Amplitude-enhanced ring oscillator using a new bootstrapped technique suitable for energy harvesters

摘要

In this paper, a new local supply boosting technique (LSBT) is proposed which significantly enhances oscillation amplitude of ring oscillators (RO). By modifying the booster part of the unit delay elements, the boosting capacitors are charged to higher voltages compared with the conventional counterparts, resulting in higher boosting efficiency. Dynamic body biasing (DBB) are also employed to further improve the oscillation frequency by increasing the current driving capability of the transistors. The proposed architecture is mostly suitable for DC-to-AC conversion in energy harvesters where under stringent supply and power conditions a high oscillation amplitude and frequency is desired. As a proof of concept, the proposed ultra-low voltage amplitude-enhanced RO is implemented in a 0.18 mu m CMOS process. Under a 250 mV supply voltage, the oscillation amplitude is 558 mV corresponding to about 220% amplitude enhancement, consumes 27.3 nW of power and oscillates at 147 kHz. (C) 2019 Elsevier GmbH. All rights reserved.