A microwave HEMT oscillator with a directly coupled port at 4.2 K

An X-band HEMT oscillator is designed and tested at the cryogenic temperatu re of liquid helium. The designed oscillator has a directly coupled port in addition to an output port to obtain circuit simplicity. For the novel osc illator configuration, an analytic design formula of the feedback network i s derived. The measured data at cryogenic temperature show a significantly improved phase noise and output power compared to the performance of an osc illator operating at room temperature. (C) 2001 John Wiley & Sons, Inc.