How to deal with the current source in amplifer?when tapeout

I design a sinple amplifer?

In bias circuit there is a current source to supply the bias current for the main amplifer?

And now I want to tape out this amplifer.

Here comes a question? How to deal with the ideal current source?

Do I make a bandgap circuits to produce the source current?

Or there is other simple implementation?

Thank you!

Re: How to deal with the current source in amplifer?when tap

You need some sort of current source, such as a supply independent, PTAT, or temp. independent source. These can be found in any analog IC text.

Re: How to deal with the current source in amplifer?when tap

One of typical current mirrors is enough, I think.
What kind of amplifier is it? Common source?
a.

Re: How to deal with the current source in amplifer?when tap

Firstly, you generate a current souce using bandgap PTAT sturcutre. And then you layout a current mirror near the current source, and then you let the current flow to the amplifier, which may be far away from the PTAT current source.
Remember, don't let the voltage run a long way, because that will make errors to the current you want.

Re: How to deal with the current source in amplifer?when tap

a good and simple scheme is a constant-transconductance bias circuit, you can refer to David A. Johns and Ken Martin - Analog Integrated Circuit Design - chapter 6
it need connect a external resistance and adjust the resistance to attain the desired current

That depends on how precision the current you want to generate. Bandgap mehod is more precise than const-GM method. But it costs much area.

Hi Booser,

When u ask this question, i think you are not familiar with analog design since everyone designed an op-amp should be able to design a current bias to do final work. Now, you don't know how to design a current bias, it means you are not familiar with analog design, I do think your op-amp will not be working definitely, to be honest.
I would recommend you sit back and study more on your amplifer one more month to make sure you know what is current bias and how it interact with your amplifier. It would be a bad feeling if you finally see your circuit not working in this way.

OK. to answer your question, I think your op-amp is not complex, so just a simple resistive load current source is enough, though this current bias varies with PVT. Careful sizing can be enough for your deisgn.
Forgive me that someone introduce bandgap or PTAT current source for him, I don't think at this moment he can deal with such design as those bandgap designs are even more difficult than what he is now doing. just a simple resistor load current mirror is good enough for his trial

Re: How to deal with the current source in amplifer?when tap

In the question there is nothing about Operational Amplifier. The question is about a simple amplifier. It is obvious that a real current source is needed in any simulation. A.