2-bit adder: carry and sum logic circuits at 19 GHz clock frequency in InAlAs/InGaAs HBT technology

Carry and sum circuits for a 2-bit adder used in a pipelined 2N-bit adder-a ccumulator architecture are reported. To obtain high clock rates in a desig n with multiple gate delays a novel merged AND-OR-Latch structure using fou r-level series gated current steering logic is employed. These integrated c ircuits were fabricated in InAlAs/InGaAs transferred substrate heterojuncti on bipolar transistor technology and operate up to 19GHz clock rate.