Design Of Instrumentation Amplifier For Portable ECG Signal Acquisition Systems

There is a high demand for portable biopotential signal acquisition systems for the efficient diagnosis of patient’s illness at low cost, low size and also with low power consumption to overcome the today’s ever increasing cost of health care centres. So we are going to design an ASIC for the portable ECG monitoring systems in which Instrumentation Amplifier(IA) is vital in deciding the power consumption and quality of the extracted signal of ASIC. Here in this work we are presenting a chopper modulated two stage(TC-TI) Instrumentation Amplifier which extracts the signal of our interest with high signal quality by eliminating the highly dangerous low frequency flicker noise, DC electrode offset and also provides high CMRR by reducing the effect of common mode signals in the small size. This two stage(TC-TI) IA is very useful when we have more number of parallel signal paths in the ASIC for different features extraction then it significantly decreases the size and power consumption of the ASIC by eliminating the use of single IA for each signal path. To remove the low frequency noise or flicker noise (1/f noise) generated by the circuit we have implemented the technique of chopper modulation and to remove the DC offset generated by the electrodes we have implemented the DC servo loop in the feedback loop which provides the high pass filter characteristics for the IA. Because of chopper modulation spikes appear on the output signal, so to remove those spikes we are using a chopping spike filter(CSF). Finally, to improve the gain further we have implemented simple a gain stage and it’s gain depends on the ratio of the capacitors. In this work we have implemented the IA which can filter the differential electrode offset(DEO) up to 50mV and it provides a CMRR of 150dB with very high input impedance with a powerconsumption of 7.2W