A <i>K-/Ka</i>-Band Active Double-Pole-Double-Throw Switch Using a Bidirectional Amplifier and Switchable Inductance Technique

Abstract

This article proposes and implements a bidirectional active double-pole-double-throw (DPDT) switch that applies a switchable inductance technique using the 40-nm general purpose (GP) 1P9M CMOS process for a dual-polarization system. To reduce the insertion loss and address the isolation issue of the passive DPDT structure, the active DPDT structure comprises four bidirectional amplifiers (BDAs) to provide the gain. By controlling whether the different BDAs turn on, the active DPDT switch implements straight and cross-transmission functions to control the left and right circular polarization. We use the multiple symmetrical layout method to integrate the four BDAs into a single circuit to conserve chip area and dc power. In addition, we use the switchable inductance technique to implement the matching network to switch to different operating frequencies and extend the equivalent 3-dB bandwidth (BW). At 28 and 34 GHz, the measured average gains are 6.78 and 5.65 dB, respectively. When the control voltages are 0 and 0.9 V, the measured 3-dB BW is approximately 11 and 11.5 GHz, respectively, and the equivalent 3-dB BW is approximately 17.25 GHz across all states. Under all states, the measured average IP1 dB values are -0.25 and -2.5 dBm at 28 and 34 GHz, respectively. The measured reverse isolation and isolation between the two paths are better than 25 dB across all states. Under different modes, the measured amplitude and phase imbalances are less than +/- 0.2 dB and +/- 2(degrees), respectively, in the range of 10-50 GHz. The measured average noise figures at 28 and 34 GHz are 6.62 and 7.84 dB across all states, respectively. At a supply voltage of 0.9 V, the dc power of the proposed DPDT system is only 16.56 mW, and each path consumes 8.28 mW. With respect to the active switch modules reported in other studies, the proposed active DPDT switch demonstrates the lowest dc power, compact area, improved linearity, high isolation, and better figure of merit (FoM).