Ultra-high-speed ring oscillators based on self-aligned-gate modulation-doped n(+)-(Al,Ga)As/GaAs FETs

Ultra-high-speed ring oscillator test circuits based on modulation-doped n(+)-(Al,Ga)As/GaAs field-effect transistors have been fabricated using a completely planar self-aligned gate by an ion-implantation process. A gate propagation delay of 11.6 ps/gate at a power dissipation of 1.56 mW/gate was measured at room temperature. On cooling to 77 K the gate delay decreased to 8.5 ps/gate at a power dissipation of 2.59 mW/gate. These ring oscillator gate delay times are the fastest ever reported for any semiconductor digital circuit technology.