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Adjusted Voltage Reference

IP.com Disclosure Number: IPCOM000087730D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Brunin, A: AUTHOR

Abstract

This circuit supplies a voltage reference VR to a current source TX, RX. When resistor RX has a low value, any variation in VR will entail comparatively important variations in the current flowing through source TX,RX. The voltage reference, therefore, must be adjusted in order to compensate for the variations in the current flowing through TX, this being achieved by stabilization of the voltage at the terminals of RX.

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Adjusted Voltage Reference

This circuit supplies a voltage reference VR to a current source TX, RX. When resistor RX has a low value, any variation in VR will entail comparatively important variations in the current flowing through source TX,RX. The voltage reference, therefore, must be adjusted in order to compensate for the variations in the current flowing through TX, this being achieved by stabilization of the voltage at the terminals of RX.

The voltage reference is obtained by means of a voltage dividing bridge R1,R3,T1,T2, which applies a potential reference to the base of the emitter- follower transistors T6 and T7 and to the current source including transistor T8 and resistor R5.

Adjusting the voltage with respect to the temperature is achieved by transistors T3,T4,T5 and resistor R4. Stabilizing the voltage at the terminals of RX comes to stabilize the voltage at the terminals of R3. Now, the current in R3 is supplied partially by circuit R1,T1,T2 and partially by circuit T3, R4. When raising the temperature, the current coming from R1 is increased, but transistor T3 will supply a smaller current to R3 so that the voltage drop in R3, owing to the current from transistor T3, tends to decrease, thereby achieving the voltage adjustment that compensates for the temperature change.

Resistor R6, connected between the base and the collector of transistor T8, achieves the NPN beta compensation, transistor T8 being identical with transistor TX.

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