A superconducting 7.3 GHz two-pole microstrip bandpass filter and a GaAs low noise amplifier (LNA) were combined into an active circuit and characterized at liquid nitrogen temperatures. This superconducting/semiconducting circuit's performance was compared to a gold filter/GaAs LNA hybrid circuit. The superconducting filter/GaAs LNA hybrid circuit showed higher gain and lower noise figure than its gold counterpart

Bhasin, K. B.

Bonetti, R. R.

Chorey, C. M.

Toncich, S. S.

Williams, A. E.

English

NASA Technical Reports Server

NA 4 Technica .Aemorandum 1~5546 
7.573- 
Performance of a Y-Ba-Cu-0 Superconducting 
Filter/GaAs Low Noise Amplifier 
Hybrid Circuit 
K.B. Bhasin and S.S. Toncich 
National Aeronautics and Space Administration 
Lewis Research Center 
Cleveland, Ohio 
C.M. Chorey 
Sverdrup Technology, Inc. 
Lewis Research Center Group 
Brook Park, Ohio 
and 
R.R. Bonetti and A.E. Williams 
COMSA T Laboratories 
Clarksburg, Maryland 
Prepared for the 
1992 IEEE MTT-S International Microwave Symposium 
Albuquerque, New Mexico, June 2 -4, 1992 
https://ntrs.nasa.gov/search.jsp?R=19920012127 2020-03-17T13:28:02+00:00Z
PERFORMANCE OF A Y-Ba-Cu-0 SUPERCONDUCTING FILTEWGaAs 
LOW NOISE AMPLIFIER HYBRID CIRCUIT 
K.B. Bhasin and S.S. Toncich 
National Aeronautics and Space Administration 
Lewis Research Center 
Cleveland, Ohio 44135 
C.M. Chorey 
Sverdrup Technology, Inc. 
Lewis Research Center Group 
Brook Park, Ohio 44142 
R.R. Bonetti and A.E. Williams 
COMSAT Laboratories 
Clarksburg, Maryland 2087 I 
Abstract 
A superconducting 7.3 GHz two-pole microstrip bandpass 
filter and a G a A s  low noise amplifier (LNA) were combined into a 
hybrid circuit and characterized at liquid nitrogen temperatures. 
compared to a gold filter/GaAs LNA hybrid circuit. The super- 
conducting filter/GaAs LNA hybrid circuit showed higher gain and 
lower noise figure than its gold counterpart. 
cn 
\o 
w 
00 
I 
\f This superconducting/semiconducting circuit's performance was 
Introduction 
Before the discovery of high-Tc superconductivity, the inte- 
' gration of low-Tc superconductors with semiconducting devices 
was not feasible since many semiconducting devices freeze-out 
below IO K. The recent demonstration of high-Tc superconducting 
passive microwave components operating at liquid nitrogen tem- 
peratures"* has enhanced the feasibility of integrating these super- 
conducting components with semiconducting devices to achieve 
high performance microwave systems. GaAs and heterostructure 
microwave semiconducting devices make strong candidates for 
integration since they have shown significantly lower noise figures 
at liquid nitrogen temperatures?.' 
In deep. space communications, radio astronomy and radiome- 
fer applications, low noise and low loss requirements are frequently 
met by cooling the microwave components. For the first time we 
have combined in a hybrid circuit a superconducting microstrip 
bandpass filter and a GaAs low noise amplifier (LNA), which is a 
basic building block in these applications. We compared its per- 
formance to a hybrid gold filter/LNA circuit operating at the same 
temperature. The circuit design, fabrication, and experimental 
results are presented below. 
Circuit Design and Fabrication 
A two-pole microstrip bandpass filter was designed with a 
2.5 percent bandwidth, 0.5 dB passband ripple, and 7.5 GHz center 
frequency on lanthanum aluminate substrate. The layout of the 
two-pole filter is shown in Fig. I .  The filter was fabricated using 
laser ablated YBCO superconducting films (-5000 A) on a 10 mil 
lanthanum aluminate substrate. A gold film deposited by E-beam 
evaporation on  the opposite side of lanthanum aluminate substrate 
was used as a ground plane. An identical filter using gold film for 
the microstrip and the ground was also fabricated. 
The LNA selected was an Avantek Inc. PGM 11411 with a 
specified frequency response from 4 to I I GHz, a minimum gain 
of 8.0 dB, and a typical noise figure of 2.5 dB. The bandpass 
filter/GaAs LNA hybrid was mounted in a brass test fixture as 
shown in Fig. 2. The devices were connected by 10 mil gold bond 
wires to 50 C-2 input/output microstrip lines that were fabricated on 
IO mil thick Duroid ( e r  = 2.3) substrate. The length of the micro- 
