High-resolution mm-wave array beamformers have applications in medical imaging, gesture recognition, and navigation. A scalable array architecture for 3D imaging is proposed in which single-element phase coherent transceiver (TRX) chips, with programmable TX pulse delay capability, are mounted on a common board to realize the array. This paper presents the design of the enabling TRX chip: a highly integrated 94 GHz phase-coherent pulsed-radar with on-chip antennas. The TRX achieves 10 GHz of frequency tuning range and 300 ps of contiguous pulse position control, enabling its usage in the large-array imager with time-domain TX beamforming. The TRX is capable of transmitting and receiving pulses down to 36 ps, translating to 30 GHz of bandwidth. Interferometric measurements show the TRX can obtain single-target range resolution better than 375 $mu$m (limited by equipment). Based on delay measurements, the time of arrival rms error would be less than 1.3 ps which, if used in a 3D imaging array, leads to less than 0.36 mm of RMS error in voxel size and position.