This decade will be very important for cosmology due to several missions to measure the cosmic microwave background radiation. These measurements require highly sensitive radiometers operating over a very wide frequency spectrum. The millimeter wave radiometers are best developed as pseudo correlating radiometers due to the inherent stability and high sensitivity of this instrument, To miniaturize the size and power consumption of these radiometers we have developed the critical low noise amplifier and phase switch MMICs using high-performance InP technologies. The low noise amplifiers achieved record 2.3 dB noise figure over the 60-80 GHz frequency band at room temperature and less than 25 K noise temperature at 20 K ambient temperature. These MMICs form the building blocks for 70 GHz highly sensitive correlating radiometers, that are needed e.g. in the ESA Planck mission

Cong, T. L.

Dawson, D.

Gaier, T.

Hughes, N. J.

Jukkala, P.

Kangaslahti, P.

Karttaavi, T.

Lahdes, M.

Sjöman, P.

Tuovinen, J.

Weinreb, S.

Tuovinen, Jussi

Karttaavi, Timo

Lahdes, Manu

Hughes, N.

Cong, T.

Weinreb, W.

VTT Research System

Low noise amplifiers in InP technology for pseudo correlating millimeter wave radiometer

Caltech Authors - Main

TH4C-2 
Low Noise Amplifiers in InP Technology for Pseudo Correlating 
Millimeter Wave Radiometer 
P. Kangaslahti’*’, T. Gaier4, D. Dawson4, J. Tuovinen3, T. Karttaavi3, M. Lahdes3, N.J. Hughes’, T.L. 
Cong2, P. Jukkala’, P. Sjoman’ and S. Weinreb4 
‘Electronic Circuit Design Laboratory, Institute of Digital Communications, Helsinki University of 
Technology, Finland, 2Ylinen Electronics Ltd., Kauniainen, Finland, 3MilliLab, VTT Information 
Technology, Espoo, Finland, 4Jet Propulsion Laboratory, Pasadena, CA, USA, ’Metsahovi Radio 
Observatory, Kirkkonummi, Finland 
Abstract This decade will be very important for 
cosmology due to several missions to measure the cosmic 
microwave background radiation. These measurements 
require highly sensitive radiometers operating over a very 
wide frequency spectrum. The millimeter wave radiometers 
are best developed as pseudo correlating radiometers due to 
the inherent stability and high sensivity of this instrument. 
To miniaturize the size and power consumption of these 
radiometers we have developed the critical low noise 
amplifier and phase switch MMICs using high-performance 
InP technologies. The low noise amplifiers achieved record 
2.3 dB noise figure over the 60-80GHz frequency band at 
room temperature and less than 25 K noise temperature at 
20 K ambient temperature. These MMICs form the building 
blocks for 70GHz highly sensitive correlating radiometers, 
that are needed e.g. in the ESA Planck mission 
~.INTRODUCTION 
The current decade will shed light to many of the 
fimdamental problems of cosmology by measurements of 
the properties of the Cosmic Microwave Background 
(CMB). These CMB measurements require radiometric 
receivers with unprecedented stability and cryogenic noise 
temperature to obtain the required sensitivity. Several 
space missions to map the CMB are under operation or 
planning; COBE was the first of these (launched in 1989), 
it will be succeeded by Microwave Anisotropy Probe 
(MAP) within the first half of this decade and during the 
the second half of this decade by Planck. For these 
missions the development of InP HEMT technology has 
been of uttermost importance. Improvements in the HEMT 
device performance and integrated circuit processing yield 
and reliability enable the design of ever more complex 
instruments with large numbers of detectors. The COBE 
and MAP missions used discreet InP HEMT devices in the 
LNAs of the radiometers, however, the goal in hture 
missions, such as Planck, is to use InP MMIC technology. 