strip lines were chosen so as to minimize the interaction between 
the launcher pins and the devices. 
The coax to microstrip transition was implemented using 
SMA female flange connectors. Silver paint was used to improve 
the contact between the center conductor of the launcher and the 
microstrip line. 
Cryogenic Measurements and Results 
The LNA and bandpass filters were tested individually to 
verify their performance at T = 300 and 77 K. An HP 8510B 
automatic network analyzer (ANA) was used to measure insertion 
gain or loss, and a HP 8970A noise figure meter was used to 
determine the noise figure of the LNA. Table 1 presents a sum- 
mary of the pertinent results that apply for this work. The data for 
the gold filter shows a reduction in the insertion loss of 1.4 dB 
between T = 300 and 77 K. This is due to lower ohmic loss in the 
gold conductor and to a reduction of loss in the dielectric substrate 
at T = 77 versus 300 K. The HTS filter shows a significantly 
smaller insertion loss than the gold filter at 77 K. This is due to 
the near elimination of conductor loss in the YBCO film compared 
to the loss in the gold conductor. Most of the loss present of the 
HTS filter is due to the use of a gold ground plane. 
The primary advantage in using an HTS filter over a gold fil- 
ter is that the HTS filter offers a much smaller insertion loss. If 
the HTS filter's gold ground plane were replaced with HTS mate- 
rial, a further reduction in insertion loss could be achieved. 
For the LNAhandpass filter hybrid measurements, a fu l l  two 
port calibration was performed inside the cryostat so as to move 
the ANA reference planes to the ends of the semi-rigid cables 
inside the cryostat. Since this experiment is concerned only with 
the relative difference in gain of the hybrid circuit and not with the 
absolute gain, a two port calibration was selected over a TRL or  
LRL calibration, which could move the reference planes of the 
ANA onto the test fixture, thereby removing its effect as well. In 
all measurements performed, only the filters were changed in the 
test fixture. 
To calibrate the noise figure meter, the LNAlbandpass filter 
was replaced in the test fixture by a 50 a thru line supplied by 
Avantek Inc. An ANA measurement was made to determine the 
total insertion loss of the test fixture and semi-rigid cables over the 
frequency range of 7.0 to 8.0 GHz. This loss was found to be 
2.6 dB in this frequency range. One half of this loss (1.3 dB), 
representing the loss of that portion of the test fixture that appears 
at the input of the hybrid, was subtracted away from the noise 
figure measurements that were ma& on the hybrid at the appropri- 
ate frequency points, leaving only the actual noise figure of the 
hybrid. 
Figure 3 shows the difference in the hybrid's gain when gold 
and HTS filters, respectively, are used, while Fig. 4 shows the 
difference in the noise figures. Since the HTS filter becomes func- 
tional only after the system reaches cryogenic temperatures, there 
is no room temperature data provided for it. This particular filter 
was fabricated on a high quality substrate, it began to conduct at 
T = 89 K, and reached its minimum insertion loss at T = 85 K. 
Gaidloss, 
dB 
At 77 K t h e  gold filterLNA hybrid shows a noise figure 
improvement of nearly 3.5 dB as  compared to 300 K, while the 
HTS filter/LNA hybrid shows a 5.5 d B  improvement in noise fig- 
ure compared to gold at 300 K. As expected, the overall gain of 
the HTS filter/LNA hybrid is greater than that of the gold hybrid 
due to a lower insertion loss of the HTS filter. 
Noise figure, 
dB 
As a check on the accuracy of these results, the data obtained 
for the LNA and filters individually is inserted in the expression 
for the noise figure of a cascade, F, = F, + ( F 2  - l)/G,. Here, 
F ,  and F2 are the noise figures of the filter and LNA respectively. 
and G, is the loss of the filter. Table 2 shows the results for the 
minimum noise figure of the hybrid. There is good agreement 
between the calculated and measured noise figures for the hybrid. 
Gold filter T = 3 0 0 K  
T = 7 7 K  
HTS filter T = 7 7 K  
Conclusions 
-4.2 4.2 
-2.8 2.8 
-0.5 0.5 
A low loss two-pole Y-Ba-Cu-0 superconducting bandpass 
