A systematic study of the intermediate frequency noise bandwidth of Nb thin-film superconducting hot-electron bolometers is presented. We have measured the spectrum of the output noise as well as the conversion efficiency over a very broad intermediate frequency range (from 0.1 to 7.5 GHz) for devices varying in length from 0.08 μm to 3 μm. Local oscillator and rf signals from 8 to 40 GHz were used. For a device of a given length, the spectrum of the output noise and the conversion efficiency behave similarly for intermediate frequencies less than the gain bandwidth, in accordance with a simple thermal model for both the mixing and thermal fluctuation noise. For higher intermediate frequencies the conversion efficiency decreases; in contrast, the noise decreases but has a second contribution which dominates at higher frequency. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, between 120 and 530 K (double side band).

1.
J.
Kawamura
,
R.
Blundell
,
C. Y.
Tong
,
G.
Gol’tsman
,
E.
Gershenzon
, and
B.
Voronov
,
Appl. Phys. Lett.
70
,
1619
(
1997
).
2.
A.
Skalare
,
W. R.
McGrath
,
B.
Bumble
,
H. G.
LeDuc
,
P. J.
Burke
,
A. A.
Verheijen
,
R. J.
Schoelkopf
, and
D. E.
Prober
,
Appl. Phys. Lett.
68
,
1558
(
1996
).
3.
A.
Skalare
,
W.
McGrath
,
B.
Bumble
, and
H. G.
LeDuc
,
IEEE Trans. Appl. Supercond.
7
,
3568
(
1997
).
4.
B. S.
Karasik
,
M. C.
Gaidis
,
W. R.
McGrath
,
B.
Bumble
, and
H. G.
LeDuc
,
Appl. Phys. Lett.
71
,
1567
(
1997
).
5.
D. E.
Prober
,
Appl. Phys. Lett.
62
,
2119
(
1993
).
6.
P. J.
Burke
,
R. J.
Schoelkopf
,
D. E.
Prober
,
A.
Skalare
,
W. R.
McGrath
,
B.
Bumble
, and
H. G.
LeDuc
,
Appl. Phys. Lett.
68
,
3344
(
1996
).
7.
E.
Gershenzon
,
G.
Gol’tsman
,
I. G.
Gogidze
,
Y. P.
Gusev
,
A. I.
Elant’ev
,
B. S.
Karasik
, and
A.
Semenov
,
Superconductivity
3
,
1582
(
1990
).
8.
B. Karasik and A. Elantev, in Proceedings of the 6th Internation Symposium on Space Terahertz Technology, edited by J. Zmuidzinas and G. Rebiez (CalTech, Pasadena, CA, 1995), pp. 229–246.
9.
B. S.
Karasik
and
A. I.
Elantiev
,
Appl. Phys. Lett.
68
,
853
(
1996
).
10.
F.
Arams
,
C.
Allen
,
B.
Peyton
, and
E.
Sard
,
Proc. IEEE
54
,
612
(
1966
).
11.
H.
Ekström
,
B.
Karasik
,
E.
Kollberg
, and
K.
Yngvesson
,
IEEE Trans. Microwave Theory Tech.
43
,
938
(
1995
).
12.
We neglect here the modification of the thermal time constant, conversion efficiency, and thermal fluctuation noise due to electro-thermal feedback effects. This is justified because the device resistances are all close to the input impedance of the IF amplifier, 50 Ω.
13.
P. J. Burke, Ph.D. thesis, Yale University, 1997 (available from authors).
14.
B.
Karasik
,
K.
Il’in
,
E.
Pechen
, and
S.
Krasnosvobodtsev
,
Appl. Phys. Lett.
68
,
2285
(
1996
).
15.
H.
Ekström
and
B.
Karasik
,
Appl. Phys. Lett.
66
,
3212
(
1995
).
16.
B.
Bumble
and
H. G.
LeDuc
,
IEEE Trans. Appl. Supercond.
7
,
3560
(
1997
).
17.
We have included the effects electro-thermal feedback in the numerical predictions for the output noise and conversion efficiency. The modifications were at most 40%.
18.
P. J. Burke, R. J. Schoelkopf, D. E. Prober, A. Skalare, B. Karasik, M. Gaidis, W. McGrath, B. Bumble, and H. LeDuc (unpublished).
This content is only available via PDF.
You do not currently have access to this content.