This study aims to address the development of InP 
MMIC LNAs for use in 60-80 GHz pseudo-correlating 
radiometer. The objectives of this paper are as follows: to 
demonstrate optimum microstrip and CPW LNA designs 
for minimum noise; to present design of these LNAs for 
gain and phase match between individual devices; and to 
present the design of these LNAs in minimum size to 
enable assembly of the MMICs in resonant free cavities.. 
Finally, the operation of the developed low noise amplifier 
MMICs are demonstrated in a 60-80GHz pseudo 
correlating radiometer. 
11. DESIGN OF Low NOISE AMPLIFIERS 
Low noise amplifiers are key components in the 
development of low noise receivers. The successfbl design 
of LNAs is possible only with high performance foundry 
processes. For this work we used the state-of-the-art InP 
process of TRW[l]. This process features O.1pm 
gate-length, very high device transconductance above 
1000mS/mm, cutoff ffequencies above 200 GHz, thin film 
capacitors and resistors. The 75pm substrate enables both 
grounded CPW and microstrip design. This process has 
been used to develop 3dB noise figure broadband LNAs 
for W-band[2]. 
InP HEMT modeling is an important part of LNA 
development. Device models used in this work were based 
on hot and cold measurements of HEMTS[2] and on-wafer 
noise parameter measurements at 50-75GHz. These __ 
measurements were used to extract a Pospieszalski noise 
model [3]. 
The design of the LNAs incorporated four-stages of 
amplification. Each stage had an optimum size device to 
match the devices to noise minimum in each interstage 
matching network. The gain match was improved by using 
source inductance in each stage and employing thin-film 
50Q resistors in the gates of second to fourth stage. The 
layout of the CPW LNA is shown in Figure 1 and the 
E 
1959 
0-7803-6538-0/01/$10.00  2001 IEEE 2001 IEEE MTT-S Digest 
microstrip LNA in Figure 2. The compact size of the 
designs make them inherently broadband, due to the short 
electrical distance between the amplification stages and, 
most importantly, reduced number of matching elements. 
The broadband nature of the LNAs and low number of 
matching networks improve also the phase matching 
between individual LNAs. 
III.EXPERIMENTAL RESULTS 
The developed LNAs were measured on-wafer. Figure 3 
shows the results of a typical microstrip LNA 
performance. These LNAs have the required flat gain and 
noise figure across the 60-8OGHz frequency band. The 
CPW design measurement results (Fig. 4) indicate nearly 
similar results. The gain has some roll-off at the higher 
end of the frequency band, although not clearly visible in 
Figure 4. The CPW design noise figure is a few tenths of 
degree higher, potentially due to the inherent higher losses 
in CPW transmission lines than in microstrips. 
These LNAs were mounted in packages that had WR-15 
input and output ’ waveguides. CPW to waveguide 
transitions on 100 pm alumina substrate were designed 
using FDTD electromagnetic simulations. These 
transitions were based on previous designs at W-band [4]. 
Figure 5 shows cjogenic noise of less than 25K over a 
narrow band and in a second amplifier, 35K over the 
desired frequency band. The transitions needed tuning 
with bonding wires to achieve these results and we expect 
to obtain broadband noise temperature of less than 30K 
with a redesign of the transitions. 
IVMEASUREMENTS IN A PSEUDO CORRELATING RADIOMETER 
Packaged LNAs were selected for best gain and phase 
match to realize the pseudo correlation radiometer. It is 
important to have very good balance between the two legs 
of the radiometer to obtain sufficient isolation between the 
source and the reference signals. Figure 6 shows the 
