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Temperature Compensated Voltage Reference Source

IP.com Disclosure Number: IPCOM000075447D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Liu, CC: AUTHOR

Abstract

The figure shows a temperature-compensated programmable voltage-reference source. The voltage reference uses the negative temperature coefficient of the emitter-base voltage in conjunction with the positive temperature coefficient of the emitter-base voltage differential of two transistors operating at different current densities, to make a zero-temperature coefficient reference.

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Temperature Compensated Voltage Reference Source

The figure shows a temperature-compensated programmable voltage- reference source. The voltage reference uses the negative temperature coefficient of the emitter-base voltage in conjunction with the positive temperature coefficient of the emitter-base voltage differential of two transistors operating at different current densities, to make a zero-temperature coefficient reference.

Transistor Q1 is connected as a diode and is operated at a relatively high- current density. The current density of Q2 is about ten times lower, and the emitter-base voltage differential, delta VBE, between the two devices appears across resistor R3. If the transistors have high-current gains, the voltage across resistor R2 will be approximately equal to (R2/R3) delta VBE. Transistor Q3 is a gain stage that will regulate the output at a voltage equal to the voltage drop across R2 and the voltage at the base of transistor Q3. The voltage at the base of transistor Q3 is determined by the base-emitter voltage of transistor Q3 and the voltage from across the series of diodes that is placed in series with the emitter of transistor Q3.

The ratio of R2/R3 is changed according to the number of diodes in series with the emitter of transistor Q3. In a practical design, resistor R3 is held constant and resistor R2 is made of a string of resistors within n-identical increments, as shown above.

It can be shown that the output reference voltage of this...