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Op-Amp uA741 with high gain

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eezatiee

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hi all,

I just want to ask, how to design an op-amp with high gain.
I need an increasing about 50% of DC gain. However, at the same time the supply current
must be reduced about 30%.

Thank you. I hope to get any ideas from you all.
 

eezatiee said:
hi all,

I just want to ask, how to design an op-amp with high gain.
I need and increasing about 50% of DC gain. However, at the same time the supply current
must be reduced about 30%.

Thank you. I hope to get any ideas from you all.
Click to expand...


Hi,
I think you can use 2 stages or 3 stages for your op design, and use the cascode structure.
This will satisfiy your taget.

Best regards
Crossbow
 

thank you..

Is there any reading material?

Actually, i try to reduce the current supply by increasing the resistance, but don't know how to increase the DC gain at the same time.

Can i also know how to calculate the phase margin?
 

eezatiee said:
hi all,

I just want to ask, how to design an op-amp with high gain.
I need and increasing about 50% of DC gain. However, at the same time the supply current
must be reduced about 30%.

Thank you. I hope to get any ideas from you all.
Click to expand...

If bandwidth is not a concern, it can be easily achieved as output resistance is inversely proportional to biasing current.
 

You senstence is interesting. You want increase the gain and cut power at the same time. Actually, you have not specify what you are currently in your design. If you currently have dc gain 40dB and want increase to 60dB. It is easy. But if you are look for 120+ dB gain. It is much more difficult. You can read some opamp book and study high gain opamp design.
 

eezatiee said:
thank you..

Is there any reading material?

Actually, i try to reduce the current supply by increasing the resistance, but don't know how to increase the DC gain at the same time.

Can i also know how to calculate the phase margin?
Click to expand...


I think you may read "Design of Analog CMOS Integrated Circuits" for Behzad Razavi
 

kwkam said:
You senstence is interesting. You want increase the gain and cut power at the same time. Actually, you have not specify what you are currently in your design. If you currently have dc gain 40dB and want increase to 60dB. It is easy. But if you are look for 120+ dB gain. It is much more difficult. You can read some opamp book and study high gain opamp design.
Click to expand...

Thank you.
Currently the gain is 113 dB. From that, I have to design with improvement of 30% gain. The supply current is about 1.2mA and need to be decreased about 30%.
One more thing, the phase margin target is 60 degrees.
I would like to know the easiest way to calculate the phase margin.
 

eezatiee said:
kwkam said:
You senstence is interesting. You want increase the gain and cut power at the same time. Actually, you have not specify what you are currently in your design. If you currently have dc gain 40dB and want increase to 60dB. It is easy. But if you are look for 120+ dB gain. It is much more difficult. You can read some opamp book and study high gain opamp design.
Click to expand...

Thank you.
Currently the gain is 113 dB. From that, I have to design with improvement of 30% gain. The supply current is about 1.2mA and need to be decreased about 30%.
One more thing, the phase margin target is 60 degrees.
I would like to know the easiest way to calculate the phase margin.
Click to expand...

What is the minimum supply voltage?
What is the minimum bandwidth?
All of them help to decide what topology should be used.
 

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