Embedded high-precision capacitor measurement system based on ring-oscillator

A direct way to measure the electrical value of capacitors embedded in a circuit using a ring-oscillator is presented. A calibration system ensures the robustness of the measurement process against temperature, power supply and process variations. Silicon results show the ability of the system to measure robustly a large range of small capacitors. The system also provides a noise immunity as the system provides a digital signature of the capacitor value.