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The differences between BJT and CMOS

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Old Nick

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Hi,
I'm looking for some bullet points on CMOS vs Bipolar technologies for use in analogue signal processing (mixers, amplifiers etc). Such things as bipolar providing better matching, different current consumptions, noise performance etc.
Can anyone give a list of some of the main differences.

Cheers,

Nick
 

Re: bjt vs CMOS

Look

Analog Design Essentials by Sansen
 

    Old Nick

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Re: bjt vs CMOS

cheers,

That's the first book I've seen which actually has a comparison between the two. Normally BJT's and MOS devices are dealt with seperately. Very useful!

Is that the same Sansen from the Laker and Sansen book? (my least favourite analogue book!)

Cheers.

Nick
 

Re: bjt vs CMOS

CMOS is certainly the cheapest, so it is pretty much what most of the designers use. BJT is faster, less noisy, but much more expensive.
 

Re: bjt vs CMOS

Sadegh.j said:
CMOS is certainly the cheapest, so it is pretty much what most of the designers use. BJT is faster, less noisy, but much more expensive.

Hi,

Cheers, but I'm more looking for stuff on matching etc. I'm writing some stuff on CMOS camera's we've made and need to include a section on how some aspects of our design could be improved by using a biCMOS etc technology. i.e. some mixers we used in a camera (modulated light and I/Q demod), were poor due to issues with processing (matching etc.).
My only experience with using BJT's is theoretical (during my degrees), and you commonly here about them being superior in terms of noise and speed, but little is ever explained why. What noise sources (johnson etc.) are lower in BJT's and why. How does the noise improvement change at varying current levels, i.e. the output drive of an op-amp.

I'm sure our foundry charges only about 25%-30% more for that technology, and for the quantities of chips we produce that isn't such a big deal

cheers,

Nick
 

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