A 0.1nW −1µW All-Dynamic Capacitance-to-Digital Converter with Power/Speed/Capacitance Scalability

Abstract

A versatile, low power and energy efficient Capacitance-to-Digital Converter (CDC) for Internet-of-Things (IoT) is presented, based on an all-dynamic architecture with adaptable speed, resolution and range. Sampling rates from 1S/s up to 100kS/s are supported and capacitances from 1.23 to 24.59pF can be digitized while the power scales inherently from 0.1nW to 1µW. This makes the design versatile to efficiently deal with a variety of sensors with different speed requirements and different capacitance values. The 0.1nW lowest absolute power is >20x smaller than prior-art, and the Figure-of-Merit (FoM) from 18 to 59fJ/conv-step is also the lowest among prior designs. As example, by connecting a MEMS pressure sensor, this chip can measure environmental pressure with only 0.8nW at a speed of 100S/s.