A compact CMOS Marchand balun incorporating meandered multilayer edge-coupled transmission lines

Abstract

This work presents a compact CMOS Marchand balun design, which consists of the meandered two-conductor edge-coupled complementary-conducting-strip coupled-line (CCS CL). The CCS CL, which is fully compatible with the standard CMOS process, provides various structural parameters to synthesize the desired coupling coefficient for Marchand balun realization. The prototype, which is fabricated by the standard 0.18-mum 1P6M CMOS technology, reveals circuit size of 240.0 mum times 240.0 mum (without contact pads). The measured results, which are collected based on 50-Omega system, demonstrate excellent agreements with those of the simulations. The input return loss is less than -15.0 dB from 21.6 GHz to 33.1 GHz. The measured insertion losses between input and two output ports (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> and S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sub> ) are 5.90 dB and 4.38 dB at 23.6 GHz, respectively. The phase difference between two output ports is 180deg plusmn 10deg from 15.5 GHz to 40.0 GHz.