Monitor is a kind of medical equipment used for patients to continuously monitor patients'vital signs.By collecting physiological parameters such as heart rate,blood pressure and blood oxygen saturation in real time,it is transformed into intuitive waveforms and values,which helps medical staff to quickly judge patients'conditions.To achieve accurate acquisition,high-performance ECG analog front-end is indispensable.As a highly integrated bioelectric signal acquisition solution,AFE956 is attracting more and more attention from medical equipment manufacturers,and can even replace ADAS1000 of ADI,making it an ideal choice for 12-lead and 18-lead ECG monitors.
 

 

　　AFE956,an analog front end,belongs to AFE95x series.It is a multi-channel,synchronous sampling 24-bitΔ-σanalog-to-digital converter(ADC)with a programmable gain amplifier(PGA),an internal voltage reference and an on-board oscillator.It covers almost all functional modules required for the application of medical electrocardiogram(ECG)and electroencephalogram(EEG).Each channel of AFE956 is equipped with a flexible input multiplexer,which can be independently connected with internal test signals,temperature sensors or lead drop detection circuits.At the same time,the lead disconnection detection can be realized inside the ECG analog front end by pulling up/down resistors or exciting current sources without additional components.The three amplifiers built in the analog front-end can also generate the Wilson Center Terminal(WCT)required by the standard 12-lead ECG,which further improves the integration.
 

 

　　The ECG analog front-end AFE956 adopts 6-channel design,each channel contains low-noise PGA and high-resolution ADC,and supports multiple working modes:high-resolution mode,low-power mode and so on.In the low power consumption mode,the power consumption per channel is only 0.76mW,which is very suitable for portable or bedside monitoring equipment.In terms of signal quality,the ECG analog front-end AFE956 performs well.The noise introduced by the input is as low as 4Vpp(bandwidth of 150 Hz,gain of 6),the input bias current is only 100pA,and the common mode rejection ratio(CMRR)is as high as 120dB,which ensures that the weak ECG signal can be stably collected in complex environment.Programmable gain supports 1,2,3,4,6,8,12 or 24 times,which can flexibly adapt to different electrodes and signal intensities.
 

 

　　The AFE956 is highly compatible with ADI's ADAS1000 in function and performance,and supports SPI serial interface and daisy chain,which is convenient for directly replacing or upgrading the existing design.For developers who are looking for ECG analog front-end,AFE956 not only provides a complete analog front-end scheme,but also helps the next generation of medical monitoring equipment to land quickly with lower power consumption,smaller size and higher integration.


Keywords:analog front-end