A low-noise front-end amplifier for biopotential recordings

Abstract

We have designed and implemented a multi-channel front-end amplifier in our laboratory to support recording of different biopotential signals. We focused on the design of a system to support simultaneous recording of intra-muscular and surface Electromyographic (EMG) signals. Simulations and laboratory experiments indicated an input rms noise level of max. 288 nV and 590 nV for 20 Hz-1 kHz and 20 Hz-4.5 kHz bandwidth with shorted input. This system supports input voltages up to 49.3 mV peak-to-peak. Excellent gain accuracy for different channels was obtained by avoiding most of the external components to set the gain of the instrumentation amplifiers. Reduction of the power line interference was obtained by amplifying the signal near the electrode and shielding the cables, connectors, and amplifier boxes. Power consumption was reduced to use full-battery powered system, a simple but powerful acquisition strategy that enabled us to provide the flat noise spectrum and the possibility of extending the number of channels up to 105 with the sampling frequency of 10 kHz with only one Serial Peripheral Interface (SPI) line to the USB controller. © 2009 Springer-Verlag.