Capacitive sensors are popular, especially due to the possibility to be integrated together with the readout circuit. In particular, differential implementations are intrinsically insensitive to common-mode noise. Unfortunately, stray capacitances can significantly alter the sensor output value, worsening the performance. This article proposes a novel solution based on an autotuning feedback loop to compensate for parasitic effects, thus preserving measurement performance. In particular, a voltage-controlled negative impedance converter is driven by a feedback loop, in order to control the current flowing in the sensor. The proposed solution can work with the both linear and hyperbolic type of sensors and with any voltage-mode sensor interfaces. An experimental setup, comprising the proposed compensating circuit, a De-Sauty bridge-based sensor front end and an emulated sensor, has been arranged to evaluate obtainable performance. Results show that the linearity error is decreased from more than 10%, without compensation, to less than 1%, when the proposed system is applied.
Titolo: | Full-Analog Parasitic Capacitance Compensation for AC-Excited Differential Sensors |
Autori: | |
Data di pubblicazione: | 2020 |
Rivista: | |
Handle: | http://hdl.handle.net/11697/153057 |
Appare nelle tipologie: | 1.1 Articolo in rivista |