In this paper, a fundamental W-band monolithic microwave integrated circuit (MMIC) voltage controlled oscillator (VCO) featuring high output power and wide tuning range is proposed. The VCO is fabricated utilizing 0.8μm InP DHBT technology with peak f_Tand f_max of 170 and 250 GHz, respectively. The VCO core implements a balanced Colpitts-type topology. An additional buffer amplifier stage is connected with the VCO core to further boost output power as well as eliminate the load pulling effect. The DHBT base-collector P-N junction at reverse bias is chosen as varactor diode to realize a wide frequency tuning. The measured results demonstrate that the oscillation frequency of the proposed VCO can be tuned between 81- 97.3GHz, which is a relative tuning bandwidth of 18.3 %. Over this frequency range the maximum output power of 10.5 dBm is achieved, and the power variation is less than 3.5 dB. A phase noise of -88 dBc/Hz @1MHz is obtained at the highest oscillation frequency. To the authors’ best knowledge, this is the highest output power with such a wide tuning range reported for a W-band InP DHBT MMIC VCO.