Abstract: Based on the accurate modeling of equivalent circuit for the Schottky diode, the design and fabrication of a W-band broadband power detector with high sensitivity is presented in this paper. According to the physical structure of the GaAs low barrier Schottky diode (LBSD), an equivalent circuit model of the diode is developed. Parameters of the circuit model are accurately extracted, by using the measured results of an experimental detector module at W band. Based on the equivalent circuit model, matching networks are optimized to meet with the bandwidth requirements of 78～98 GHz. The measured results of the W-band broadband detector demonstrate that the highest voltage sensitivity is 7000 mV/ mW at 82GHz, and the sensitivity is higher than 1500 mV/ mW from 78 GHz to 98 GHz, when input power is -30 dBm. Measured tangential sensitivity (TSS) is better than -36 dBm. Consistency between the measurements and simulations validates the accuracy of the equivalent circuit model.