Browse Prior Art Database

Stable Voltage Reference Circuit

IP.com Disclosure Number: IPCOM000084587D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Gersbach, JE: AUTHOR

Abstract

This is a reference voltage circuit that is very stable with respect to temperature. The circuit uses a current switch and a feedback loop, including one leg of the current switch and a transistor complimentary to the transistors of the current switch to establish a fixed voltage across a reference diode set, which voltage is independent of the temperatures to which the circuit is subjected.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Stable Voltage Reference Circuit

This is a reference voltage circuit that is very stable with respect to temperature. The circuit uses a current switch and a feedback loop, including one leg of the current switch and a transistor complimentary to the transistors of the current switch to establish a fixed voltage across a reference diode set, which voltage is independent of the temperatures to which the circuit is subjected.

The circuit shown in the figure provides an output voltage Vref which is independent of power supply (+V) variations and of temperature. Two functions are provided within the circuit. First, the current in the reference diode set (DI, DZ) is stabilized, and secondly, the output terminal is buffered from the reference diode set to boost the output current capability.

Assuming the current in resistor R1 splits evenly between transistors T1 and T2, half of R1's current flows in transistor T1 and half in transistor T3. Since, however, transistor T4 is in parallel with transistor T3, a proportional current also flows in transistor T4 and in the reference diode set D1 and DZ. The voltage across the reference diode set is impressed on resistor R1 through transistor T1, diode D2 and diode D3, completing the loop. The current in the reference diode set D1, DZ is therefore proportional to the voltage drop across the set.

The stability of this current can be easily analyzed by drawing a load line representing a reference diode on the same graph as the voltage vs current characteristics of node A without the diodes. When, for example, the diode current source is appr...