| Harvesting energy from parasitic vibrations in the environment of a wireless sensor node can extend operating lifetime beyond the limitations of battery and capacitor technology. An efficient rectifier is needed to convert most of the energy harvested by piezoelectric vibration-based energy harvesters into a usable DC supply voltage. A highly efficient full-wave rectifier has been fabricated previously in 0.35microm CMOS technology to produce the DC supply with minimal ripple [1]. In this thesis, the same rectifier is ported to 90nm CMOS technology and verified using extensive post-layout simulation. Furthermore, a CAD tool that automatically generates an n-input rectifier schematic and layout given transistor sizes has been developed. The rectifier, scaled for maximum power efficiency for input amplitudes of 0.2V, 0.4V, 0.6V, 0.8V, and 1V, produces simulated power efficiencies of 84.85%, 95.64%, 97.57%, 98.15%, and 98.33% respectively. At the same time, the power delivered to a 22 kO load assuming 1V amplitude is 22.11microW with the rectifier occupying an area of 330microm2. |
