A 12-dB Gain Q-Band Vector-Modulator Phase Shifter in 130 nm SiGe HBT BiCMOS Technology

This paper presents the design and measured results of a vector modulator phase shifter for the Q-band, implemented in 130 nm SiGe HBT BiCMOS technology. A Lange coupler and transformer-type baluns generate differential in-phase (I) and quadrature (Q) signals at the input. Capacitive termination of the balun primary coil reduces simulated amplitude imbalance by 0.5 dB across the target bandwidth. Phase and gain control are achieved through four analog control voltages modulating the I/Q collector currents. On-wafer measurements up to 43.5 GHz validate the design, demonstrating 5.625° phase resolution and a high peak gain of 12 dB with a 3 dB bandwidth of 33–42 GHz. Within this range, measured RMS phase and gain errors are below 5.2° and 0.8 dB, respectively. The linearity of the phase shifter was characterized through two-tone intermodulation tests at 37.5 GHz, and the average output referred third-order-intercept point (OIP3) was measured as 10.5 dBm. The total chip area is 0.62 mm2, while the core circuit occupies 0.372 mm2.