Energy‐efficient leakage‐based oscillator with stacked structure for nW harvesters.

An ultra‐low‐power oscillator with 0.24 pJ/cycle energy efficiency is presented, suitable for nanowatt‐level energy harvesters. The sub‐pJ/cycle energy efficiency is comparable with the lowest energy per cycle costs of prior arts and is achieved by minimising short‐circuit current with a leakage‐based delay cell and minimising dynamic power consumption with a capacitively coupled stacked structure. The proposed oscillator is fabricated in 180 nm CMOS process. Under 2.2 V supply voltage, the energy per cycle is 0.24 pJ/cycle over a frequency range of 18.2–226 kHz. [ABSTRACT FROM AUTHOR]