When heading into the millimeter wave frequency band, even wires on CMOS exhibit transmission line effects, this thesis therefore presents models, simulation and measurements for transmission lines on CMOS. The main goal is slow wave miniaturization, and models are explored for both a traditional CPW line above a silicon substrate and slow wave lines, emphasis is given on analytical over empirical formulations where loss is modeled by conductor skin effect, and conductive and dielectric polarization caused by the silicon substrate. Full 3D Electromagnetic simulation is used as a comparison, and to model more complex structures like a digitally tuned slow wave line. Models and simulations are compared to fabricated lines on a commercial CMOS process, where deembedding using the LL method is described in short. A new comb slow wave grounded coplanar waveguide (comb-S-GCPW) is presented, with an effective dielectric constant of 140 leading to a size reduction of 83 % compared to a traditional CPW. Applications of the published line is explored, with emphasis on filters.