A question about NPN tr layout

[llbaobao]

npn tr basic

I saw some bipolar layout of others, and found that some NPN tr's collectors are drawn like a comb style!

Does it makes some senses to draw the collector of a NPN tr like a comb?

Thanks for any reply!

 

[pranam77]

npn layout

Can you put a link about where it is given?

 

[dick_freebird]

Multifinger devices improve things like overall base
junction area, debiasing (end fed metallization I*R)
and so on.

A collector comb without E, B between them would be
pretty pointless.

Depending on the application you may like a
C-B-E-B-C (minimizing base resistance, like for low
noise) or C-E-B-E-C (minimizing collector resistance
instead).

 

[llbaobao]

Thank you for your reply.

I attach a figure.

there are also other nearly the same comb like collector in the layout.

Is there any other meaning?

 

[snafflekid]

This is a guess, but is this a vertical PNP where the substrate is used as a grounded collector? This fingered area may be p+ connected to ground.

 

[dick_freebird]

That is one crazy looking "transistor".

Perhaps the finger is really a second emitter and the
notching, an attempt to match emitter-base perhipery
as well as area (a simple rectangular scaling, would
not hit both simultaneously). Though my preference
would be to instance-ratio identical polygons if an
integer ratio was the desired outcome).

 

[llbaobao]

The leftmost line is ground line. This is certain.

according to the circuit analysis, the comb like area is collector, that's all.

of course, such analysis maybe wrong.