Browse Prior Art Database

Temperature Sensing and Compensating Reference Voltage Supplies

IP.com Disclosure Number: IPCOM000095937D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Martin, WL: AUTHOR

Abstract

A temperature tracking reference voltage is produced by circuits which have a manually adjustable output level.

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Temperature Sensing and Compensating Reference Voltage Supplies

A temperature tracking reference voltage is produced by circuits which have a manually adjustable output level.

Circuit A operates from a constant input voltage E such as might be produced by a Zener diode. The initial output level from transistor 10 is manually adjustable by potentiometer 11. The output voltage tracks the temperature sensed by thermistor 12 and, for an increasing temperature and positive temperature coefficient for 12, rises with an initial slope determined by both 11 and 12. After the output reaches a predetermined level in accordance with the setting of potentiometer 15, diode 16 conducts and then reduces the overall temperature coefficient of the circuit as a result of the reduced impedance seen by the base of
10.

Circuit B produces an output voltage which tracks the temperature sensed by thermistor 20 while being relatively insensitive to temperature variations within the circuit. Power source E is relatively unregulated, but power sources E1 and E2 are constant voltage sources such as from Zener circuitry. Transistors 21 and 22 are PNP - NPN combinations, as are transistors 23 and 24, to minimize temperature drift sensed at node 25 due to changes in emitter to base voltage in these transistors. Thus, one current component into 25 is a current which is relatively proportional to the temperature tracked at 20. The temperature coefficient of this first current is manually adjustable by potentiometer 26. A second current component into 25 is adjustab...