We report, for the first time, the successful fabrication of aluminum-free metamorphic (MM) InP/In 0 53 Ga 0 47 As/InP double heterojunction bipolar transistors (DHBTs) on GaAs substrates with a linearly graded In Ga 1 P buffer grown by solid-source molecular beam epitaxy (SSMBE). Device with 5 5 m 2 emitter displays a peak current gain of 40 and a common-emitter breakdown voltage (BV CEO ) higher than 9 V, a current gain cut-off frequency ( ) of 48 GHz and a maximum oscillation frequency ( max ) of 42 GHz. A minimum noise figure of 2.9 dB and associated gain of 19.5 dB were measured at a collector current level of 2.6 mA at 2 GHz. Detailed analysis suggests that the degradation of the base-emitter heterojunction interface and the increase of bulk recombination are the most probable causes for the poorer device performance of the current metamorphic HBTs compared to the lattice-matched HBTs.