HIGH-SPEED STATIC FREQUENCY DIVIDER EMPLOYING N** plus -GE GATE ALGAAS/GAAS MISFETS.

The high-speed potential of n** plus -Ge gate AlGaAs/GaAs MISFETs has been demonstrated by fabricating a divide-by-four static frequency divider. The transconductance of a MISFET with 0. 6- mu m gate length was 470 mS/mm. The small V//t//h standard deviation of 13 mV throughout the 2-in wafer confirms the principal advantage of the MISFET, namely high V//t//h uniformity. The frequency-divider circuit was based on source-coupled FET logic with 0. 9- mu m gate-length MISFET. A maximum toggle frequency as high as 16 GHz with a power dissipation of 36 mW per T-flip-flop has been achieved at room temperature. In addition, a cutoff frequency as high as 54 GHz has been achieved in a 0. 5 mu m gate length MISFET, which leads to an electron velocity in the channel as high as 1. 7 multiplied by 10**7 cm/s.