X-band microwave phase detector manufactured using GaAs micromachining technologies

A novel integrated X-band microwave phase detector fabricated using GaAs micromachining technologies is presented in this paper. The proposed phase detector is composed of a power combiner and a thermoelectric microwave power sensor based on the Seebeck effect. The power sensor is used to sense the power of the combined signal, which is proportional to the phase difference. This detector is compatible with GaAs MMIC technology. Since it is entirely composed of passive devices, zero dc power consumption is realized with a simple structure. Different power levels from 2 to 23 dBm at 10 GHz are applied to the detector, and the measured result shows a function of 1 + cos ψ (ψ is the phase difference). Good linearity appears from about 45° to 135°, and sensitivities are 58.57, 27.86, 14.52 and 7.22 µV deg−1 with 23, 20, 17 and 14 dBm signal applied, respectively. Frequency characteristics are measured at three different phase shifts, 0°, 90° and 180°, and the phase detector shows the frequency detection capability in principle, if a proper phase shifter is adopted.