Calibration of a Digital Correlator for Noise-Parameter Measurements

A new digital correlator measuring noise parameters of amplifiers and transistors based on a wave model was recently developed. Accurate noise parameter extraction from the device under test (DUT) required a carefully designed calibration procedure to account for non-ideal system factors such as asymmetry and channel phase deviation. In this paper, we evaluate two complementary and rigorous calibration methods: one utilizing a noise diode input and the other employing swept continuous-wave (CW) tones. We compared the advantages and disadvantages of these two methods, demonstrating their respective strengths. The extracted gains and phase delay, obtained through postdigital signal processing (DSP), showed consistent results between two calibration techniques. This consistency indicated that our calibration procedure was reliable and our noise-measurement system was stable.