Two High-Precision Proximity Capacitance CMOS Image Sensors with Large Format and High Resolution

This paper presents newly developed two high-precision CMOS proximity capacitance image sensors: Chip A with 12 µm pitch pixels with a large detection area of 1.68 cm²; Chip B with 2.8 µm pitch 1.8 M pixels for a higher resolution. Both fabricated chips achieved a capacitance detection precision of less than 100 zF (10⁻¹⁹ F) at an input voltage of 20 V and less than 10 zF (10⁻²⁰ F) at 300 V due to the noise cancelling technique. Furthermore, by using multiple input pulse amplitudes, a capacitance detection dynamic range of up to 123 dB was achieved. The spatial resolution improvement was confirmed by the experimentally obtained modulation transfer function for Chip B with various line and space pattens. The examples of capacitance imaging using the fabricated chips were also demonstrated.