measured isolation between the two legs of the radiometer 
in room temperature. This radiometer has now been 
installed in a cryogenic chamber for measurements in 20K 
ambient temperature. Figure 7 shows the cryogenic 
chamber assembly and topology diagram. 
V. CONCLUSION 
We have demonstrated the design of very low noise, 
broadband InP MMIC LNAs using microstrip 
transmission lines and in a separate design, grounded 
CPW lines. These LNAs provided 2.3dB noise figure and 
24-27dB gain over a very broad frequency bandwidth. 
When cooled to 20 K, the LNAs had less than 25K noise 
temperature. These properties were critical in the 
realization of the pseudo correlation radiometer 
breadboard that demonstrated sufficient isolation and low 
noise performance at room temperature. The radiometer 
breadboard is currently in cryogenic testing. 
VI. ACKNOWLEDGEMENT 
This study was supported by the Academy of Finland, 
National Technology Agency, TEKES, Finland and Jl’L 
CHOP-programme. We would also like to thank R. Lai at 
TRW Space and Communications for the processing of 
these circuits. 
VI1 . REFERENCES 
R.Lai, et al, “An Id’ HEMT MMIC LNA with 
7.2dB gain at 190 GHz”, IEEE MGWL, pp. 
393-395, vol. 8, no. 11, Nov. 1998. 
S .  Weinreb, R. Lai, N. Erickson, T. Gaier, and J. 
Wielgus, “ W-Band InP Wideband MMIC LNA with 
30K Noise Temperature”, IEEE Microwave Theory 
and Techniques Symposium Digest, Anaheim, CA, 
June 1999, pp. 101-104. 
M. Pospieszalski, “A Modeling of Noise Parameters 
of MESFETs and MODFETs and Their Frequency 
and Temperature Dependence”, IEEE Trans. on 
Microwave Theory and Techniques, vol. MTT-37, 
Y.-C. Leong and S .  Weinreb, “Full Band 
Waveguide-to-Microstrip Probe Transitions”, IEEE 
Microwave Theory and Techniques Symposium 
Digest, Anaheim, CA, June 1999, pp. 1435-1438. 
pp. 1340-1350, 1989. 
Figure 1. Layout of the microstrip LNA. Chip size is 
2.1x0.8mm2. 
1960 
Figure 2. Layout of the CPW LNA. Chip size is 
2.1x0.8mm2. 
5 -  
25 
*Gain 
+NF - 1  
0 1  L O  
50 55 60 65 70 75 
Frequency [Gk] 
Figure 3. Measured gain and noise figure of the microstrip 
LNA. The gain is 24 to 27dB and noise figure 2.3 dB in 
the frequency range 60-8OGHz. The MMIC is biased to 
Vd=0.7V, Id=28mA 
T 7  
35 ,-- __ 
30 
25 
m" 20 9 
.: 15 
8 
10 
4- t 
6 
5 
4g 
3 %  
2 
Figure 4. Measured gain and noise figure of the grounded 
CPW LNA. The gain is 23 to 26dB and noise figure 2.5 
dB in the fiequency range 60-80GHz. The MMIC is biased 
to Vd=O.7V, Id=28mA 
+Gain AMP1 -4- Gain AMP2 
+Tn AMP1 +Tn AMP2 
30 100 
27 90 
24 80 
21 70 - ig 18 60 p 
15 50 f: 
*ii 12 40 
O 9  30 
6 20 
3 10 
0 0 
60 65 70 75 80 
Frequency [GHz] 
Figure 5. Measured gain and noise temperature of two 
packaged LNAs at 20K ambient temperature. The gain is 
24 to 27dJ3 and noise temperature is less than 25K from 73 
to 77GHz. In the frequency range 60-80GHz the noise 
temperature is 35K. The LNAs are biased to Vd=O.8V, 
Id=8mA. 
' I '  ~. 
Figure 6. Measured isolation between the legs of the 
radiometer. The scale is 5dE3 per division and frequency 
range is 50 to 75GHz. The radiometer has 20dB isolation 
between the signal and the reference. The room 
temperature noise temperature of the radiometer is 
Tn=430K. The frequency band of the radiometer is limited 
to 65-80GHz by a bandpass filter. 
1961 
Signal 
R d  
c 
switch 
Detected 
SignaVRef 
M c t c d  
RdlSignal 
Figure 7. In the photograph the radiometer is shown 
assembled in a cryostat. The topology of the radiometer is 
described in the schematic diagram. 
1962 


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Low noise amplifiers in InP technology for pseudo correlating millimeter wave radiometer

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