A Four-Port Microwave Phase Detector at $X$ -Band Based on MEMS Power Sensors

A four-port microwave phase detector based on MEMS power sensors at X-band (8-12 GHz) is proposed in this paper. It consists of two power dividers, two power combiners, two phase shifters, and two MEMS power sensors. Four power dividers/combiners and two phase shifters compose a four-port junction to expand the phase detection range. A thermoelectric power sensor and a capacitive power sensor compose the MEMS power sensor for low and high power measurement. Two types of power sensors can improve the measurement range and enhance the overload capacity. This microwave phase detector is fabricated by GaAs monolithic microwave integrated circuit technology. Experiments show that its return loss is better than -10 dB, and the isolation is better than -13.2 dB over X-band. Measured results of the phase shift fit well with the calculated results in an entire cycle of -180°~+180°. The phase detection sensitivities are 16.62 μV/° and 23.94 aF/°, and the response times are 0.408 ms and less than 20 ms for the two types of sensors, respectively. The dynamic range of phase detector can be expanded up to 4 W, which is almost quintuple our previous works.