This paper describes a novel logic approach, diode-HBT logic (DHL), that is implemented with GaAlAs/GaAs HBT's and Schottky diodes to provide high-density and low-power digital circuit operation. This logic family has been realized with the same technology used to produce ECL/CML circuits. We have demonstrated the logic operation with a 19-stage ring oscillator and a frequency divider. A gate delay of 160 ps was measured with 1.1 mW of power per gate. The divider worked properly up to 6 GHz. Layouts of a DHL flip-flop and divider have shown that circuit area and transistor count can be reduced by about a factor of 3, relative to ECL/CML circuits. The new logic approach allows monolithic integration of highspeed ECL/CML circuits with high-density DHL circuits.