CMOS phase shifter with low phase-variation VGA for V-band application and Ku-band scaled design

A 90° fine tuning phase shifter design with low insertion phase-variation a VGA for V-band phased array systems is presented. The vector-sum phase shifters require low phase-variation VGAs with a gain control range of about 10 dB for good digital control performance. The measured data for discrete devices have found that a cascode has 20° better phase variation performance than a common source in the required gain control range at 50 GHz. To demonstrate the design, the Ku-band scaled phase shifter has been fabricated in 0.13 μm standard CMOS process. It consists of 90°/0° hybrids with lumped elements and two cascode VGAs. The 91° continuous phases with the gain of 2.7 ± 0.9 dB are obtained at 13 GHz.