The Potentiostat

Gain-Phase with 100% Ir CompensationA [dB]r + RdlAoRe l + r + Rdlr + Rdl3R d lΦ 011 + pτο1 + pτ′′1+ pτ′1+pτ e1 + pτ′′In an attempt to perfectly cancel out the DC“Ir” error caused by the final valued residual“r” due to the small, but physically present,distance between the Luggin capillaryreference electrode and the investigatedelectrode, the experimenter aims to arrive atthe best possible DC precision byintentionally applying positive feedbackcounteracting the error “Ir” term. This acthowever reshapes the feedback red line insuch an way that the point of intercept Noccurs at a phase angle of 180 0 whichbrings the feedback control system on theverge of stability and in reality the systemloses control breaking into wild oscillationsand destroying any delicate electrochemicalload. In other words the electronicpotentiostat is possibly one of the fewelectronic control systems where DCprecision is directly related to AC stability.