Hello,
I'm trying to implement a single supply emg using an INA33 and DRL feedback to reduce noise.
From my understanding, a DRL will sense the CM voltage, buffer it, invert it with some gain and feed it back in the form of a reference electrode. Also, I am aiming for the reference electrode to also provide the CM bias of Vcc/2 to ensure the inputs will be in the CM voltage range. Note that in the schematic i have replaced a TLE2426 voltage splitter with an equivalent separate supply as I was getting difficulties getting the simulation to work.
In practice, I am able to get an EMG signal from this circuit (and some BPF - not shown) using three electrodes: Pos, Neg and REF. However, I usually get about 50 mVpp of 50hz noise. The strange thing is, if I additionally also ground myself, i.e. touch a ground node with my body, the signal quality improves quite noticeably, and I get < 20mVpp of noise. Does this mean I should use four electrodes - POS, NEG, REF, GND or have I done something incorrectly in this circuit?
