Analogue, Mixed Signal, LSI


Impedance and potentiostat front end

26 June 2019 Analogue, Mixed Signal, LSI

A new electrochemical and impedance measurement front end has been developed by Analog Devices to enable the next generation of vital sign monitoring devices and intelligent electrochemical sensors.

The AD5940 incorporates both potentiostat and electrochemical impedance spectroscopy (EIS) functionality on a single chip, allowing for sensor measurement in both time and frequency domains.

The device features integrated hardware accelerators for advanced sensor diagnostics, ultra low noise for accurate sensor measurements, and is designed for wearable ‘always-on’ applications. Supporting the measurement of 2-lead, 3-lead and 4-lead electrochemical sensors, it is suitable for applications where high-precision biological and chemical sensing is mission-critical, such as industrial gas sensing, liquid analysis, material sensing, vital signs monitoring, impedance spectroscopy and disease management.

The on-chip potentiostat allows for a host of standard electrochemical-based measurement techniques, such as amperometric, voltametric or impedance measurements.

The AD5940 is designed to be used in healthcare-related bio-impedance systems for both skin impedance and body impedance measurements, and also to work with the AD8233 AFE in a complete bioelectric/biopotential measurement system.

The analog front end chip can measure voltage, current and impedance. The device consists of two potentiostat loops: a low bandwidth loop with the ability to generate AC signals up to 200 Hz, and a high bandwidth loop with the ability to generate AC signals up to 200 kHz. The ultra-low power potentiostat consumes 6,5 μA in biased mode.

The AD5940 measurement channel features a 16-bit, 800 kSps, multichannel successive approximation register (SAR) analog-to-digital converter (ADC) with input buffers, a built in anti-alias filter (AAF), and a programmable gain amplifier (PGA).

The ADC features an input voltage range of ±1,35 V; an input mux before the ADC allows the user to select an input channel for measurement. These input channels include multiple external current and voltage inputs, and internal voltage channels. The internal channels enable on-chip diagnostic measurements of the internal supply voltages, die temperature and reference voltages.

The AD5940 measurement blocks can be controlled via direct register writes through the serial peripheral interface (SPI), or alternatively, by using a pre-programmable sequencer, which provides autonomous control of the AFE chip. 6 KB of static random access memory (SRAM) is partitioned for a deep data first in, first out (FIFO) and command memory. Measurement commands are stored in the command memory and measurement results are stored in the data FIFO. A number of FIFO related interrupts are available to indicate the state of the FIFO.

For more information contact Conrad Coetzee, Altron Arrow, +27 11 923 9600, ccoetzee@arrow.altech.co.za, www.arrow.altech.co.za



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Pressure sensor subsystem for sleep apnea applications
25 November 2020, Brabek , Analogue, Mixed Signal, LSI
Superior Sensor Technology’s CP Series sensor module family builds upon the high-performance SP Series NimbleSense architecture. For reference, the SP Series integrates an advanced piezoresistive sensing ...

Read more...
Active GNSS patch antenna
25 November 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
The Taoglas ASGGB184.A is a single-band, active GNSS patch antenna covering GPS, GLONASS, BeiDou and Galileo. With hidden active circuitry embedded between the ceramic patch and PCB base, it has been ...

Read more...
SiC SBDs for automotive applications
25 November 2020, Altron Arrow , Power Electronics / Power Management
As vehicle electrification continues rapid growth worldwide, innovative power technologies such as silicon carbide (SiC) are required for high-voltage automotive systems ranging from motors to on-board ...

Read more...
Out-of-the-box global MTC connectivity
25 November 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
The Thales Cinterion EGX81 Efficient IoT Gateway raises the bar on IoT simplicity, delivering highly efficient global Machine Type Communications (MTC) connectivity straight out of the box. The EGX81 ...

Read more...
Littelfuse launches DC disconnect switch product line
25 November 2020, Altron Arrow , Circuit & System Protection
Littelfuse has expanded its solar product line of fuses, relays, surge protection devices, and more with its new DC disconnect switch. Trusted with over 25 million installations, Littelfuse understands ...

Read more...
Altron appoints new company secretary
25 November 2020, Altron Arrow , News
Nicole Morgan has been appointed as company secretary of Altron with effect from 1 January 2021. An admitted attorney of the High Court with 11 years of corporate law and company secretarial experience, ...

Read more...
MCU module for Bluetooth 5.2 low energy applications
25 November 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
The certified WB2072-00 module from Jorjin is a wireless MCU (microcontroller) module targeting Bluetooth 5.2 low energy applications. It is based on the STMicroelectronics BlueNRG-355AC wireless MCU ...

Read more...
RTLS tag module for real-time positioning
25 November 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
Inpixon announced the launch of its newest smart tag module, the swarm bee LE V3, supporting a range of indoor and outdoor location applications including real-time location systems (RTLS). This is ...

Read more...
The A to Z of A2B applications
25 November 2020, Altron Arrow , Editor's Choice, Telecoms, Datacoms, Wireless, IoT
An A2B device’s support for up to 32 channels of downstream audio and upstream audio on the network facilitate the distribution of multiple channels of different audio content within a single system.

Read more...
Enhanced RF connectors and terminators
25 November 2020, Altron Arrow , Interconnection
Amphenol RF has expanded its SMP product series with enhanced performance connectors and the introduction of terminators. SMP connectors are ideal for telecommunications and military applications which ...

Read more...