Analogue front end creates ‘ecg on a chip’
1 min read
In a move to meet power consumption and cost effectiveness demands from medical equipment developers, Analog Devices has launched the ADAS1000, an analogue front end that is said to simplify the design of five electrode electrocardiogram (ecg) systems. Using the device reduces the signal chain bill of materials from 50 components to the ADAS1000 plus 'a handful' of discrete components.
Jan-Hein Broeders, pictured, healthcare business development manager, Europe, said the diagnostic quality device was not only scalable, but also integrated a number of major system blocks, including pace pulse detection, respiration monitoring, shield drive for long leads, and digital filtering. It also features right leg drive. "With an ecb, you're measuring a signal of 1 or 2mV against a 300mV offset. If you apply gain to the signal, you also gain the offset." The solution is right leg drive, which uses a common mode amp to actively cancel interference.
The data converters in the five channels in the ecg path can run at user selectable speeds. "At 2kHz, they have an enob of 20," said Broeders, "but resolution decreases to 16bit at 128kHz." Should the design require more than five leads, a second ADAS1000 can be cascaded. Broeders added that diagnostics is not the main target market. "If we made a 12 lead part, we would be stuck with one application. With the five lead part, we can make smaller devices at lower cost." In this way, the ADAS1000 can be designed into diagnostic electrocardiographs, bedside patient monitoring systems, Holter monitors and cardiac defibrillators.
Power consumption with all five leads enabled is 19mW, making the part suitable for use in battery powered devices.
