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Fig. 6 | Journal of NeuroEngineering and Rehabilitation

Fig. 6

From: A high-performance 8 nV/√Hz 8-channel wearable and wireless system for real-time monitoring of bioelectrical signals

Fig. 6

Total harmonic distortion + Noise (a) and third order intermodulation distortion (IMD3) (b) of the proposed instrument’s AFE (gain = 60 dB). (a) Taking into consideration that the available dynamic range of the AFE is from 1 μV peak to 2.3 mV peak, it is clear that the achieved THD + Noise is less than 0.3%. (b) The two tones applied to the AFE of the proposed instrument were f1 = 4.9 Hz and f2 = 5.1 Hz. The output power of a single fundamental tone (in dBm - red line in the graph) and the relative power of the IMD3 products referenced to a single tone (blue circles) are plotted against the applied input power. The third-order intercept line (dashed blue line) is extended to intersect the extension of the fundamental output signal line (dashed red line). This intersection is termed the third order intercept point IP3. The calculated IP3 exhibits a relatively high value, which is desired, since the higher the IP3 value the better the linearity of the amplifier and the weaker the output intermodulation products that will be generated at the amplifier’s output

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