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We report the first large-signal power result from a double heterojunction bipolar transistor (DHBT) based on the GaInP/GaAs/GaInP material system. A CW output power of 1.51 W and a power added efficiency of 52% were achieved at 3 GHz. Because the GaInP collector has a relatively high bandgap of 1.89 eV, high dc bias voltage operation with collector bias extending to 20 V (for a 40-V swing) is possible in this GaInP/GaAs/GaInP DHBT. This high dc bias voltage operation represents a unique advantage over the more conventional AIGaAdGaAs HBT. AINP/GAAs heterojunction bipolar transistors (HBT's)G have received considerable interest in microwave power applications. Large-signal CW powers of 0.6 and 1.0 W have been demonstrated at 3 and 10 GHz [l], [2], respectively, both with a power density of 3.33 W/mm. While the results are impressive, the collector-emitter breakdown voltages (l?Vceo) of these HBT's utilizing GaAs collector are limited to 12-20 V. For system applications which require high dc bias voltage operation, increasing the breakdown voltage past those achieved currently is necessary. An approach toward this goal is to replace the GaAs collector in the HBT with GaInP (bandgap = 1.89 eV), forming a GaInP/GaAs/GaInP double heterojunction bipolar transistor (DHBT). To date, I-V characteristics having a knee voltage less than 2 V [3] and small-signal performance with a maximum oscillation frequency of 35 GHz have been shown [4]. These dc and small-signal results, though encouraging, are far from being a relevant indication to what the large-signal performance would be. For example, the dc device characteristics of [ 3 ] are obtained from a DHBT with relaxed geometry and oversized emitter which is impractical for microwave applications. Similarly, the small-signal results of [4] are obtained from single or at most two-finger structures with greatly simplified device layout and processing which differ from those used for largesignal applications. Furthermore, the small-signal performance mentioned above were obtained at a low bias voltage of 4 V, whereas the desired bias voltage in a large-signal operation is significantly higher (approaching 20 V if possible). Most importantly, due to the extremely nonlinear characteristics of the base-emitter and base-collector junction capacitances, the large-signal performance can hardly be extrapolated from the small-signal performance.In this work, we present the first large-signal power performance of a GaInP DHBT, providing an indication to the . The authors are with Corporate R&D, Texas Instruments Inc., Dallas, TX IEEE Log Number 9401789. 15265. potential of high dc bias operation in GaInP DHBT for largesignal power applications. The DHBT demonstrates an S-band ( 3 GHz) CW output power of 1.51 W (3.77 W/mm) with a dc bias of 16 V and 1.19 W with a dc bias voltage of 20 V. Compared with AIGaAs/GaAs HBT large-signal results, which were obtained with a dc bias nominally 5 10 V [ 5 ] ,these results show the significant improvement in allowing the dc bias to increase by at le...

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