Miscellaneous active electrical nonlinear devices – circuits – and – External effect – Temperature
Patent
1998-09-03
2000-10-24
Le, Dinh T.
Miscellaneous active electrical nonlinear devices, circuits, and
External effect
Temperature
327512, 323314, G05F 526
Patent
active
061373419
ABSTRACT:
A temperature sensor circuit generates an output voltage that is linearly proportional to temperature over a desired temperature range with a desired offset voltage. The temperature sensor includes two Proportional To Absolute Temperature (PTAT) current sources that generate PTAT currents and two transistors which conduct the PTAT currents with different current densities to establish a basic voltage PTAT across a resistor. An offset resistor coupled between the bases of the two transistors and a circuit node, shifts the basic PTAT voltage by an offset voltage. A first gain circuit couples to the collector of the first transistor and the offset resistor and generates a servo current (i.e., a current that tends to move the circuit to the desired state by correcting an error) to servo the base of the first transistor when there is a difference between the first transistor's collector current and the PTAT current. A second gain circuit generates a second servo current to servo the emitter of the second transistor when there is a difference between the second transistor's collector current and the PTAT current. These servo currents drive the two transistors such that the second gain circuit generates a temperature related output voltage shifted from the basic voltage PTAT by the offset voltage, and which follows a predetermined temperature scale and has a substantially linear function with a desired offset temperature.
REFERENCES:
patent: 4497586 (1985-02-01), Nelson
patent: 4657658 (1987-04-01), Sibbald
patent: 5519354 (1996-05-01), Audy
Pease, Robert A., "A New Fahrenheit Temperature Sensor", IEEE Journal of Solid-State Circuits, vol. SC-19, No. 6. Dec. 1984, pp. 971-977.
Friedman Jay
Pease Robert Allen
Le Dinh T.
National Semiconductor Corporation
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