A Fully-Analogue Light-to-Frequency Converter Circuit for Optical Sensing Applications

Stanchieri, Guido Di Patrizio; Marcellis, Andrea De; Faccio, Marco; Palange, E.; Güler, Ülkühan

doi:10.1109/jsen.2022.3187943

Cited by 4 publications

(2 citation statements)

References 56 publications

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“…On the other hand, when the specific application requests the output of the CV-AFE be a DC or AC voltage signals, the design architecture mainly employs a fully-analog approach; for example, this is the case for driving high-refresh-rate AMOLED displays [ 28 ], to control accelerometer, gyroscopes and positioning sensors [ 35 , 36 , 38 ]. The proposed CV-AFE circuit belongs to the latter class of converters since its DC output voltage can be employed to control the variations of the pneumatic muscle elongation or contraction with respect to a C-MKM initial value or rest condition by using suitable analog actuators [ 40 , 41 , 42 , 43 , 44 ]. The CV-AFE circuit has been implemented on a laboratory breadboard by using Commercial Off-The-Shelf (COTS) discrete components whose values have been chosen by considering variations of the C-MKM length up to 50 mm corresponding to a change of the C-MKM capacitance up to 25 pF.…”

Section: Introductionmentioning

confidence: 99%

A Current-Mode Analog Front-End for Capacitive Length Transducers in Pneumatic Muscle Actuators

Di Patrizio Stanchieri,

De Marcellis,

Faccio

et al. 2024

Micromachines

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This paper reports on the design, implementation, and characterization of a current-mode analog-front-end circuit for capacitance-to-voltage conversion that can be used in connection with a large variety of sensors and actuators in industrial and rehabilitation medicine applications. The circuit is composed by: (i) an oscillator generating a square wave signal whose frequency and pulse width is a function of the value of input capacitance; (ii) a passive low-pass filter that extracts the DC average component of the square wave signal; (iii) a DC-DC amplifier with variable gain ranging from 1 to 1000. The circuit has been designed in the current-mode approach by employing the second-generation current conveyor circuit, and has been implemented by using commercial discrete components as the basic blocks. The circuit allows for gain and sensitivity tunability, offset compensation and regulation, and the capability to manage various ranges of variations of the input capacitance. For a circuit gain of 1000, the measured circuit sensitivity is equal to 167.34 mV/pF with a resolution in terms of capacitance of 5 fF. The implemented circuit has been employed to measure the variations of the capacitance of a McKibben pneumatic muscle associated with the variations of its length that linearly depend on the circuit output voltage. Under step-to-step conditions of movement of the pneumatic muscle, the overall system sensitivity is equal to 70 mV/mm with a standard deviation error of the muscle length variation of 0.008 mm.

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Section: Introductionmentioning

confidence: 99%

A Current-Mode Analog Front-End for Capacitive Length Transducers in Pneumatic Muscle Actuators

Di Patrizio Stanchieri,

De Marcellis,

Faccio

et al. 2024

Micromachines

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“…In general, for biomedical applications, the development of optical sensing devices requires low-cost and portable technology operating in low-voltage, low-power conditions. These requirements can be fulfilled by employing integrated optoelectronics sensors in standard CMOS technology combined with digital-based pulse-wave analysis techniques [9,10]. Optical sensor systems are also widely used in other fields of safety-healthcare applications, such as in wearable prosthetic systems [11][12][13][14], where a single or array of sensors are designed to increase the day-to-day patient life quality.…”

Section: Introductionmentioning

confidence: 99%

A 180 nm CMOS Integrated Optoelectronic Sensing System for Biomedical Applications

et al. 2022

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This paper reports on a CMOS fully integrated optoelectronic sensing system composed of a Si photodiode and a transimpedance amplifier acting as the electronic analog front-end for the conditioning of the photocurrent generated by the photodiode. The proposed device has been specifically designed and fabricated for wearable/portable/implantable biomedical applications. The massive employment of sensor systems in different industrial and medical fields requires the development of small sensing devices that, together with suitable electronic analog front ends, must be designed to be integrated into proper standard CMOS technologies. Concerning biomedical applications, these devices must be as small as possible, making them non-invasive, comfortable tools for patients and operating with a reduced supply voltage and power consumption. In this sense, optoelectronic solutions composed of a semiconductor light source and a photodiode fulfill these requirements while also ensuring high compatibility with biological tissues. The reported optoelectronic sensing system is implemented and fabricated in TSMC 180 nm integrated CMOS technology and combines a Si photodiode based on a PNP junction with a Si area of 0.01 mm2 and a transimpedance amplifier designed at a transistor level requiring a Si area of 0.002 mm2 capable to manage up to nanoampere input currents generated by the photodiode. The transimpedance amplifier is powered at a 1.8 V single supply showing a maximum power consumption of about 54 μW, providing a high transimpedance gain that is tunable up to 123 dBΩ with an associated bandwidth of about 500 kHz. The paper reports on both the working principle of the developed ASIC and the experimental measurements for its full electrical and optoelectronic characterizations. Moreover, as case-examples of biomedical applications, the proposed integrated sensing system has also been validated through the optical detection of emulated standard electrocardiography and photoplethysmography signal patterns.

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A Current-Mode Analog-Front-End for Capacitance-to-Voltage Conversion of Length Transducers in Pneumatic Artificial Muscles

Stanchieri,

De Marcellis,

Faccio

et al. 2024

2024 IEEE 15th Latin America Symposium on Circuits and Systems (LASCAS)

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A Fully-Analogue Light-to-Frequency Converter Circuit for Optical Sensing Applications

Cited by 4 publications

References 56 publications

A Current-Mode Analog Front-End for Capacitive Length Transducers in Pneumatic Muscle Actuators

A Current-Mode Analog Front-End for Capacitive Length Transducers in Pneumatic Muscle Actuators

A 180 nm CMOS Integrated Optoelectronic Sensing System for Biomedical Applications

A Current-Mode Analog-Front-End for Capacitance-to-Voltage Conversion of Length Transducers in Pneumatic Artificial Muscles

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