A new interface weak-capacitance detection ASIC of capacitive liquid level sensor in the rocket

摘要

A new capacitive liquid level sensing interface weak-capacitance detection ASIC has been designed. This ASIC realized the detection of the output capacitance of the capacitive liquid level sensor, which converts the output capacitance of the capacitive liquid level sensor to voltage. The chip is fabricated in a standard 0.5 mu m CMOS process. The test results show that the linearity of capacitance detection of the ASIC is 0.05%, output noise is 3.7 aF/root Hz (when the capacitance which will be detected is 40 pF), the stability of capacitance detection is 7.4 x 10(-5) pF (1 sigma, 1 h), the output zero position temperature coefficient is 4.5 uV/degrees C. The test results prove that this interface ASIC can meet the requirement of high accuracy capacitance detection. Therefore, this interface ASIC can be applied in capacitive liquid level sensing and capacitive humidity sensing field.