A VCF Loss-Control Tuning Loop for$Q$-Enhanced LC Filters

A loss-control tuning loop for
$Q$
-enhanced LC filters based on a voltage-controlled filter (VCF) is presented. The main factors affecting the tuning accuracy in this tuning scheme, including mismatches and frequency tuning errors, are discussed. The tuning scheme was implemented for a 1.5-V, 6-GHz
$Q$
-enhanced LC filter on a UMC 0.18-
$mu hboxm$
standard CMOS process. The design and measurement results are given. Effective loss control of the filter over process tolerances is demonstrated.