High-performance AlInAs/GaInAs/InP DHBT X-band power cell with InP emitter ballast resistor

We report for the first time large-signal performance of a multi-finger AlInAs/GaInAs/InP DHBT power cell with epitaxial InP emitter ballast resistors. The region of safe operation is extended using epitaxial InP emitter resistor structures. The thermal stability of power cells with this structure is increased compared with devices with similar layer structures but without the ballast epi-resistors. The power cell consists of ten 2-μm×30-μm emitter fingers. Under DC bias, the device is unconditionally stable up to J_c=5×10⁴ Acm^-2 at V_ce=6 V, and the upper range of bias is limited by burn-out (on unthinned wafer) rather than by current hogging. An output power of 1.6 W, corresponding to a high power density of 5.3 W/mm, and a power-added efficiency of 62% were measured on wafer at 9 GHz at V_cc=12 V under class B CW operation. The output power can be increased at the expense of PAE. At a PAE of 54%, an output power of 1.9 W, corresponding to an impressive power density of 6.3 W/mm is obtained