US3873857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature sensor
Assignee: Sandoz AG
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Filing: 1974-01-10
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Granted: 1975-03-25
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Expires: 1994-01-10
Abstract
Abstract A temperature sensing circuit including a silicon transistor, and a differential amplifier connected to provide a constant current to the transistor, whereby the base-emitter voltage of the transistor varies linearly with its temperature at the rate of 2 mV/*C. The base electrode of the transistor forms the output of the differential amplifier and is applied through a voltagelevel adjusting second differential amplifier to a third amplifier which divides the base-emitter voltage by two, thereby providing a millivolt voltage reading measurable directly in *C. A switching device is provided to couple the output of the third amplifier directly to a meter, or to a conversion circuit which provides an output reading in *F. The conversion circuit includes a fourth amplifier which multiplies the third amplifier output by 9/5, and a fifth amplifier which adds a voltage equivalent to 32* to the output voltage from the fourth amplifier.
Inventors
- 👤 Dean T Farrish
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:50
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/01; H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
168 words
A solid state temperature sensor comprising a silicon transistor having emitter, base, and collector electrodes, and a first differential amplifier circuit connected to said transistor for supplying a constant collector current thereto, said differential amplifier having a first active element provided with input and output terminals, and having reference voltage means connected to said first input terminal, and a second active element provided with second input and output terminals, a series circuit comprising a fixed resistor connected with said collector and emitter electrodes, said series cirCuit being connected across a source of potential and having the junction between said fixed resistor and said transistor connected to said second input terminal, and said first output terminal being coupled to the base electrode of said silicon transistor, wherein the baseemitter voltage of said transistor, at said first output terminal, varies at the rate of 2mV/*C of the temperature of said silicon transistor while the collector current of said silicon transistor is maintained at a constant value by said differential amplifier.
Claim 2
Dependent Claim
168 words
A solid state temperature sensor comprising a silicon transistor having emitter, base, and collector electrodes, and a first differential amplifier circuit connected to said transistor for supplying a constant collector current thereto, said differential amplifier having a first active element provided with input and output terminals, and having reference voltage means connected to said first input terminal, and a second active element provided with second input and output terminals, a series circuit comprising a fixed resistor connected with said collector and emitter electrodes, said series cirCuit being connected across a source of potential and having the junction between said fixed resistor and said transistor connected to said second input terminal, and said first output terminal being coupled to the base electrode of said silicon transistor, wherein the baseemitter voltage of said transistor, at said first output terminal, varies at the rate of 2mV/*C of the temperature of said silicon transistor while the collector current of said silicon transistor is maintained at a constant value by said differential amplifier.
Claim 3
Dependent Claim
53 words
A solid state temperature sensor as set forth in claim 1 further comprising first conversion circuit means for controlling the reference level of said base-emitter voltage output from said first output terminal, and for dividing said voltage by a factor of 0.5 to provide a signal which varies at the rate of 1mV/*C.
Claim 4
Dependent Claim
125 words
A solid state temperature sensor as set forth in claim 2 wherein said first conversion circuit means comprises a second differential amplifier circuit having first and second inputs and an output, wherein said first input is connected to said first output terminal of said first differential amplifier, and said second input is adapted to be coupled to an adjustable reference potential, whereby said base-emitter voltage of said silicon transistor is coupled to said output of said second differential amplifier at a selected reference level; and a third amplifier having an input and an output, having a gain of 0.5, and having its input connected to the output of said second differential amplifier, whereby said 1mV/*C signal is provided at said output of said third amplifier.
Claim 5
Dependent Claim
28 words
A solid state temperature sensor as set forth in claim 2 further comprising second conversion circuit means for converting said 1 mV/*C signal to a signal of 1mV/*F.
Claim 6
Dependent Claim
196 words
A solid state temperature sensor as set forth in claim 4 wherein said first conversion circuit means comprises a second differential amplifier circuit having first and second inputs and an output, wherein said first input is connected to said first output terminal of said first differential amplifier, and said second input is adapted to be coupled to an adjustable reference potential, whereby said base-emitter voltage of said silicon transistor is coupled to said output of said second differential amplifier at a selected reference level, and a third amplifier having an input and an output, having a gain of 0.5, and having its input connected to the output of said second differential amplifier, whereby said 1mV/*C signal is provided at said output of said third amplifier; and said second conversion circuit means comprises a fourth amplifier having a gain of 9/5, and having an input connected to the output of said third amplifier, and output amplifying means having an input coupled to the output of said fourth amplifier for adding 32mV to the output voltage from said fourth amplifier, wherein the output from said output amplifying means corresponds to 1mV/*F of the temperature of said silicon transistor.
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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |