Patent US3668428A successfully refreshed from Google Patents.
US3668428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Root mean square measuring circuit
Assignee: Texas Instruments Tucson Corp
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Filing: 1970-08-10
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Granted: 1972-06-06
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Expires: 1990-08-10
Abstract
Abstract A pair of semiconductor junction devices, such as transistors, are connected in a common emitter configuration with suitable forward biasing. The junction devices are matched and each is associated with one of a pair of matched resistors. Heat transfer means connects each resistor with one of the junction devices; heat generated in the resistor is transmitted to the junction device to cause temperature variations therein. The circuit elements, such as transistors, exhibit a forward voltage drop that is a function of the temperature of the element; the voltage drops across the transistors therefore vary as a result of the power being dissipated by the associated resistor. The transistors are connected to a differential amplifier which senses and amplifies the differential voltage resulting from the different voltage drops and produces an output signal in response thereto. The output signal is connected in a feedback loop to one of the matched resistors while an input terminal is provided to the second matched resistor for connecting thereto a signal to be measured.
Inventors
- 👤 Henry Koerner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:59
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/20; G01; G01R; G01R19/00; G01R19/02; G01R19/03; G01R19/22; G01R19/225
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
190 words
A root mean square measuring circuit comprising: first and second matched resistors; first and second matched transistors, each having a continuous voltage drop thereacross a function of temperature, and each having an emitter electrode connected to the emitter electrode of the other; a pair of resistors, each connected to a collector electrode of one of a different one of said transistors, said resistors connected to each other; a biasing source connected between the junction of said emitters and the junction of said resistors; a differential amplifier connected between the junctions formed by the connection of said resistors with said collector electrodes for continuously generating an output signal in response to a difference in voltage drop across said transistors; means for connecting said first matched resistor to a signal to be measured by heating said first matched resistor; means for electrically isolating said input signal and said first resistor from the remaining circuitry; feedback means connecting said continuously generated output signal to said second matched resistor for heating said second matched resistor, whereby said voltage drop across said second transistor is made equal to the voltage drop across said first transistor.
Claim 2
Dependent Claim
190 words
A root mean square measuring circuit comprising: first and second matched resistors; first and second matched transistors, each having a continuous voltage drop thereacross a function of temperature, and each having an emitter electrode connected to the emitter electrode of the other; a pair of resistors, each connected to a collector electrode of one of a different one of said transistors, said resistors connected to each other; a biasing source connected between the junction of said emitters and the junction of said resistors; a differential amplifier connected between the junctions formed by the connection of said resistors with said collector electrodes for continuously generating an output signal in response to a difference in voltage drop across said transistors; means for connecting said first matched resistor to a signal to be measured by heating said first matched resistor; means for electrically isolating said input signal and said first resistor from the remaining circuitry; feedback means connecting said continuously generated output signal to said second matched resistor for heating said second matched resistor, whereby said voltage drop across said second transistor is made equal to the voltage drop across said first transistor.
Claim 3
Dependent Claim
173 words
A root mean square measuring circuit comprising: first and second resistors; first and second semi-conductor junctions, each having a voltage drop thereacross a known function of junction temperature; biasing means connected to said semiconductor junctions for continuously developing a voltage drop across each; heat transfer means thermally connecting said first resistor to said first semiconductor junction, and heat transfer means thermally connecting said second resistor and said second semiconductor junction; differential amplifier means connected to said first and second semiconductor junctions responsive to a difference in the voltage drops across said semiconductor junctions for continuously generating an output signal; means for connecting said first resistor to a signal to be measured for heating said first resistor; means for electrically isolating said input signal and said first resistor from the remaining circuitry; feedback means connecting said continuously generated output signal to said second resistor for heating said second resistor whereby said voltage drop across said second semiconductor junction is made equal to a known function of the voltage drop across said first semiconductor junction.
Claim 4
Dependent Claim
173 words
A root mean square measuring circuit comprising: first and second resistors; first and second semi-conductor junctions, each having a voltage drop thereacross a known function of junction temperature; biasing means connected to said semiconductor junctions for continuously developing a voltage drop across each; heat transfer means thermally connecting said first resistor to said first semiconductor junction, and heat transfer means thermally connecting said second resistor and said second semiconductor junction; differential amplifier means connected to said first and second semiconductor junctions responsive to a difference in the voltage drops across said semiconductor junctions for continuously generating an output signal; means for connecting said first resistor to a signal to be measured for heating said first resistor; means for electrically isolating said input signal and said first resistor from the remaining circuitry; feedback means connecting said continuously generated output signal to said second resistor for heating said second resistor whereby said voltage drop across said second semiconductor junction is made equal to a known function of the voltage drop across said first semiconductor junction.
Claim 5
Dependent Claim
45 words
The combination set forth in claim 1, wherein said first and second resistors are matched and said first and second sensing elements are matched, whereby said voltage drop across said second sensing element is made equal to the voltage drop across said first sensing element.
Claim 6
Dependent Claim
13 words
The combination set forth in claim 1, wherein said semiconductor junctions are forward-biased.
Claim 7
Dependent Claim
17 words
The combination set forth in claim 4, wherein said forward-biased semiconductor junctions are junctions of semiconductor diodes.
Claim 8
Dependent Claim
16 words
The combination set forth in claim 4, wherein said forward-biased semiconductor junctions are junctions of transistors.
Claim 9
Dependent Claim
45 words
The combination set forth in claim 6, wherein said first and second resistors are matched and said first and second sensing elements are matched whereby said voltage drop across said second sensing element is made equal to the voltage drop across said first sensing element.
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) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |