Gyrator circuits using only transistors, capacitors, and resistors which can replace both grounded and ungrounded inductors have been developed to permit complete microminiaturization of circuitry by integration of the components

Deboo, G. J.

English

NASA Technical Reports Server

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March 1968	 Brief 68-10084 
NASA TECH BRIEF 
_& 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Gyrator-Type Circuits Replace Ungrounded Inductors 
TWO-AMPLIFIER GYRATOR
(CIRCUIT NO.1) 
The problem: 
To design an electronic circuit that does not use 
inductors, yet will perform the same function as one 
using inductors. The purpose is to permit complete 
microminiaturization of circuitry by integration of the 
components, since inductors having values in excess of 
a few microhenries are difficult, if not impossible, to 
integrate. 
The solution: 
Gyrator circuits using only transistors, capacitors, 
and resistors which can replace both grounded and 
ungrounded inductors. Circuits having effective 
inductances of hundreds of henries have been success-
fully built. Filters utilizing these circuits have 
achieved frequency responses closer to the ideal than 
circuits with real inductors.
TWO-AMPLIFIER GYRATOR 
(CIRCUIT NO. 2) 
How its done: 
Two gyrator circuits were designed using two opera-
tional amplifiers in each. Each can be used to simulate 
a grounded inductor. Normally, an ungrounded in-
ductor would be replaced by two gyrators and a 
capacitor, for a total of four amplifiers in the circuit. 
However, when these two gyrators are combined and 
terminated with a capacitor, only three operational 
amplifiers are required. 
Notes: 
I. Additional details are contained in: Application of 
a Gyrator-Type Circuit to Ungrounded Inductors, 
by Gordon J. Deboo, IEEE Transactions on Cir-
cuit Theory, vol. CT-l4, no. I, p. 101-102, March 
1967. 
2. Another solution to the problem, based on a totally 
different design philosophy is given in NASA Tech 
Brief 66-10309, available from the Clearinghouse 
for Federal Scientific and Technical Information, 
Springfield, Virginia 22151; price $0.15.
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000084 2020-03-12T05:49:10+00:00Z
2Inquiries concerning these circuits may be di-
rected to:
Technology Utilization Officer 
Ames Research Center 
Moffett Field , California 94035 
Reference: B68-10084
Patent status: 
This invention is owned by NASA, and a patent

application has been filed. Royalty-free, nonexclusive

licenses for its commercial use will be granted by

NASA. Inquiries concerning license rights should be

made to NASA, Code GP, Washington, D.C. 20546.

Source: Gordon J. Deboo

(XAC- 10608) 
R	 213 
COMBINED GYRATOR CIRCUIT 
Brief 68-10084 Category 01


Gyrator-type circuits replace ungrounded inductors

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