**broken link removed**
Since opamps using the inverting configuration have a built in 180° lag, I would think that at low frequencies, the opamp would just drive the output to the open loop gain lagged 180° since the gain at low frequencies would just be -(Z2/R1), in which Z2 goes from infinity to a decreasingly large number from DC on.
However, the book I am reading is saying that this configuration STARTS with a lag of 270° due to the pole at the orgin. It says the pole at the origin causes an additional 90° of lag at low frequencies. Does anybody mind explaining to me why this is and why I don't see this when I simulate this circuit? Am I doing something wrong or just not understanding?
Bode plot I came up with from simulation is attached. R1 = 1k, R2 = 14.7k, C1 = 2nF, C2 = 220pF
Since opamps using the inverting configuration have a built in 180° lag, I would think that at low frequencies, the opamp would just drive the output to the open loop gain lagged 180° since the gain at low frequencies would just be -(Z2/R1), in which Z2 goes from infinity to a decreasingly large number from DC on.
However, the book I am reading is saying that this configuration STARTS with a lag of 270° due to the pole at the orgin. It says the pole at the origin causes an additional 90° of lag at low frequencies. Does anybody mind explaining to me why this is and why I don't see this when I simulate this circuit? Am I doing something wrong or just not understanding?
Bode plot I came up with from simulation is attached. R1 = 1k, R2 = 14.7k, C1 = 2nF, C2 = 220pF