A Variable Gain Phase Shifter Based on Hybrid Control Scheme

In this paper, a Q-band variable gain phase shifter (VGPS) based on hybrid control scheme is presented, which is fabricated in a 65nm bulk CMOS process. The proposed hybrid control scheme for the VGPS includes overall passive gain control (insertion loss control of the passive baluns) and separate active gain control on the I/Q paths. Two Gilbert-cell-based variable gain amplifiers (VGAs) are used to provide variable-gain signals on the I/Q paths respectively. The proposed insertion-loss-tunable (ILT) balun containing a conventional octagonal balun and an additional thin-metal inductor is proposed, which is used to increase the gain control range and resolution. The VGPS synthesizes a vector by summing I/Q signals in the rectangular I/Q generator.In terms of 6-bit phase tuning within 360 ° and 5-bit gain tuning with a range of 15.5dB at 40GHz, the RMS gain and phase errors are 0.57dB and 0.89 ° respectively. The peak gain of the maximum gain states is -7dB. The VGPS consumes a DC power of 30mW and occupies a core chip size of 0.269.