AZKA cell, the current-mode alternative of Wheatstone bridge

Azhari, Seyed Javad; Kaabi, Hooman

doi:10.1109/81.883322

Cited by 39 publications

(3 citation statements)

References 6 publications

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“…To overcome the problems related to oscillator-based interfaces, the recently proposed current-mode Wheatstone bridge in Figure 10 a can be used. With respect to the conventional voltage-mode Wheatstone bridge consisting of four resistances, the current-mode Wheatstone bridge [ 85 ] has a smaller number of resistors and employs a current instead of a voltage as exciting input, allowing the produced signals to be processed with current-mode active blocks, which enjoy better performances in terms of high-frequency operation. This idea may be applied both to the CCII and VCII cases.…”

Section: Current-mode Sensor Interfaces For Bioelectrical Signal Cond...mentioning

confidence: 99%

A Survey on Current-Mode Interfaces for Bio Signals and Sensors

Scarsella

Barile

Stornelli

et al. 2023

Sensors

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In this study, a review of second-generation voltage conveyor (VCII) and current conveyor (CCII) circuits for the conditioning of bio signals and sensors is presented. The CCII is the most known current-mode active block, able to overcome some of the limitations of the classical operational amplifier, which provides an output current instead of a voltage. The VCII is nothing more than the dual of the CCII, and for this reason it enjoys almost all the properties of the CCII but also provides an easy-to-read voltage as an output signal. A broad set of solutions for relevant sensors and biosensors employed in biomedical applications is considered. This ranges from the widespread resistive and capacitive electrochemical biosensors now used in glucose and cholesterol meters and in oximetry to more specific sensors such as ISFETs, SiPMs, and ultrasonic sensors, which are finding increasing applications. This paper also discusses the main benefits of this current-mode approach over the classical voltage-mode approach in the realization of readout circuits that can be used as electronic interfaces for different types of biosensors, including higher circuit simplicity, better low-noise and/or high-speed performance, and lower signal distortion and power consumption.

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Section: Current-mode Sensor Interfaces For Bioelectrical Signal Cond...mentioning

confidence: 99%

A Survey on Current-Mode Interfaces for Bio Signals and Sensors

Scarsella

Barile

Stornelli

et al. 2023

Sensors

View full text Add to dashboard Cite

show abstract

“…The CMWB is built with a current‐conveyor 2 (CCII), 13 a couple of

I_{REF 31}

current sources and a diode‐mode NMOS transistor connected between the sensors and ground. This circuit topology is named AZKA cell 14 . The voltage at terminal Y from the CCII is

V_{normalY} = R_{REF} \cdot I_{REF 31} + V_{B},

and the current sourced by terminal X is

I_{X} = \frac{V_{normalY} - V_{normalB}}{R_{SENSE}} - I_{REF 31},

since one of the properties of the CCII is to keep

V_{normalX} = V_{normalY}

.…”

Section: Circuit Designmentioning

confidence: 99%

Low‐power temperature‐independent CMOS measurement circuits for resistive gas sensors

Goyret

Cassani

Carbonetto

et al. 2023

Circuit Theory & Apps

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“…The main challenges in designing CCII can be the distortion introduced by a mismatch of the transistors in the CCII’s current mirror [28, 29] and the requirement for dual voltage supplies which is undesirable in portable systems [30, 31]. There are several reports describing CCII-based sensor interface circuits [32, 33]. Nevertheless, at the time of writing, there are only a handful of papers targeting low-power portable or bio-implantable devices for physiological monitoring [34, 35].…”

Section: Introductionmentioning

confidence: 99%

A current-mode system to self-measure temperature on implantable optoelectronics

et al. 2019

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BackgroundOne of the major concerns in implantable optoelectronics is the heat generated by emitters such as light emitting diodes (LEDs). Such devices typically produce more heat than light, whereas medical regulations state that the surface temperature change of medical implants must stay below + 2 °C. The LED’s reverse current can be employed as a temperature-sensitive parameter to measure the temperature change at the implant’s surface, and thus, monitor temperature rises. The main challenge in this approach is to bias the LED with a robust voltage since the reverse current is strongly and nonlinearly sensitive to the bias voltage.MethodsTo overcome this challenge, we have developed an area-efficient LED-based temperature sensor using the LED as its own sensor and a CMOS electronic circuit interface to ensure stable bias and current measurement. The circuit utilizes a second-generation current conveyor (CCII) configuration to achieve this and has been implemented in 0.35 μm CMOS technology.ResultsThe developed circuits have been experimentally characterized, and the temperature-sensing functionality has been tested by interfacing different mini-LEDs in saline models of tissue prior to in vivo operation. The experimental results show the functionality of the CMOS electronics and the efficiency of the CCII-based technique with an operational frequency up to 130 kHz in achieving a resolution of 0.2 °C for the surface temperature up to + 45 °C.ConclusionsWe developed a robust CMOS current-mode sensor interface which has a reliable CCII to accurately convey the LED’s reverse current. It is low power and robust against power supply ripple and transistor mismatch which makes it reliable for sensor interface. The achieved results from the circuit characterization and in vivo experiments show the feasibility of the whole sensor interface in monitoring the tissue surface temperature in optogenetics.

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AZKA cell, the current-mode alternative of Wheatstone bridge

Cited by 39 publications

References 6 publications

A Survey on Current-Mode Interfaces for Bio Signals and Sensors

A Survey on Current-Mode Interfaces for Bio Signals and Sensors

Low‐power temperature‐independent CMOS measurement circuits for resistive gas sensors

A current-mode system to self-measure temperature on implantable optoelectronics

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