High-speed, high-resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) are key components for advanced digital receivers and high-speed instruments. Several multi-gigasample per second ADCs and DACs have been developed in a production AlGaAs/GaAs heterojunction bipolar transistor (HBT) technology. In particular, a 10-bit ADC showed 8 ENOBs and >65 dB spur-free-dynamic-range (SFDR) for a 49 MHz input signal when sampling at 500 MHz; an 8-bit, 3 GS/s ADC showed 6.5 effective-number-of-bits (ENOBs when sampling at 2 GS/s under Nyquist input condition; a 2 GS/s DAC showed >60 dB SFDR when sampling at 1 GHz and synthesizing up to 400-MHz output.