reference signal and having an input connected to the output of the integrator for producing a signal at the output thereof to indicate the end of the conversion period in response to the exponentially-decaying signal applied to the input thereof from the output of said integrator means attaining a predetermined relationship to said reference signal.
Claim 2
Dependent Claim
177 words
A converter circuit for producing a signal which is proportional to the logarithm of an input signal, the circuit comprising: integrating means having an input and an output and including reactive impedance and being operable to integrate a signal applied thereto; first switching means connected to the input of said integrating means for applying an input signal thereto for the duration of an input period; circuit means including a discharge circuit and a second switching means connecting said discharge circuit to said reactive impedance of the integrating means for providing an exponentially-decaying signal at the output of the integrating means during a conversion period following the input period during which tHe second switching means is closed; comparator means including a source of reference signal and having an input connected to the output of the integrator for producing a signal at the output thereof to indicate the end of the conversion period in response to the exponentially-decaying signal applied to the input thereof from the output of said integrator means attaining a predetermined relationship to said reference signal.
Claim 3
Dependent Claim
177 words
A converter circuit for producing a signal which is proportional to the logarithm of an input signal, the circuit comprising: integrating means having an input and an output and including reactive impedance and being operable to integrate a signal applied thereto; first switching means connected to the input of said integrating means for applying an input signal thereto for the duration of an input period; circuit means including a discharge circuit and a second switching means connecting said discharge circuit to said reactive impedance of the integrating means for providing an exponentially-decaying signal at the output of the integrating means during a conversion period following the input period during which tHe second switching means is closed; comparator means including a source of reference signal and having an input connected to the output of the integrator for producing a signal at the output thereof to indicate the end of the conversion period in response to the exponentially-decaying signal applied to the input thereof from the output of said integrator means attaining a predetermined relationship to said reference signal.
Claim 4
Dependent Claim
177 words
A converter circuit for producing a signal which is proportional to the logarithm of an input signal, the circuit comprising: integrating means having an input and an output and including reactive impedance and being operable to integrate a signal applied thereto; first switching means connected to the input of said integrating means for applying an input signal thereto for the duration of an input period; circuit means including a discharge circuit and a second switching means connecting said discharge circuit to said reactive impedance of the integrating means for providing an exponentially-decaying signal at the output of the integrating means during a conversion period following the input period during which tHe second switching means is closed; comparator means including a source of reference signal and having an input connected to the output of the integrator for producing a signal at the output thereof to indicate the end of the conversion period in response to the exponentially-decaying signal applied to the input thereof from the output of said integrator means attaining a predetermined relationship to said reference signal.
Claim 5
Dependent Claim
98 words
A converter circuit as in claim 1 including a timing and logic means connected to the first and second switching means for controlling the closing and opening thereof: the first switching means being closed at the beginning of the input period to apply input signal to the integrating means and being opened at the end of this period; and the second switching means being closed at the beginning of the conversion period following the input period to produce the exponentially-decaying signal at the output of the integrating means and being opened at the end of the conversion period.
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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |