An energy efficient inverter based readout circuit for capacitive sensor

Nguyễn, Thành Trung; Häfliger, Philipp

doi:10.1109/biocas.2013.6679705

Cited by 8 publications

(9 citation statements)

References 7 publications

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“…Owing to simple architecture, the proposed sensor interface covers reduced chip area and can operate on 0.8 V supply voltage. Although achieving a moderate Effective Number Of Bits (ENOB) and a similar FOM to the reported interfaces in [ 29 , 32 ], the proposed interface reduces power consumption significantly in contrast with the state of the art designs, which is especially suitable for low power application.…”

Section: Measurement Results and Discussionmentioning

confidence: 88%

“…However, due to the use of operational amplifier in Switched-Capacitor Amplifiers (SCA), this technique produces too much power dissipation which is unsuitable for passive designs. Accordingly, the inverter is proposed to replace the operational amplifier in SCA [ 28 , 29 ], which reduces the entire power dissipation significantly. However, they still employ relatively high supply voltage for ultra-low power design.…”

Section: Sensor Interfacementioning

confidence: 99%

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A CMOS Pressure Sensor Tag Chip for Passive Wireless Applications

Deng

et al. 2015

Sensors

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This paper presents a novel monolithic pressure sensor tag for passive wireless applications. The proposed pressure sensor tag is based on an ultra-high frequency RFID system. The pressure sensor element is implemented in the 0.18 µm CMOS process and the membrane gap is formed by sacrificial layer release, resulting in a sensitivity of 1.2 fF/kPa within the range from 0 to 600 kPa. A three-stage rectifier adopts a chain of auxiliary floating rectifier cells to boost the gate voltage of the switching transistors, resulting in a power conversion efficiency of 53% at the low input power of −20 dBm. The capacitive sensor interface, using phase-locked loop archietcture, employs fully-digital blocks, which results in a 7.4 bits resolution and 0.8 µW power dissipation at 0.8 V supply voltage. The proposed passive wireless pressure sensor tag costs a total 3.2 µW power dissipation.

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Section: Measurement Results and Discussionmentioning

confidence: 88%

Section: Sensor Interfacementioning

confidence: 99%

A CMOS Pressure Sensor Tag Chip for Passive Wireless Applications

Deng

et al. 2015

Sensors

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“…A two-step autocalibration method, shown in Fig. 5, is proposed to eliminate the offset value from the digital output code [8], [9]. An UP/DOWN counter is implemented to calibrate the digital output code.…”

Section: Two-step Autocalibrationmentioning

confidence: 99%

“…Consequently, this design increases the complexity and power consumption of the system. We have presented an approach to achieve an ultralow-power offset-free inverter-based CDC in [8] and [9] for both capacitive and resistive sensors with a lack of silicon implementation. This brief presents the fully measured characteristics of a complete physical system for biomedical capacitive sensors that is ready to be deployed in an implant, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

A Submicrowatt Implantable Capacitive Sensor System for Biomedical Applications

Trung

Häfliger

2015

IEEE Trans. Circuits Syst. II

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This brief presents a submicrowatt, offset-free, and implantable system for a biomedical capacitive sensor. The system is powered by a 13.56-MHz radio frequency signal and performs sensor signal amplification, analog-to-digital conversion, and load-shift keying uplink data transmission within 640 μs. An ultralow-power capacitance-to-digital converter (CDC) is designed by replacing a power-hungry operational amplifier with a subthreshold inverter in a switched-capacitor amplifier (SC-amp). A fast-response-gain compensation method is employed to reduce the gain error of the SC-amp while achieving high energy efficiency for the CDC. To eliminate the offset, a two-step autocalibration is applied. The application-specific integrated circuit is implemented in the Taiwan Semiconductor Manufacturing Company 90-nm complementary metal-oxide-semiconductor technology, and the whole system achieves an 8.02 effective number of bits with 9-bit linearity while consuming only 5.5 μW.Index Terms-Biomedical application, capacitive sensor, capacitive-to-digital circuit, implantable chip, load-shift keying (LSK), telemetry, wireless.

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“…The switched-capacitor (SC) amplifier is widely used in various low-power, high-precision analog circuits, such as sample-and-hold circuits [1,2], instrumentation amplifiers for intelligent sensors in strain, pressure and temperature measurement [3], micro-electromechanical systems (MEMS) capacitive accelerometers [4], multi-parameter sensing micro-systems [5], and readout amplifiers for biomedical signal acquisition systems [6][7][8]. Those amplifiers should have a very low DC offset and DC gain error as the output signals detected by the sensors are low-frequency and low-level.…”

Section: Introductionmentioning

confidence: 99%

A Novel Offset and Finite-Gain Compensated Switched-Capacitor Amplifier with Input Correlated Level Shifting

Chen

Guo³

et al. 2019

Electronics

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A novel offset and finite-gain compensated differential switched-capacitor(SC) amplifier is presented. Incorporating the correlated double sampling (CDS) technique and input correlated level shifting (CLS) technique together, the DC offset and DC gain error of SC amplifier are further reduced by a factor of op-amp DC gain compared with the conventional offset and finite-gain compensated SC amplifier. The effectiveness of the new scheme has been analyzed and verified by extensive simulations. An SC amplifier with the proposed scheme is designed in 130 nm CMOS technology. Simulated results show that with an op-amp having a low DC gain of 30 dB and an input offset of 10 mV, the proposed SC amplifier achieves an output offset and DC-gain error of 154 µV and 0.05%, respectively, which are significantly improved compared with 1.155 mV and 0.42% achieved in the conventional SC amplifier.

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An energy efficient inverter based readout circuit for capacitive sensor

Cited by 8 publications

References 7 publications

A CMOS Pressure Sensor Tag Chip for Passive Wireless Applications

A CMOS Pressure Sensor Tag Chip for Passive Wireless Applications

A Submicrowatt Implantable Capacitive Sensor System for Biomedical Applications

A Novel Offset and Finite-Gain Compensated Switched-Capacitor Amplifier with Input Correlated Level Shifting

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