Development of varactor diode assembly overcomes parasitic reactances of conventional varactor packages. In specially constructed assembly very high idler-frequency to signal-frequency ratios are used to obtain low-noise operation over maximum bandwidth

Dickens, L. E.

English

NASA Technical Reports Server

Flat Metal Wafer
Screw-
Adjustable 
Capacitive 
Obstacle
Adhesive 
and Seal 
Material 
Quartz 
Insulating 
Spacer 
.
Waveguide 
Opening
April 1975	 B75-10031 
NASA TECH BRIEF 
Goddard Space Flight Center 	
A 
NASA Tech Briefs announce new 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. 
Varactor Diode Assembly With Low Parasitic Reactances 
Parametric amplifiers have been in use for a 
number of years for low-noise amplification of 
microwave signals. They are still undergoing im-
provements which can yield lower noise and wider 
band operation. 
One recent improvement is the development of the 
varactor diode assembly shown in the figure. It 
overcomes the parasitic reactances of conventional 
varactor packages. In this specially constructed
assembly very high idler-frequency to signal-
frequency ratios are used to obtain low-noise 
operation over a maximum bandwidth. The idler 
energy is restricd to the vicinity of the metal wafer 
holder used for mounting a pair of semiconductor 
chips. The dimensions of the diode contact wires and 
the diode junction capacitances are such that resonant 
frequencies are greater than are possible with 
conventional diodes. 
Diode Contact Pin Fixed 
Capacitive	
I Obstacle \ 
Semiconductor 
Diode Pair
Whisker 
Contact 
Whisker 
Carrier 
.
Varactor Diode Assembly
(continued overleaf) 
This document was prepared underthe 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=19750000031 2020-03-19T20:03:07+00:00Z
n 
Im
The enlarged area of the figure shows a pair of 
semiconductor chips mounted on a contact pin. 
Contact is established through a pair of low-
inductance wire whiskers that are positioned by 
whisker carriers. An insulating quartz spacer, which 
is solidly affixed by adhesive and sealer material, 
'positions the contact pin assembly. The two diodes 
provide a balanced arrangement and geometrically 
isolate the idler and the fundamental pump energies 
from the signal circuit. 
The idler tuner consists of the waveguide section, 
the fixed capacitive obstacle, and the screw-adjustable 
capacitive obstacle. These elements restrict the major 
part of the circulating idler current to the immediate 
vicinity of the diodes. 
Each wafer has its own adjustable idler resonator; 
this is a key feature in the attainment of both 
low-noise operation and broad bandwidth. The diode 
is reactance matched at the signal frequency which 
effectively presents the negative of the average 
junction reactance to the junction point of the two 
diodes. This arrangement also efficiently couples 
energy to and from the diode without affecting the 
idler ctIrrent.	 -
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Goddard Space Flight Center 
Code 704.1 
Greenbelt, Maryland 20771 
Reference: TSP75-10031 
Patent status: 
This invention has been patented by NASA (U.S. 
Patent No. 3,833,857). Inquiries concerning non-
exclusive or exclusive license for its commercial 
development should be addressed to: 
Patent Counsel 
Goddard Space Flight Center 
Code 204 
Greenbelt, Maryland 20771 
Source: Lawrence E. Dickens of 
Westinghouse Electric Corp.
under contract to
Goddard Space Flight Center 
(GSC- 11617) is 
Categories: 01 (Electronics - Components and 
Circuitry) 
B75-10031
	 02 (Electronics Systems)


Varactor diode assembly with low parasitic reactances

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server