A Sampling Based Clock Calibration Technique for Low Power Systems

This paper presents a novel approach for oscillator calibration suited mainly for IoT and other low power devices. As a matter of fact, oscillators in integrated circuits can see their resonance frequency altered due to process, voltage and temperature variations. Using an external reference, often available in IoT devices, the proposed solution uses the sampling theory to estimate the real oscillator frequency and to perform the correction. An electrical implementation of the approach in a 0.18 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathbf{m}$</tex> CMOS technology is presented for a leadless pacemaker scenario. The calibration of the 4 MHz oscillator has a precision of 0.5% and consumes only 0.69 nJ.