Towards VLSI GaAs heterostructure FET integrated circuits

A self-aligned, refractory metal gate, heterostructure FET process for the fabrication of high-speed digital and mixed digital/analog LSI/VLSI integrated circuits is reported. A 4500-gate 16*16 complex multiplier, a 3800-gate butterfly adder and a four-bit analog-to-digital converter have been demonstrated using MBE (molecular beam epitaxy)-grown heterostructure FET technology. With nominal 1- mu m-gate-length devices, DCFL (direct-coupled FET logic) ring oscillators have propagation delays, of 28 ps/stage at a power dissipation of 1 mW/stage. When the gate length is reduced to 0.5 mu m, DCFL ring oscillators have propagation delays of 17 ps/stage with a power dissipation of 1 mW/stage.<>