A Ku-band 6-bit digital phase shifter MMIC for phased array antenna systems

This paper presents a 6-bit digital phase shifter designed at Ku-band for electronic beam steering of satellite based phased array antenna systems. The phase shifter is implemented using space qualified 0.25-μm pHEMT GaAs MMIC process. Each individual bit of the phase shifter is designed using optimum topology to achieve minimal insertion loss, accurate phase shifting and low amplitude variations. The measured performance of all 64 states of the phase shifter demonstrates an insertion loss of 6.1±0.6 dB with RMS phase error <; 1.3°, RMS amplitude error <; 0.35 dB and return losses better than 15 dB over 12-13 GHz frequency range. The circuit consumes negligible power (<;0.5mW) and has dimensions of 6.1×1.5 mm2 to fit in a multi-function single chip beam forming MMIC. The low insertion loss and high accuracy of the phase shifter are key features of the MMIC, making it suitable for high precision beam forming applications.