Balanced positive and negative voltage output circuit, in which error voltage for control is developed from difference in absolute value of positive and negative voltages referenced to a common point, regulates voltage for use with inertial reference unit. Fast-acting, temperature-compensated, high-gain operational amplifier circuits maintain common point

Crawford, R. A.

Hand, P. J.

English

NASA Technical Reports Server

1972	 B72-10092 
NASA TECH BRIEF 
NASA Pasadena Office 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Precision Voltage Regulator 
The problem: 
To design an efficient voltage regulator for use 
with an inertial reference unit; the voltage supplied 
to the integrator in the iiiertial unit must remain 
constant in spite of ambient temperature changes, 
input supply variations, and load changes resulting 
from demands by other circuits on the voltage 
regulator. 
The solution: 
A balanced positive and negative voltage output 
circuit in which the error voltage for control is de-
veloped from the difference in absolute value of the 
positive and negative voltages referenced to a com-
mon point. Fast-acting temperature-compensated, 
high-gain operational amplifier circuits maintain the 
common point at an equipotential value between 
the two. 
How it's done: 
The circuit is indicated schematically in the dia-
gram. A constant current is supplied to the precision, 
aged, temperature-compensated Zener diode CR1 by 
means of transistor Qi and associated components; 
variations of the Zener current due to the effect of 
temperature fluctuations on the V b. of Qi are auto-
matically compensated by changes in the value of 
the silicon resistor Ri (sensistor). The voltage drop 
across CR1 is compared by means of the high-gain 
monolithic operational amplifier Al with a similar 
voltage obtained by means of a voltage divider across 
the +V output and the common terminal. The ex-
tremely high gain of the amplifier (typically in 
excess of 150,000) causes the difference between these 
voltages to be very small, however, any variation
between the compared voltages is supplied as an 
error signal by Al to the series transistor Q2. The 
sense of the error signal is such as to cause the volt-
age drop across Q2 to decrease if the output voltage 
becomes lower, or to increase if the output voltage 
rises. 
4. I	 l,,.+A	 _I_I. (,.4 
- Unregulated 
Operational amplifier A2 is identical with Al and 
operates analogously; it compares the difference be-
tween the negative and positive output voltages with 
the output common point, thus causing the negative 
output voltage to track the positive output voltage. 
Error signals from A2 control the series transistor Q3 
in the same manner as those from Al control Q2. 
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the
	 - 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000092 2020-03-17T03:25:08+00:00Z
Notes: 
1. Output impedance at higher frequencies is re-
duced by Cl and C2. 
2. For maximum performance, all comparison and 
division resistors must be precision wire-wound 
types with low temperature coefficients, and the 
location of voltage-sensing points must be care-
fully controlled. 
8. Requests for further information may be di-
rected to: 
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP72-10092
Patent status: 
No patent action is contemplated by NASA. 
Source: Patrick J
.
 Hand and
Richard A. Crawford of
Caltech/JPL
under contract to
NASA Pasadena Office 
(NPO-11502) 
Category 01


Precision voltage regulator

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