Fully integrated inductive ring oscillators operating at V-DD below 2kT/q

摘要

This paper presents two fully integrated inductive ring oscillators that operate with supply voltages below 2kT/q for energy harvesting applications. Expressions for the oscillation frequency as well as the minimum transistor gain and supply voltage required for the starting up of oscillations are derived for each topology. The experimental results for two cross-coupled oscillators, with topologies comprised of a single-inductor and two-inductors per stage, are presented. The two oscillators operate with supply voltages as low as V (DD) = 46 mV at 11.5 A mu W DC power and V (DD) = 31 mV at 15 A mu W DC power, respectively, thus confirming the extremely low voltage operation of the prototypes integrated in a 130 nm technology.