Circuit generates an output pulse of fixed width from a variable width input pulse. The circuit consists of a tunnel diode in parallel with an inductance driven by a constant current generator. It is used for pulsed communication equipment design

Garrahan, N. M.

English

NASA Technical Reports Server

August I965
	
Aso 3	 Brief 65-10228 
NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Simple Circuit Produces High-Speed, Fixed Duration Pulses 
Constant Current

Generator 
LTIIIIIIIIIi
Tunnel 
Input	 Diode
Output
Fixed Duration 
Output Pulse 
Inductor IHF1 
Variable Duration
Input Pulse 
The problem: To generate in output pulse of fixed 
duration from a variable duration input pulse ranging 
from 50 to several hundred nanoseconds. Prior art 
differentiated the input pulse to obtain a trigger pulse 
to be applied to a monostable or blocking oscillator. 
This method requires com plcx circuitry that consumes 
a relativel y large amount of po\er. 
The solution: A circuit consistine of a tunnel diode 
in parallel with an inductance driven b y a constant-
current generator. Input pulses of variable width in the 
nanosecond range ViCILI output pulses of fixed width. 
How it's done: The variable duration pulse applied 
to the input of the constant-current generator allows
a current to how through the parallel network. When 
this current is first applied to the parallel network, the 
initial high impedance of the inductor causes the entire 
current to how through the tunnel diode. This current 
is adjusted to he greater than the peak current of the 
tunnel diode, causing the tunnel diode to switch to its 
high-voltage state. Current through the inductor, ini-
tially zero, increases with time and the tunnel diode 
current and voltage decrease until the valley point of 
the tunnel diode is reached, causing it to switch to its 
low-voltage state. Because the inductor now has a 
relativel y
 low impedance, the output voltage will be 
approximatel y zero for the duration 01'111C input pulse. 
(continued in erkai( 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000226 2020-03-11T17:19:08+00:00Z
Notes 
1. Close control of output pulse width is easily ac-
complished by varying the value of the inductor. 
2. This circuit should be of interest to designers of 
computer and pulsed communications equipment. 
3. Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland, 20771 
Reference: B65-10228
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about ob-
taining rights for its commercial use may be made to 
NASA, Code AGP, Washington, D.C., 20546. 
Source: Norman M. Garrahan 
(GSFC-285) 
Brief 65-10228	 Category No. 01


Simple circuit produces high-speed, fixed duration pulses

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