Self-timed circuits for energy harvesting AC power supplies

The recent explosion in capability of embedded and portable electronics has not been matched by battery technology. The slow growth of battery energy density has limited device lifetime and added weight and volume. Passive energy harvesting from vibration has potentially wide application in wearable and embedded sensors to complement or replace batteries. The authors proposed increasing energy harvesting efficiency by eliminating AC/DC conversion electronics. Self-timed circuits, power-on-reset circuitry and memory for energy harvesting AC power supplies has been investigated. The power-on-reset circuit achieves a substantial improvement over conventional approaches with 4.1 nW of simulated power dissipation and frequency-independent turn-on voltage. A chip is being fabricated to test the circuits presented here.