A Ka-Band Variable-Gain Phase Shifter With Multiple Vector Generators

A Ka-band variable-gain phase shifter (VGPS) using a multi-vector summation method is proposed, which represents both phase and amplitude by summing the I and Q signals of multiple vectors. The VGPS has an orthogonal phase and gain control function with a wide gain-control dynamic range because it is designed to keep the input and output impedances almost constant regardless of the control states. It shows a measured RMS phase error of 2.9 degrees during 17.3 dB gain control and that of 3.5 degrees during simultaneous 17.3 dB gain and 360 degrees phase control without any calibration from 30 to 32.5 GHz. The measured average insertion loss ranges from -4 to -2.8 dB from 28 to 33 GHz. It is implemented in a 65-nm RF CMOS process with the size of 0.21 mm(2) excluding pads.