Design of a Compact Wideband SPDT Switch With High Isolation for Sub-6 GHz Applications
Nengxu Zhu, Yiting Zhang, Zenglong Zhao, Fanyi Meng
Abstract
This paper presents a compact DC-to-6 GHz single-pole double-throw (SPDT) switch utilizing embedded <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RLC</i> resonator technology. Building upon the traditional series-shunt RC structure, an inductor is incorporated between the series and shunt transistors, working in conjunction with the port-matching inductors to achieve broadband low-loss characteristics in the through mode. In the isolation mode, the structure forms an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RLC</i> resonator to enhance isolation. To improve linearity, quadruple-stacked transistors are employed for both the series and shunt-switching transistors. Fabricated using the SMIC 0.13 μm CMOS SOI process, the measurement results demonstrate that the chip achieves an isolation of >50 dB across the DC-to-6 GHz range, with an insertion loss of only 0.4–1.2 dB and an input power at 1 dB compression point (IP<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub>) of 20 dBm at 5 GHz. The core area of the chip is only 0.06 mm².