A drift-diffusion-like formulation for including ballistic and quasi-ballistic transport in the simulation of double-gate MOSFETs has been implemented in a technology computer-aided design (TCAD) simulator. This model is based on a description of the quasi-ballistic mobility through a dynamical description of the mean free path. The model has been validated by comparison with experimental data and Monte Carlo simulation. In addition, several circuit elements (CMOS inverter, powerless XOR gate, and ring oscillator) have been simulated in the TCAD environment, illustrating the impact of ballistic and quasi-ballistic transport on static and transient performances at the circuit level.