ALLPCB
A white paper titled "ADI wearable solutions for vital-sign monitoring" explains ADI's signal-chain approaches for vital-sign monitoring and lists 20 recommended product examples across optical, impedance, ECG, temperature, motion, and environmental applications to facilitate component selection.
Context and scope
Vital-sign monitoring (VSM) functions are increasingly integrated into phones, watches, earphones, and other smart wearables. These devices can measure a range of vital signs and health indicators, including body temperature, heart rate, respiration, blood oxygen saturation (SpO2), blood pressure, and body composition. ADI aims to support the development of medical-grade wearable devices.
PPG HRM heart-rate measurement
ADPD188GG
For heart-rate monitoring (HRM), ADI offers the ADPD410x multi-parameter chip family and the ADPD188GG module. The ADPD188GG is a production-ready photoplethysmography module that integrates a high-performance optical front end, two LEDs, and two photodiodes. The module optimizes the APD optical design, significantly reducing customer optical-design effort, particularly for engineers who are less familiar with optics.
ECG measurement
AD8233
Dry electrodes and motion introduce new challenges for ECG designs. The AD8233 is a low-power single-lead analog front end (AFE) for ECG and other biopotential measurements. It supports two-electrode and three-electrode configurations and comes in a 2.0 mm × 1.7 mm package. The AFE integrates features such as fast restore, leads-off detection, and shutdown. AD8233 includes internal RFI filtering, enabling easier monitoring of analog signals and subsequent signal processing.
Impedance measurement
AD5940
Impedance measurement applications include bioelectrical impedance analysis (BIA), galvanic skin response (GSR), and electrodermal activity (EDA). ADI recommends the AD5940, a high-precision, ultra-low-power analog front end system designed for skin and body impedance measurement. It excites and measures sensor current, voltage, or impedance response. AD5940 integrates a DAC excitation source and provides two excitation loops: a low-power loop that generates DC to 200 Hz signals for continuous EDA/GSR detection, and a high-performance loop with up to 200 kHz excitation for higher-precision measurements such as body-fat analysis. The digital section includes a dedicated DFT for digital processing. The device is designed to balance power consumption and measurement performance.
Multi-parameter monitoring
ADPD410x (and ADPD4000)
The ADPD410x family is a medical-grade multi-parameter solution intended for wearable products, integrating functions to monitor multiple vital signs simultaneously, such as PPG, SpO2, ECG, impedance, and temperature. The ADPD4000 can achieve up to 105 dB signal-to-noise ratio and integrates eight LED drivers, four of which can be driven simultaneously. Each driver can source up to 200 mA, with a total LED peak drive current of 400 mA. Modern applications increasingly require multiple LED channels—for example, SpO2 measurement needs both infrared and red LEDs, while continuous blood-pressure monitoring may require multiple light sources. Multi-channel LED drivers enable these use cases.
White paper contents
The white paper provides detailed descriptions of the solutions above and includes specifications and recommended application contexts for 20 ADI products across optical, impedance, ECG, temperature, motion, and environmental sensing. The document is intended to help engineers select appropriate components for wearable vital-sign monitoring designs.