filter on lanthanum aluminate substrate was connected in series 
with a packaged GaAs low noise amplifier and fully characterized 
at 77 K. The noise figure characteristics of the superconducting 
filter/LNA hybrid circuit when compared to the gold filter/LNA 
hybrid circuit showed an improvement of 2. I dB at 77 K. The 
gain characteristics showed an improvement of 0.5 dB for the HTS 
filter hybrid over the gold hybrid at 77 K. 
This first demonstration of superconducting filtedGaAs LNA 
hybrid circuit shows potential for applications in radio astronomy, 
radiometers and deep space communications syslems where high 
performance is desircd in spite of the cooling requirements. 
Ac know ledgment 
The authors wish to acknowledge the assistance of 
Mr. Ed Rylander, Sr. Test Engineer at Avantek Inc., Folsom, CA 
for his useful discussions on noise figure measurement and for 
supplying us with Avantek thru lines for calibration purposes. 
References 
I .  IEEE Trans. Microwave Theory Tech., vol. 3Y. no. 9, 1991 
(entire issue). 
2. D.C. Webb and M. Nisenoff, "The high temperature supercon- 
ductivity space experiment," Microwave J., vol. 34, pp. 85-9 1, 
1991. 
3. M.W. Pospieszalski, S. Weinreb, R.D. Norrod, and R. Harris, 
"FET's and HEMT's at cryogenic temperatures-their proper- 
ties and use in low-noise amplifiers," IEEE Trans. Microwave 
Theory Tech., vol. 36, pp. 552-560, 1988. 
4. S. Weinreb, "Low-noise, cooled GASFET amplifiers." 
Trans. Microwave Theory Tech., vol. 28, pp. 1041-1054, 
1980. 
TABLE I.-DATA ON THE LNA AND BANDPASS FILTERS 
USED IN THIS EXPERIMENT 
2 3  1 0.9 I LNA (PGM 11421) 
2 
Calculated 
noise figure. 
dB 
6.7 
3.7 
I .4 
Gold filter/LNA. T = 300 K 
Gold filter/LNA, T = 77 K 
HTS filter/LNA, T = 77 K 
.- 
80 pm 
Measured 
noise figure, 
dB 
7 0  
3.6 
I .s 
75 Wm r 
Figure 1 .-Layout of the C-band, two pole bandbass filter. 
Two pole HTS filter 
/ 
/ 
LNA 
out In 
c-91-06409 
Figure 2.-Test fixture used for measurements on bandpass 
filter/LNA hybrid. 
c b  
10 r-- I a 1  
a 3.42 d 0  at 7.345 GHz 
b 5.3 dB at 7.415 GHz 
c 5.82 dB at 7.175 GHz 
-30 
6.5 7.5 0.5 
Frequency, GHz 
Figure 3.-Forward transmission (gain) of the gold filter/LNA 
hybrid (a) at T = 300 K, (b) at T = 77 K, and (c) the HTS filter/ 
LNA hybrid at T = 77 K. 
m 
73 
14.0 r 
I I 
7.1 7.2 7.3 7.4 7.5 7.6 
Frequency, GHz 
(a) Gold filter/LNA hybrid. 
L 
6'o r 0 T = 7 7 K  
0 
7.0 7.1 7.2 7.3 7.4 7.5 
Frequency, GHz 
(b) HTS filter/LNA hybrid. 
Figure 4 . 4 o i s e  figure measurement as a function of temper - 
ature. 
ORIGINAL PAC& 
BLACK AND WHiTE PHOTOGRAPH 
3 
REPORT DOCUMENTATION PAGE 
Performance of a Y-Ba-Cu-0 Superconducting Filter/GaAs 
Low Noise Amplifier Hybrid Circuit 
Form Approved 
OMB NO. 0704-0188 
WU-506-72- 1B 
5. AUTHOR(S) 
I. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 
1992 
3. REPORT TYPE AND DATES COVERED 
Technical Memorandum 
National Aeronautics and Space Administration 
Washington, D.C. 20546-0001 
1. TITLE AND SUBTITLE 
NASA TM- 105546 
5. FUNDING NUMBERS 
K.B. Bhasin, S.S. Toncich, C.M. Chorey, R.R. Bonetti, andA.E. Williams 
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 
National Aeronautics and Space Administration 
Cleveland, Ohio 44135 -3191 
Lewis Research Center 
9. SPONSORING/MONITORING AGENCY NAMES(S) AND ADDRESS(ES) 
I 
13. ABSTRACT (Maximum 200 words) 
A superconducting 7.3 GHz two-pole microstrip bandpass filter and a GaAs low noise amplifier (LNA) were com- 
bined into a hybrid circuit and characterized at liquid nitrogen temperatures. This superconductinglsemiconducting 
circuit’s performance was compared to a gold filter/GaAs LNA hybrid circuit. The superconducting filter/GaAs LNA 
hybrid circuit showed higher gain and lower noise figure than its gold counterpart. 
8. PERFORMING ORGANIZATION 
REPORT NUMBER 
E - 6869 
10. SPONSORING/MONITORING 
AGENCY REPORT NUMBER 
15. NUMBER OF PAGES 
A 14. SUBJECT TERMS 
12a. DISTRIBUTION/AVAILABlLlTY STATEMENT 
GaAs circuit; Cryogenic electronics; HTS 
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OF REPORT OF THIS PAGE OF ABSTRACT 
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Performance of a Y-Ba-Cu-O superconducting filter/GaAs low noise amplifier hybrid circuit

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