princerock
Junior Member level 2
I am doing a op amp design as my first analog project and encountered many problems
1. I made a diff pair plus cascode as my first stage. It has a gain about 50dB according to simulation. However, the bandwidth is very small. The gain drops to 0dB when the frequency is 1MHz. Then how to increase the bandwidth?
2. When I plus a second stage to this circuit, the gain drops dramatically even if it is a simple CS in the second stage. I just connect the output of the diff pair to the gate of the transistor in the second stage directly. Is this right?
3. As it shows in the schematic, I am using a ideal current source. How can I replace it with some transistors?
4. Please point out other problems exists in my schematic.
Please give me some suggestions. Or in which book can I find the solutions to these problems? Thank you very much!
1. I made a diff pair plus cascode as my first stage. It has a gain about 50dB according to simulation. However, the bandwidth is very small. The gain drops to 0dB when the frequency is 1MHz. Then how to increase the bandwidth?
2. When I plus a second stage to this circuit, the gain drops dramatically even if it is a simple CS in the second stage. I just connect the output of the diff pair to the gate of the transistor in the second stage directly. Is this right?
3. As it shows in the schematic, I am using a ideal current source. How can I replace it with some transistors?
4. Please point out other problems exists in my schematic.
Please give me some suggestions. Or in which book can I find the solutions to these problems? Thank you very much!