High Self-Resonant and Area Efficient Monolithic Transformer Using Novel Intercoil-Crossing Structure for Silicon RFIC

Abstract

Novel on-chip multiport symmetrical transformer that has high self-resonant frequency and good area efficiency is presented. This technique involves the unique way of intercrossing the transformer's primary and secondary coil using multiple metallization layers. A stacked transformer, with the same area utilization as the proposed device, is selected for performance comparison. The proposed design has demonstrated a higher self-resonant frequency in differential transmission line transformer configuration, i.e., <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SRF(Stacked)</sub> = 8 GHz and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SRF(Sym)</sub> = 10.35 GHz. The structure presented is fully compatible with standard CMOS foundry processes. The silicon data reported in this letter are based on Chartered Semiconductor Manufacturing's 0.13- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mu</i> m RFCMOS technology node.