Date: 09/08/2012

AFE for ECG signal conditioning in wearable health devices

Analog Devices (ADI) has introduced a low-power, single-lead, heart-rate monitor analog front end (AFE) for a wide range of vital sign monitoring applications. The advantage of AD8232 AFE over the other similar products in the market is, AD8232 AFE is 50 percent smaller and uses up to 20 percent less power than competing solutions, as per ADI.

AD8232 AFE is designed specifically to meet the ECG signal conditioning requirements of emerging fitness, portable/wearable monitoring and remote health monitoring equipment. AD8232 incorporates a two-pole, high-pass filter that is tightly coupled with the IC’s instrumentation amplifier architecture, and an uncommitted operational (gain) amplifier that enables the user to employ multi-pole low pass filtering techniques to remove line noise and other interference.

By performing large-gain and high-pass signal conditioning in a single stage in the analog domain, the AD8232 can accommodate electrode DC offsets while operating on a single supply voltage without sacrificing performance or signal quality.

“There is a growing demand for fixed, portable, and even wearable heart-rate monitors that provide vital sign measurements for athletes in training, home fitness equipment or remote health monitoring,” said Patrick O’Doherty, vice president, Healthcare Segment, Analog Devices. “This level of non-diagnostic monitoring is subject to a unique set of design considerations, and ADI believes the AD8232 offers manufacturers a better partitioned, more balanced signal processing architecture with greater flexibility in terms of back-end component selection and filter design. This will translate into system designs that are easier to design, more reliable and more accurate than existing solutions.”

The AD8232 heart-rate monitor AFE also incorporates a reference buffer, right leg drive circuit and shutdown function. The AD8232 also includes user-selectable (AC or DC) leads-off detect circuitry that monitors when an electrode is disconnected from the patient or user, providing an alert to the system. This new heart-rate monitor AFE offers fast-restore mode to quickly and automatically recover the cardiac signal in the event a user temporarily loses contact with an electrode during exercise, or other activity.

AD8232 Heart Rate Monitor Key Features
Supply current: 180 µA
4-mm x 4-mm, 20-pin LFCSP package
2-pole adjustable high-pass filter
3-pole adjustable low-pass filter and gain amplifier
AC/DC Leads-off detection and fast-restore mode
Noise: 20-µVp-p (0.5 Hz to 40 Hz)
Common-mode rejection ratio: 80 dB (DC to 60 Hz)
Integrated Right Leg Drive
2.0 to 3.5V supply voltage range
2.0 to 3.5V supply voltage range

Product Sample Availability Full Production Price each per 1k units Packaging
AD8232 Now August 2012 $1.36 4-mm x 4-mm 20-pin LFCSP