US4529966A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High-speed bipolar logarithmic analog-to-digital converter
Assignee: UNITES STATES OF AMERICA AS REPRESENTED BY DEPARTMENT OF NAVY
•
Filing: 1983-10-11
•
Granted: 1985-07-16
•
Expires: 2003-10-11
Abstract
Abstract A high-speed bipolar logarithmic analog-to-digital (A/D) converter outputs signed binary number proportional to the logarithm of a bipolar analog input signal. A log converter is followed by a level shifting amplifier to center the output of the log converter on a temperature compensating reference. The reference voltage from the temperature compensating reference is used by a linear A/D converter to set the end points of the converter range. A code converter follows the A/D converter if a uniform absolute value coding is desired. Limiting the number of least significant bits (LSB) used to those representing the range of usable converter operation completes the device.
Inventors
- 👤 James A. Burroughs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:15
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/1235
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
95 words
A bipolar logarithmic analog-to-digital converter comprising; a log converter having an output level in logarithmic conformity to an input driving current; a temperature compensating reference circuit having a maximum, usable reference current input; means for converting said output level from said log converter to a digital signal, said converting means using an external reference and said external reference being derived from said temperature compensating reference circuit; and a level shifting amplifier following said log converter to center said log converter output level on a temperature compensating voltage reference derived from said temperature compensating reference circuit.
Claim 2
Dependent Claim
95 words
A bipolar logarithmic analog-to-digital converter comprising; a log converter having an output level in logarithmic conformity to an input driving current; a temperature compensating reference circuit having a maximum, usable reference current input; means for converting said output level from said log converter to a digital signal, said converting means using an external reference and said external reference being derived from said temperature compensating reference circuit; and a level shifting amplifier following said log converter to center said log converter output level on a temperature compensating voltage reference derived from said temperature compensating reference circuit.
Claim 3
Dependent Claim
38 words
An analog-to-digital converter as recited in claim 1 further comprising a code converter following said converting means for inversion of the number of used least significant bits when the most significant bit from said converting means is one.
Claim 4
Dependent Claim
35 words
An analog-to-digital converter as recited in claim 1 wherein said log converter comprises: an operational amplifier; and a logarithmic response transducer suitable for two polarity operation connected in the feedback loop of said operational amplifier.
Claim 5
Dependent Claim
26 words
An analog-to-digital converter as recited in claim 3 wherein said logarithmic response transducer comprises a pair of complementary logging transistors connected in the common base mode.
Claim 6
Dependent Claim
56 words
An analog-to-digital converter as recited in claim 4 wherein said temperature compensating reference circuit comprises a pair of complementary reference transistors connected in a common emitter mode with said emitter providing said temperature compensating voltage reference and the respective collector-base outputs providing said external reference, said complementary reference transistors being matched to said complementary logging transistors.
Claim 7
Dependent Claim
64 words
An analog-to-digital converter as recited in claim 5, wherein said level shifting amplifier comprises: a first operational amplifier connected between said log converter and said converting means to pass said output level to said converting means; and a second operational amplifier connected between said temperature compensating reference circuit and said first operational amplifier to center said output level on said temperature compensating voltage reference.
References Cited (Backward Citations)
US3653033A
Cited
US3811125A
Cited
US4005410A
Cited
US3940760A
Cited
US4168492A
Cited
US4156233A
Cited
US4275386A
Cited
US4490713A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-07-15 | 1989-01-14 | 1989-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-15 | 1993-01-14 | 1993-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-15 | 1997-01-14 | 1997-07-16 | $7700.00 | Window Closed / Lapsed |