RF noise in 0.18-μm and 0.13-μm MOSFETs

Studied the gate finger number and gate length dependence on minimum noise figure (NF_min) in deep submicrometer MOSFETs. A lowest NF_min of 0.93 dB is measured in 0.18-μm MOSFET at 5.8 GHz as increasing finger number to 50 fingers, but increases abnormally when above 50. The scaling gate length to 0.13 μm shows larger NFmin than the 0.18-μm case at the same finger number. From the analysis of a well-calibrated device model, the abnormal finger number dependence is due to the combined effect of reducing gate resistance and increasing substrate loss as increasing finger number. The scaling to 0.13-μm MOSFET gives higher NF_min due to the higher gate resistance and a modified T-gate structure proposed to optimize the NF_min for further scaling down of the MOSFET.