Single-Lead Heart-Rate Monitor AFE Measures 4 by 4 mm

Weybridge, UK: A low-power heart-rate monitor analogue front end (AFE) is claimed to be the smallest with a single lead, according to developer Analog Devices. The AD8232 AFE is designed for the ECG signal-conditioning requirements of fitness applications and wearable, portable, or remote health-monitoring equipment. The 180-µA device comes in a 4- by 4-mm, 20-pin LFCSP package.

The AD8232’s flexible analogue filtering configuration incorporates a two-pole, high-pass filter that’s tightly coupled with the IC’s instrumentation amplifier architecture. There’s also an uncommitted operational (gain) amplifier that allows 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 analogue domain, the AFE can accommodate electrode dc offsets while operating on a single supply voltage without sacrificing signal quality.

The device also incorporates a reference buffer, right leg drive circuit, and shutdown function. In addition, a user-selectable (ac or dc) leads-off detect circuit monitors when an electrode is disconnected from the patient or user, providing an alert to the system.

Analog Devices