Characterization of Integrated Transmission Lines for RF Bandpass ΣΔ Modulators

The specifications of microstrip (MS), coplanar waveguide (CPW) and various tapered transmission lines (TLs) intended for an integrated RF TL based sigma delta modulator (ITLSDM) are discussed. The EM simulator Sonnet is used to achieve accurate models for TLs in a 0.25um BiCMOS technology. The physical parameters of different TLs are compared in order to achieve the guidelines, which ends up to a saved area and power consumption in the modulator. The equations for an area efficient meandering is given, which shows the area-quality factor trade-off. The results are supported with theoretical facts and verified with a resonator employed in a 4
^th
order f
_s
/4 bandpass SDM tuned at a center frequency of 2.5 GHz.