This article reports a test chip design in commercial 40-nm process technology to characterize the level of time-based degradation in metal-oxide-semiconductor field-effect transistors (MOSFETs). The two phenomena that have been concentrated on are the bias temperature instability (BTI) and the hot carrier injection (HCI). Stress tests have been carried out on both n- and p-MOSFETs with large channel widths and shorter channel lengths, as practically observed in analog and radio frequency circuits. Reliability characterization has been extended to cover the body effect and the impact of process variations both at prestress and poststress stages. The results demonstrate that the designed test chip has been instrumental in observing the extent of degradation due to BTI and HCI. Furthermore, both the body effect and the poststress variability have been found to affect the transistor and circuit performance significantly.