The high-speed performance of heterojunction bipolar transistors fabricated by a self-aligned dual-liftoff method is discussed. Transistors with emitter width down to 1. 2 mu m and base doping up to 1 multiplied by 10**2**0/cm**3 have been fabricated. Extrapolated current gain cutoff frequency f//t 67 GHz and maximum frequency of oscillation f//m//a//x of 105 GHz have been obtained. Current-mode logic (CML) ring oscillators with propagation delays as low as 14. 2 ps have been demonstrated. Frequency dividers (1/4) have operated up to 20. 1 GHz.