An EMG readout front-end with automatic gain controller for human-computer interface

We propose an electromyogram (EMG) readout front-end with an automatic gain controller (AGC) for a human-computer interface (HCI). The proposed AGC adaptively controls voltage gain depending on the amplitude of the extracted EMG signal, which is varied according to the number of muscle fibers and the surface condition of the skin. Furthermore, the AGC alleviates the resolution requirement of an analog-digital converter (ADC) by fitting the maximum amplitude of the EMG signal to the full input range of the ADC. In order to obtain the wide-gain range, two variable gain amplifiers (VGAs) are used in the AGC. The voltage gain of the AGC is adjusted from 0 to 48.2 dB. A digital gain controller is employed to reduce the power consumption of the AGC. The calculated power efficiency of the AGC is 6.51 dB/μW. The proposed readout front-end is fabricated by using a 0.18 μm CMOS process technology and dissipates 19 μW at the supply voltage of 1.5 V.