A discussion about circuit design from a general point?

Hi, All

I hope the discussion will be a long run.

There are too many different circuits , we can not learn it one by one.

But I think some basic parameter will give us gerneral "feeling", the

feeling what we want to have is about large signal feature, small signal

feature, or time domain feature and frequency feature. I think we can

get all these by a few basic parameters, node gm, node voltage swing,

node Rout and node capacitance .

Do you think that is true? If that is true , how do you get these

parameters?

Thanks

No people care about this topic?

I think it is very important for the designer to

impove from the beginner to the senior.

Let's talk about that!

Hi,

Are you talking about models. This what is attempted by all text books.

For discrete components it is easy. In Analog IC the layouts are innumerable and I dont think it is practical to tabulate these.

BR
M

Hi,brmadhukar

I am talking about analog circuit design , not model or layout.Basicly, I am trying to find a way to get
thorough understanding for different circuits so that
I can analyse the circuit I did not meet before.

B.R.

Hardings

This is more of an artistic area which is hard to describe. Here are some things I do. First, you calculate the DC bias points to see if the transistors are in the linear, cutoff, or saturation regions. This can be done in your head since exact values are not needed at first. Then you look at the signal flow directions for individual transistors, then pairs, then threes and so on so you can get an idea of where the signal comes in and goes out and gets fed back. This gives you an idea of the function of the circuit. Then you calculate the gain of each stage in your head (no exact values are required at first). Next you can get the lower and upper cutoffs by the series and shunt capacitances. Look for impedance levels. Emitter followers indicate low and fet indicate high levels. Look for special circuit elements like tuned circuits and complex RC networks that can be notch filters. At this stage you have a good idea of what the circuit does and you can do more exact calculations with more complex models on paper. In no case should you use a CAD program as a substitute for thinking and understanding. CAD programs should only be used as a second opinion to check your understanding for errors and also to get second order effects.