Future high-speed analog and digital systems that will benefit significantly from reduced power consumption while maintaining high data transmission rates include wireless applications, space-based, micro-air-vehicles and other portable systems used for communications, imaging, data processing, and sensing. The development of Sb-based transistors for use in low-noise high-frequency amplifiers, digital circuits, and mixed-signal circuits will provide the enabling technology needed to address these rapidly expanding needs. We report on the development of an npn double heterojunction bipolar transistor (DHBT) with an InGaSb base and InAlAsSb alloys for the emitter and collector. The combination of alloys with a lattice constant of 6.2Å is illustrated in Fig. 1. Silvaco simulations indicate that large collector currents, Ic, are possible with this system at smaller base-emitter voltages, VBE, than are measured in the InP based HBTs. An important advantage of this system is that the conduction band offset between the InGaSb base and the InAlAsSb may be tuned over a large range while maintaining large valence band offsets that are useful for minimizing parasitic base currents. A problem with the InAlAsSb alloys is the difficulty of growing mixed group V alloys.