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Improve EMC Protection While Maintaining Capacitance-to Digital Conversion Accuracy
The AD7746 capacitance-to-digital converter (CDC) measures the capacitance of a floating capacitive sensor directly, that is, the sensor connects directly to the AD7746 input pins. Electromagnetic interference distorts the electric field around the capacitive sensor, thus altering the capacitance measurement. External filtering can be used to protect the AD7746 from this electromagnetic interference, but including filters in the signal path degrades the conversion accuracy. This 20-page Application Note discusses the EMC performance that can be achieved with an external filter on the AD7746 pins as well as the affect of the filter on the accuracy of the AD7746.
Impedance Converter Measures Unknown Impedances
This 5-page Application Note details how to set up the evaluation board for the AD5933 impedance converter, and how to measure the impedance of the on-board 15 pF capacitor. The AD5933 data sheet provides additional information and should be consulted when using the evaluation board.
This circuit is a highly integrated electrocardiogram (ECG) front end for use in battery powered patient monitoring applications. Used in a typical 5-lead (four limb and one precordial chest lead) ECG measurement system, it includes respiration and pace detection. This configuration is typical for portable telemetry ECG measurements or a minimum lead set from a line-powered bedside instrument. A typical ECG signal has 1‑mV amplitude when measured on the surface of the skin, thus requiring measurement sensitivity and noise in the microvolt level. The ultralow noise of the ADP151 linear regulator (9 μV rms from 10 Hz to 100 kHz), coupled with the power supply rejection of the ADAS1000, ensures low overall noise.
Catherine Redmond, Trans-thoracic impedance measurements in patient monitoring, EDN, 2013-02-12
John Kruse and Catherine Redmond, Detecting and Distinguishing Cardiac Pacing Artifacts, EDN, 2013-01-18
John Kruse and Catherine Redmond, Detecting and Distinguishing Cardiac Pacing Artifacts, Analog Dialogue, 2012-11-05
Bob Scannell, MEMS enable medical innovation, EE Times, 2012-10-12
Ning Jia, ADI Capacitance-to-Digital Converter Technology in Healthcare Applications, Analog Dialogue, 2012-05-01
Designing for Vital Sign Monitoring - This webcast provides a detailed analysis of how to design for measuring ECG and heart rate for patient monitoring and sports and fitness applications. A primer will be given on the different topologies for cardiac monitoring, followed by a deep dive into the architecture of the AD8232, finishing with a system level perspective of how it can be used in the various health and sports and fitness applications. Co-sponsored by Arrow NA.
Healthcare Webcast: MEMS Inertial Sensors in Healthcare Designs - In this webcast you will learn the basics on MEMS motion sensing including architectures and technology including accelerometers, gyroscopes, and IMUs. Applications explored include precise positioning/tracking of healthcare scanning equipment, surgical tool guidance, balance and control of prosthetics, and motion sensing.
Healthcare Webcast: Optimizing Ultrasound Systems using Integrated Receivers - In this webcast TGC noise analysis techniques will be presented to aid designers in determining receiver noise contributions in near and far field B mode imagining. The key IC performance specifications that determine PW Doppler mode sensitivity will also be discussed, as will analysis of the CW Doppler signal path critical noise sources and suggested filtering techniques will be presented.
Healthcare Webcast: Simplifying Point-of-Care Patient Monitor Design Using ECG AFE - This webcast will introduce an ECG Analog Front End (AFE) which integrates the functional blocks traditionally designed into an ECG system using discrete components, as well as respiration measurement and pace pulse detection. We will look at how this device addresses some of the main ECG design challenges including critical system level requirements.
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