Design a V-band 4×4 Butler matrix for switched beam-forming operation

A compact V-band 4×4 Butler matrix, using 0.35 μm SiGe bipolar process, is proposed in this work. This design exhibits an average insertion loss of 3 dB with amplitude variation less than 1.5 dB and an average phase imbalance of less than 10 degrees from 55 GHz to 65 GHz. The chip area is only 0.5×0.9 mm
²
including all pads. The SiGe Butler matrix is an excellent candidate for MIMO systems and applied in high data-rate communications.