A 200–250-GHz Phase Shifter Utilizing a Compact and Wideband Differential Quadrature Coupler

This letter presents the design of a 200–250-GHz compact vector modulator (VM) phase shifter in a 0.13- $\mu \text{m}$ SiGe bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. A compact, low-loss, and wideband differential quadrature coupler is used to generate differential I/Q signals. The design details of the millimeter-wave wideband differential coupler is presented and compared with other I/Q generators by the 3-D electromagnetic (EM)-simulated results. The VM core is realized by two variable gain amplifiers based on Gilbert cell architecture. The measured phase shifter shows a gain of −10.3 dB for the maximum gain setting at 230 GHz. The phase shifter shows a −17 dB of gain for full 360° phase tuning range and a 10 dB of gain control. The maximum rms gain error and the phase error are 1.25 dB and 10°, respectively, from 200 to 250 GHz. The chip consumes a dc power of 55 mW and occupies a core area of 0.09 mm ² .