Long-term stability of an SiGe HBT-based active cold load

In this study, results of long-term stability of an Active Cold Load (ACL), realized at L-band with an SiGe heterojunction bipolar transistor are reported. The ACL exhibits return loss higher than 35 dB and a noise temperature less than 66 K. A noise injection radiometer has been developed to perform the measurements. A noise-equivalent delta temperature of less than 31 mK and a stability estimated to 25 mK during 95 s were obtained from Allan variance analysis. The long-term stability measurements performed over 4 months, indicate that a maximum deviation less than 0.35 K on the noise temperature is obtained with this ACL.

[1]  R. L. Forward,et al.  Electronically Cold Microwave Artificial Resistors , 1983 .

[2]  S.M. Lardizabal,et al.  Design and characterization of MMIC active cold loads , 2000, 2000 IEEE Radio Frequency Integrated Circuits (RFIC) Symposium Digest of Papers (Cat. No.00CH37096).

[3]  A. Fejzuli,et al.  Design and characterization of FET based cold/hot noise sources , 1997, 1997 IEEE MTT-S International Microwave Symposium Digest.

[4]  James B. Mead,et al.  Two-load radiometer precision and accuracy , 2006, IEEE Transactions on Geoscience and Remote Sensing.

[5]  Yann Kerr,et al.  Design and test of the ground-based L-band Radiometer for Estimating Water In Soils (LEWIS) , 2004, IEEE Transactions on Geoscience and Remote Sensing.

[6]  Andreas Colliander,et al.  Improved receiver architecture for future L-band radiometer missions , 2007, 2007 IEEE International Geoscience and Remote Sensing Symposium.

[7]  Laurent Escotte,et al.  Stability Analysis of an SiGe HBT-Based Active Cold Load , 2011, IEEE Transactions on Microwave Theory and Techniques.

[8]  Niels Skou,et al.  Measurements on Active Cold Loads for Radiometer Calibration , 2008, IEEE Transactions on Geoscience and Remote Sensing.

[9]  L. Escotte,et al.  SiGe HBT-Based Active Cold Load for Radiometer Calibration , 2010, IEEE Microwave and Wireless Components Letters.

[10]  Adriano Camps,et al.  The determination of surface salinity with the European SMOS space mission , 2004, IEEE Transactions on Geoscience and Remote Sensing.

[11]  R. Frater,et al.  An Active "Cold" Noise Source , 1981 .