A GaAs Low Power Normally-on 4-bit Ripple Carry Adder

A GaAs low power Buffered FET Logic (BFL) 4-bit ripple carry adder is presented. Preliminary performance measurements indicate a critical path average propagation delay of 1.9 ns at a total power dissipation of 45 mW, output buffers included. This corresponds to an average propagation delay of 380 ps/gate (FI/ FO = 5/3), an average power consumption of 1.5 mW/gate, and a power-delay product of 0.6 pJ. Unwired circuit density is 300 gates/mm² while the effective density is 200 gates/mm².