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Reference Voltage with Adjustable Temperature Coefficient

IP.com Disclosure Number: IPCOM000093134D
Original Publication Date: 1967-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Smith, WR: AUTHOR

Abstract

The circuit provides a highly stable reference voltage having a controlled temperature coefficient with a minimum of components and with a quick warm-up time. This circuit develops a temperature coefficient of -3mV/degrees C at a nominal reference voltage of -7.000 volts. This is achieved by use of a thermistor in parallel with a zener diode.

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Reference Voltage with Adjustable Temperature Coefficient

The circuit provides a highly stable reference voltage having a controlled temperature coefficient with a minimum of components and with a quick warm-up time. This circuit develops a temperature coefficient of -3mV/degrees C at a nominal reference voltage of -7.000 volts. This is achieved by use of a thermistor in parallel with a zener diode.

The output voltage is taken from point A. The value of this voltage is determined by the impressed voltage at point B and the divider action of resistors R1...R3. The latter are low temperature coefficient resistors. With a stable voltage impressed at point B and the resistors R1...R3 selected to provide good resolution about the output voltage, an extremely stable reference voltage is obtained at point A.

The voltage at point B is mainly determined by the V-I characteristics of the temperature-compensated zener reference diode ZR. The latter is characterized by a lower impedance than the impedance characteristics of the R1...R3 legs and thermistor leg R6. Thermistor R6 has a decreasing resistance characteristic with increasing temperature.

The combination of R4 and -V acts as a current source. The latter's value is determined by the recommended value of biasing current for ZR. In general, R4 is selected so that the resultant current through ZR is the manufacturer's recommended value of biasing cur current. The selection of ZR with a negligible temperature coefficient...