Biomedical Engineering Reference
In-Depth Information
FIGURE 5-35
Instrumentation op
amp with ground
reference electrode.
FIGURE 5-36
First-order
high-pass filter
followed by further
amplification.
At this stage, the EMG signal should have the features shown in Figure 5-37. Its
frequency content should vary between 5 Hz and 300 Hz, and its amplitude should vary
between 5 mV and a maximum of about 5 V.
The next step in the process is to extract the envelope of the EMG signal. A simple
rectifier diode requires a turn-on voltage of 0.7 V, which is larger than a good proportion of
