A 0.18μm front end for ECG/EEG/neural sensor interface

A 1.8V 0.18μm CMOS analog front end consists of a chopper stabilized low noise preamplifier, a capacitive negative feedback gain stage and a variable gain amplifier with digital tunable low pass filter bank is presented. With optimized gain distribution, the analog front end eliminates the 1/f noise by chopper stabilization without the DC offset cancellation servo loops in conventional chopper amplifier, combines the advantages from chopper stabilization and capacitive negative feedback to achieve both low 1/f noise and compact structure. The simulation results show that the proposed analog front end achieves 32nV/Hz^1/2 input referred thermal noise floor with 1.8μA total current from a 1.8V supply, 20kHz chopping frequency, and in-band gain of 400 and 2000, is suitable for electrocardiograph, electroencephalograph, and neural spike recording applications.