Embedded high-precision frequency-based capacitor measurement system

Abstract

This paper presents a direct way to measure the electrical value of capacitors embedded in a circuit using a ring-oscillator. A calibration system ensures robustness towards temperature, power supply and process variations. The measurement is largely automated to minimize the use of external instrumentation and to speed-up the measurement process while giving a digital signature of the capacitor value. Design-Of-Experiment (DOE) methodology has been conducted in order to validate the ability of the system to measure robustly a large range of small capacitors.