Want to understand matching

[Analog_IC]

Can somebody explain about matching in analog circuit design?
I donot know even a bit about this so needed detailed document.

 

[IanP]

There are several sites where you can find info on analog+matching.
One of them you can find here:
**broken link removed**

 

[flatulent]

There are all sorts of passive networks that can change one impedance into another. The audio transformer is one example. Pi and T LC networks can also change the phase angle.

Matching is a special case of impedance transformation where the new impedance is what you want. That is, you design the network to get the desired results. The network may very well produce some other impedance at frequency ranges you are not interested in.

 

[flushrat]

This is a good paper about mismatch, although a little old.
"Characterisation and modeling of mismatch in MOS transistors for precision analog design" JSSC1986
Is there any recent good reference about mismatch and match of .18 .13 process?

 

[Analog_IC]

thanks.
can you write brief about transistor matchig in analog circuit design. this will help in further study.

 

[ambreesh]

Dear Analog_IC,
Razavi, Paul Gray, Baker allen Holberg all have written in their books on this.
I suggest you go through that. It helped me.

 

[dream_taker]

Ion implantation will be uniform if we do matching. Imagine u have sAddBssBddAs then ion implant is done in an inclination angle. So source/Drain will have different ion implant. But using matching we can reduce this difference.

s --> source
d -->drain
A --> transistor 1
B -->transistor 2

Refer Alan Hasting to get more detials.

 

[abhigopal]

refer baker , li, boyce. good book for analog circuit design. it has 2 volumes ..

 

[paladinzlp]

I think the diff-AMP 's input MOS and load MOS 's match is the best important.

 

[Tianlei]

you can find the information/formula in Razavi and R.G. Meyer's analog book.
Matching can be improved in circuit design and layout.
In circuit design,
For current mirror, increasing overdrive voltage will improve matching
For diff AMP, Reduce override voltage will improve matching

In layout
Matching need proper layout, you can refer to "the art of analog layout"

 

[yeewong_su]

Can somebody explain about matching in analog circuit design?
I donot know even a bit about this so needed detailed document.

a good paper for you to ref

 

[Analog_IC]

First of all I need to understand what is matching.......
Do u mean impedance matching ... transmission line theory... How does it come into picture in MOS circuit design.. Ofcourse i know it is important in layout...

Thanks

 

[Vamsi Mocherla]

Dear Analog_IC,

Firstly, lets look into the fact that in a process, there are many variations in the wafer and in the diffusion. Because of these things, things like threshold voltage, mobility, diffusion resistance, bulk coefficient vary. Most importantly in the analog circuits you do not want the above because you are operating with real voltages and currents. We model these variations as the X-axis and Y-axis changes. In order to cancel these effects, we distribute the transistors(which are critical) in such a way that the mean variations cancel each other. Some of the common matching techniques are common centroid, interdigitization, etc.

 

[Analog_IC]

Thanks vamsi and all...