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Attofarad-Class Ultra-High-Capacitance Resolution Capacitive Readout Circuits
Guoteng Ren1,2, Saifei Yuan3, Jingjing Peng3
1College of Instrument Science and Opto-Electronics Engineering, Beijing Information Science and Technology University, Beijing 100192, China.
Abstract:
In order to meet the application requirements for high-precision and low-noise accelerometers in micro-vibration measurement and navigation fields, this paper presents the design and testing of an ultra-high-capacitance resolution capacitive readout circuit with attofarad-level precision. First, a differential charge amplifier circuit is employed for the first stage of capacitance detection. To suppress noise interference in the circuit, a frequency-domain modulation technique is utilized to mitigate low-frequency noise. Subsequently, a differential subtraction circuit is implemented to reduce common-mode noise. Additionally, an improved filtering circuit is designed to suppress noise interference in the final stage. The test results indicate that the designed circuit operates at a carrier frequency of 1 MHz, achieving a capacitance resolution of up to 0.103 aF/Hz1/2 and a noise floor of 25.6 μg/Hz1/2, thereby meeting the requirements for high-precision and low-noise capacitance detection in MEMS accelerometers.
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