We demonstrate the photonic generation of an ultra-wideband millimeter-wave (MMW) signal (white-light), which covers the full W-band (75-110 GHz). A W-band photonic emitter (PE) with a wide 3-dB optical-to-electrical bandwidth (30 GHz, 80-110 GHz), constructed by integrating a planar quasi-yagi radiator for feeding the WR-10 waveguide-based horn antenna and a high-power near-ballistic uni-traveling-carrier photodiode, serves as the key component in our system. Two different kinds of optical sources are adopted to excite our emitter, one is a broadband amplified-spontaneous-emission source and the other is a fast-sweeping wavelength laser for simultaneous and very-fast scanning (35 GHz/ms) MMW white-light generation, respectively. Compared with the traditional solid-state MMW white-light (noise) generator and reported photonic approach, our demonstrated solution has the advantages of simpler configuration, higher output MMW power density, and a much faster scanning rate, due to excellent high-power performance of our wideband PE.