Amplifier, fabricated on single dielectric substrate, has pair of Schottky barrier varactor diodes mounted on single semiconductor chip. Circuit includes microstrip transmission line and slot line section to conduct signals. Main features of amplifier are reduced noise output and low production cost

Dickens, L. E.

English

NASA Technical Reports Server

June 1975	 B75-10102 
•	 NASA TECH BRIEF 
Marshall Space Flight Center 
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. 
Integrated-Circuit Balanced Parametric Amplifier 
A new balanced parametric amplifier has been 
fabricated on a single dielectric substrate. The 
amplifier has a pair of Shottky barrier varactor diodes 
mounted on a single semiconductor chip. The circuit 
includes a microstrip transmission line and a slot line 
section to conduct the signals. The main features of 
the amplifier are reduced noise output and low 
production cost. 
As shown in Figure 1, the amplifier circuit is built 
on a dielectric substrate which supports the microstrip 
line on one side and the slot line section on the other 
side. The microstrip line extends from the edge of the 
substrate to the slot line section. They are joined by a 
metallization feedth rough element penetrating 
through the substrate. 
A single semiconductor chip, as shown in the 
enlarged view in Figure 2, contains a pair of Schottky 
barrier varactor diodes. One terminal of each diode is 
attached to the feedthrough element. The remaining 
terminal of each diode forms an inductive connection 
attached to a metallized film. The film covers one side 
Microstrip Line 
First	 Second	 Third 
Section I Section	 I Section
of the substrate. Lengths L of the slot line sections are 
chosen to resonate the varactor diodes at idler 
frequency. Lengths of inductive connections are also 
selected to series-resonate the diodes at pump 
frequency. 
The pump frequency is supplied by a waveguide 
(not shown) which transmits through a filter element 
to a reduced waveguide section. This section is 
dimensioned so that its length corresponds to 2q14 and 
A/2 simultaneously (A = idler signal wavelength, and 
Ap = pump signal wavelength). The filter element is 
parallel-resonant at the pump frequency but repre-
sents a very low impedance at the idler frequency. 
This low impedance at the idler frequency is 
transformed through the reduced waveguide section 
to a very high impedance at the slot line section, which 
effectively isolates the idler circuit from the pump 
circuit. 
The microstrip line includes three sections. The 
first section is adapted to be coupled to an external 
circuit such as a circulator (not shown). The section 
Feedthrough 
Element 
S
-S 
High-
owl	 nA	
Impedance 
Line 
Section 
Substrate
Figure 1. Amplifier Mounted on Substrate
(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=19750000102 2020-03-19T20:06:40+00:00Z
S 
High-Impedance	 Inductive 
--	
Line Section	
rr/C0nntion 
-	
Semiconductor 
L-----------Chip 
Element 
Varactor 
-	 -	
Feedthrough 
Diodes
Inductive 
Connection 
L_______  L 
Metallized
Film 
Figure 2. Slot Line Section (Opposite Side of Figure 1)
Slot 
Portion 
couples into a second line section of a length 
substantially equal to a quarter wavelength of the 
input and output signals (A/4). Following the second 
section is a wide third line section of a relatively longer 
length equal to multiple half wavelengths of the input 
and output signals, i.e., nA5/2, where n is an integer. 
In operation, the RF signal to be amplified is fed 
through the microstrip circuitry to the varactor 
diodes. Pump power is supplied by the waveguide as 
described, which causes a flow of electrical charge 
within the varactor diodes at the pump frequency. 
The interaction of the input signal current and the 
pump current, coupled by the voltage-dependent 
capacitance of the varactor diodes, causes the 
varactors to exhibit a negative resistive impedance to 
the input signal. This amplifies the input signal which 
is reflected back through the microstrip line for 
transmittal to an external circuit. The balanced diode 
connection prevents the transmission of pump or idler 
energy into the microstrip circuitry.
Note: 
Requests for further information may be directed 
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
Patent Counsel 
Marshall Space Flight Center 
Code CCO1 
Marshall Space Flight Center, Alabama 35812 
Source: L. E. Dickens of
Westinghouse Electric Corp.

under contract to

Marshall Space Flight Center

(MFS-23193) 
to: Technology Utilization Officer
	 5 
Marshall Space Flight Center 
Code- ATO1 
Marshall Space Flight Center, Alabama 35812 
Reference: B75.10102 
Categories: 01 (Electronics - Components 
and Circuitry) 
B75-10102	 02 (Electronics Systems)


Integrated-circuit balanced parametric amplifier

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