This paper describes the modeling and the design of a ladder-structured multilayer-coplanar-waveguide-based tunable differential inductor with wide tuning range and high quality factor. The impacts of process variation on the performance of the inductor and active components are mitigated through postfabrication tuning. A configurable 77-GHz voltage-controlled oscillator (VCO) with a tunable inductor has been designed and implemented in a 65-nm single-poly six-metal bulk CMOS technology. Techniques for tuning the center frequency and increasing the tuning range are described. Under a 1.5-V supply, the measured VCO can be tuned from 67.3 to 77.9 GHz, i.e., 15.8%, while consuming 14.3 mW; the output power is -4.5 dBm, and the phase noise at a 10-MHz offset from the 77-GHz carrier is -108.4 dBc/Hz. This configurable VCO provides a wide tuning range and immunity to process variation.