38 GHz All-pass Phase Shifter with Attenuator Using 0.15 µm GaAs Technology for Wireless Sensors

A 38 GHz all-pass phase shifter designed using the pHEMT 0.15 m GaAs process is presented. The phase shifter consists of two groups of a low-pass filter (LPF) with a 90 phase shift and attenuators. By tuning the bias voltage, the magnitude and phase of the signal are changed. At the end of the circuit, a power combiner is used to obtain a 360 all-pass output signal. The measurement results show that the phase shifter can achieve phase variation with an insertion loss of about 10 dB and an all-pass work function around a center frequency of 38 GHz. The chip area is about 1.12 mm 2 . The phase shifter is suitable for sensing circuitry.