A Micro Capacitance Measurement System with Ultra-High Accuracy and Fast Speed

It remains a challenge to measure the capacitance of miniaturized capacitive sensors, usually on the order of pF, with a high accuracy and a fast speed. In this work, a novel differential capacitance measurement method is proposed, aiming for capacitance measurements for capacitive sensing devices. The design includes 7 modules: a sine wave generator, a low pass filter, amplification circuit, peak detection circuit, a differential amplification circuit, an A/D acquisition module circuit and a Bluetooth module. The system generates an AC signal with a frequency of 200 kHz and a variable peak-to-peak value up to 4 V. Our system has achieved a high measurement precision with the error below 0.1%, a high sensitivity of 1 V/pF, fast readout speed up to 10 kHz and excellent capacitance resolution of 3 fF.