Ku-band MMIC phase shifter using a parallel resonator with 0.18-/spl mu/m CMOS technology

A digital 5-bit phase shifter at Ku-band is presented, which is implemented with 0.18-mum RFCMOS technology. n-MOSFET switches and top metal microstrip lines with a first-metal ground allow the phase shifter to have small insertion losses. The proposed 90deg phase shifter utilizing a parallel resonator exhibits broad-band characteristics. All of the circuit components are derived to obtain a minimum phase variation at the operation frequency band. A bridged-T type phase shifter is also analyzed in view of parallel resonance using an ideal equivalent-circuit model. The conditions of the circuit elements are derived in an analytic form, which are used to obtain the broad-band phase characteristics. The fabricated 5-bit phase shifter demonstrates an overall rms phase error less than 12deg from 9 to 15 GHz. Insertion losses of 14.5 dB plusmn 0.5 dB and return losses less than 14 dB are obtained for 32 states at 12 GHz. The proposed 90deg phase shifter has performed a phase shift of 92.3degplusmn3.2deg over 9-15 GHz