RF characteristics in a multi-finger structure for 70-nm CMOS devices at low temperature

The RF characteristics of various multi-finger 70-nm CMOS devices were measured and analyzed at low temperature. Significant improvement in DC and RF performance were observed at cryogenic temperatures. In addition, current gain cutoff frequency and maximum oscillation frequency properties were analyzed in terms of gate layout. Current gain cutoff frequency was found to be maximized with a small number of fingers. It was also found that maximum oscillation frequency strongly depends on the gate resistance. Results show that an optimized design of the unit finger width is necessary for RF MOSFETs to achieve high frequency performance.