Electronics 3c - Op amp examples

Question 1

Derive the voltage out of this circuit.

Answer 1

Question 1

Derive the transfer function of this circuit.

Answer 1

Question 2

Derive the transfer function of this circuit.

Answer 2

Question 3

What are the practical considerations for op-amps that effect the derived functions compared to reality?

Answer 3

• Bias currents: are present in BJT based op-amps, so small currents are present in the op-amp. This current is usually very small, pico level.
• Input voltage offset: The voltages may be offset due to precision of the manufacturing of semiconductors. Therefore we can correct this by putting some offset into some of the pins
• Slew Rate: The fact that voltage can’t instantly change to zero because of the capacitors in the transistors. Not unless unlimited current is supplied which will brake is, so there will be some slight slope to the Vout graph.
• Frequency response: gain is affected by frequencies.