A 2amp;#x00B5;A temperature compensated mems-based real time clock with amp;#x00B1;4 ppm timekeeping accuracy

摘要

This paper presents a MEMS-based real time clock with a temperature compensation system. The implemented circuit achieves a timekeeping accuracy of ±4 ppm over −40 °C… 85 °C temperature range. It is built using a 27 kHz silicon resonator, differential PTAT temperature sensor with a 2nd order ΣΔADC, and a DSP block for temperature frequency compensation. The circuit is powered by a 1.8V supply and draws 2 µA current. The system has been implemented using a 0.18 µm CMOS process.