# Transfer function and bode plot of an op-amp circuit

Given is a op-amp circuit which has to be solved using the nullor model to find the transfer function as shown below: Using the nullor model of an ideal op-amp I tried to find the transfer function and plot frequency and phase response graphs. I change variables and indexes to a more common used once. The resistor R1 has no effect as there is no current and no voltage drop.

As I don't know if this can be even built I have know idea if this is correct or if this is more a theoretical approach in order to use the nullor model. The original circuit using an op-amp with this forth input at the bottom of the op-amp symbol which only shows that the nullor model has to be used. I couldn't find any thing similar to that symbol and it seem like that only my professor uses it which doesn't really help.

• Two questions: (1) Where are the supply voltage(s)? (2) Opamp with voltage output or OTA with current output (note the current source symbol in the 2nd figure)? – LvW Sep 5 '15 at 14:56
• @LvW: Vs is the supply voltage and can be of any kind but not further clarified and it is a Op-amp with voltage output. The current source symbol is used as the open loop voltage gain is infinite. The nullor model uses the nullator and norator for ideal op-amps. I just drew the op-amp triangle around it so it is clear where I used the nullor. – Phil Sep 5 '15 at 15:45
• The voltage source is just not drawn with its circle symbol. – Phil Sep 5 '15 at 17:22
• Ideal opamps have no supply voltages, and they can source infinite amounts of current, and have infinite voltages. They also have no noise, no offset and and no bias current. – Voltage Spike Mar 8 '16 at 18:01