Design of a Carrier Wave for Capacitive Transducer with Large Dynamic Range

Li, Zhu; Zhang, Xian; Zou, Shu; Huang, Xiaosong; Xue, Changxi; Liu, Jianping; Liu, Qi; Yang, Shan-Qing; Tu, Lai

doi:10.3390/s20040992

Cited by 3 publications

(1 citation statement)

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“…A terrific stable capacitive sensing circuit of the bandwidth down to 0.1 mHz has carefully been studied [7][8][9][10] for space gravitational wave detection mission LISA, and in-flight tests have achieved the anticipated goal at mHz bandwidth in LISA Pathfinder mission [11,12]. In our lab, a similar capacitive position transducer has also been developed, the effect of the excitation frequency in differential capacitive sensing, the prototype sensing circuit, and a pre-scanning and adjustment method are investigated, respectively [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Investigation on Stray-Capacitance Influences of Coaxial Cables in Capacitive Transducers for a Space Inertial Sensor

Wang

et al. 2020

Sensors

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Ultra-sensitive inertial sensors are one of the key components in satellite Earth’s gravity field recovery missions and space gravitational wave detection missions. Low-noise capacitive position transducers are crucial to these missions to achieve the scientific goal. However, in actual engineering applications, the sensor head and electronics unit usually place separately in the satellite platform where a connecting cable is needed. In this paper, we focus on the stray-capacitance influences of coaxial cables which are used to connect the mechanical core and the electronics. Specially, for the capacitive transducer with a differential transformer bridge structure usually used in high-precision space inertial sensors, a connecting method of a coaxial cable between the transformer’s secondary winding and front-end circuit’s preamplifier is proposed to transmit the AC modulated analog voltage signal. The measurement and noise models including the stray-capacitance of the coaxial cable under this configuration is analyzed. A prototype system is set up to investigate the influences of the cables experimentally. Three different types and lengths of coaxial cables are chosen in our experiments to compare their performances. The analysis shows that the stray-capacitance will alter the circuit’s resonant frequency which could be adjusted by additional tuning capacitance, then under the optimal resonant condition, the output voltage noises of the preamplifier are measured and the sensitivity coefficients are also calibrated. Meanwhile, the stray-capacitance of the cables is estimated. Finally, the experimental results show that the noise level of this circuit with the selected cables could all achieve 1–2 × 10−7 pF/Hz1/2 at 0.1 Hz.

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