A 36 - 38 GHz 4-Bit Switch-Type Phase Shifter with Low Insertion Loss for Soil Moisture Radiometer Antenna

A Ka-band GaAs Monolithic Microwave Integrated Circuit (MMIC) 4-bit digital phase shifter for a soil moisture radiometer phased array antenna is presented. The phase shifter is comprised of GaAs pHEMT passive devices and high-pass/low-pass (HP/LP) and switched filter networks. The passive HEMT's gate is biased with 0 or -3 V to control the desired phase shifts. The simulation results demonstrate 11 ± 1 dB insertion loss (IL) and the input and output return loss (RL) is higher than 8.8 dB over the band of 36 - 38 GHz. The root mean square (RMS) phase error is smaller than 4° within the band. The phase shifter is designed using 0.15 μm GaAs pHEMT process. The phase shifter power consumption is almost zero. The chip size is about 2 mm × 1 mm, including the pads and scribe lines.