I have a question AD8233.
AD8233 Evaluation board UG-1016 written,
A lower common-mode signal cutoff frequency improves RFI rejection; however, it can increase the risk of instability with a right leg drive feedback loop.
Content of consultation
· Please explain concretely the relation between the cutoff frequency and the feedback loop.
· Please tell us about the characteristics of the OP amplifier used for the integrator.
· Please tell me about calculation method of loop gain. ? (We are asking you because the notes on loop gain are stated in the data sheet of AD8233)
· The values of R36 and R42 were increased to improve the static tolerance.
Since it is on the order of kHz as the cutoff frequency, it is judged that the signal component is not affected
· In fact it is discovered that the waveform is affected
Waveform at 47 kohm (Raw filter)
Waveform at 180kohm (Raw filter)