A Compact D-band 32-Way 28.2 dBm Power Amplifier in InP HBT

This paper presents a 32-way D-band power amplifier in Teledyne’s 250-nm InP HBT. A 2-finger common-emitter HBT was chosen as a unit cell. It provides a more uniform heating profile and a lower junction temperature than a 4-finger cell. Its thermal resistance is lower than a common-base cell, reducing the risk of thermal runaway and current hogging. RF lines and bias distribution networks are isolated vertically by a common ground plane, and can be independently layout on the same area. This enables a compact layout and strictly symmetric bias distribution, minimizing thermal gradients across unit cells. S-parameter testing shows 27.7 dB peak S21 at 134 GHz with 28 GHz 3-dB bandwidth. Large-signal measurement reveals 26.1-28.2 dBm PSAT and 9.6-17.5 % PAE for 126-158 GHz, with 0.26 W/mm2 power density. To the authors’ knowledge, this represents the highest output power and power density for a D-band power amplifier in any technology.