SiGe HBT-Based Active Cold Load for Radiometer Calibration

摘要

An active cold load (ACL) using SiGe heterojunction bipolar transistor (HBT) has been realized at L-band for radiometer calibration. A hybrid circuit has been realized with a discrete transistor, lumped elements and microstrip transmission lines. The ACL exhibits return loss higher than 30 dB and a noise temperature less than 65 K in the L- band (1400-1427 MHz). The ambient temperature sensitivity is less than 0.3 K/°C.