On-chip artificial transmission lines, enabling compact Si-based mmWave ICs

On-chip integration of artificial (slow-wave) transmission lines (ATL) formed by periodic loading of microstrip lines with MIM capacitors is demonstrated, for the first time, using 0.18μm SiGe:C BiCMOS. We demonstrate 2× length-reduction of λ/4-stub RF choke and filters at 38GHz and at 77GHz. Due to the extensive use of TLs in mmWave design, ATL has more potential for enabling compact mmWave design than technology scaling. A simplified theory is also presented to design mmWave ATLs. Finally, BEOL-based metal-on-metal (MOM) capacitor instead of MIM capacitor is proposed for ATL improvement based on RF characterization of 65nm CMOS.