Capacitance-to-voltage converter employing parallel-series passive charge integrator for low noise power efficient MEMS capacitive sensor

Zhong, Longjie; Shang, Pengpeng; Cao, Wenfei; Zhu, Zhangming; Liu, Shubin

doi:10.1016/j.mejo.2022.105369

Cited by 3 publications

(1 citation statement)

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“…Two main categories can be defined among capacitive sensor interfaces: the first one is represented by standard interfaces, without any compensation, which simply transduce the sensing parameter [19][20][21]25,26,28], while the second one collects interfaces that are able to compensate for parasitics by reducing the measurement error [22][23][24]27]. Moreover, an additional classification can be defined by considering the design approach, and, in particular, we can take into account both current-mode (CM) [23,25,27,28] and voltage-mode (VM) solutions [19][20][21][22]24,26,29].…”

Section: Introductionmentioning

confidence: 99%

A New Fully Closed-Loop, High-Precision, Class-AB CCII for Differential Capacitive Sensor Interfaces

et al. 2022

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The use of capacitive sensors has advantages in different industrial applications due to their low cost and low-temperature dependence. In this sense, the current-mode approach by means of second-generation current conveyors (CCIIs) allows for improvements in key features, such as sensitivity and resolution. In this paper, a novel architecture of CCII for differential capacitive sensor interfaces is presented. The proposed topology shows a closed-loop configuration for both the voltage and the current buffer, thus leading to better interface impedances at terminals X and Z. Moreover, a low power consumption of 600 µW was obtained due to class-AB biasing of both buffers, and the inherent drawbacks in terms of linearity under the mismatch of class-AB buffering are overcome by its closed-loop configuration. The advantages of the novel architecture are demonstrated by circuit analysis and simulations; in particular, very good robustness under process, supply voltage and temperature variations and mismatches were obtained due to the closed-loop approach. The CCII was also used to design a capacitive sensor interface in integrated CMOS technology, where it was possible to achieve a sensitivity of 2.34 nA/fF, with a full-scale sensor variation of 8 pF and a minimum detectable capacitance difference of 40 fF.

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