Research And Design Of Portable ECG Signal Acquisition Circuit

In recent years,biomedical chips have become a research hotspot in the field of integrated circuits.As an important part of biomedical signal detection system,the performance of bioelectrical signal acquisition analog front-end circuit directly affects the accuracy and effectiveness of the whole system.By analyzing the characteristics of ECG signals and the characteristics of patch electrodes,this thesis designs a portable front-end circuit for ECG signal acquisition with portable,low power consumption and low noise.The analog front-end circuit of ECG signal acquisition designed in this thesis mainly includes instrument amplifier,operational amplifier,right leg driver amplifier and bandgap reference current source.An indirect current feedback architecture is adopted in the instrumentation amplifier,and a differential folded cascode structure is used as the core circuit.A complementary CMOS input pair is applie as the input pair to achieve a rail-to-rail common-mode input range,improve power utilization and reduce external noise interference.In addition,a Sallen-Key topology is adopted in an operational amplifier to reduce the amplitude of the ECG caused by the acquisition environment and the individual acquisition.The gain is 2.5 times by changing the adjustable resistance.The stepping is evenly adjustable.In order to further improve the common mode rejection ratio of the system,this thesis designs a right leg drive circuit with integrator function and a bandgap reference current source circuit with temperature compensation to provide stable bias current for the main body amplifier circuit.The circuit and layout design of the proposed ECG analog front-end circuit is based on 0.18 ?m CMOS process.The simulation results show that the designed ECG analog front-end circuit has a total current of only 120 ?A,a bandwidth of 0.43 Hz ~ 43.91 Hz,a maximum gain of 60.83 dB and adjustable gain,which can suppress the ECG electrode offset voltage of 300 mV.The equivalent input noise of the ECG analog front-end circuit is 3.5 ?Vrms,and the layout area is 1.3 mm × 0.84 mm.The performance of the ECG analog front-end circuit basically meets the requirements of ECG signal acquisition.