Why we use MOS family if BJT has better GAIN or BW?

• Apr 6, 2004

• #1

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tradeoff

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Why we use MOS family?

Hi

I want to know if BJT family has a better behavier (GAIN or BW)
then why we use MOS family?

 

• Apr 6, 2004

• #2

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NTFS

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Re: Why we use MOS family?

HI

Because CMOS and MOS transistrors are very small and we can put a lot of it in a small chip.

 

• Apr 6, 2004

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FoxyRick

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Re: Why we use MOS family?

Much higher input impedance (voltage-driven rather than current-driven) and much lower power required.

Cheers,
FoxyRick.

 

• Apr 6, 2004

• #4

flatulent

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Re: Why we use MOS family?

It is all a matter of cost. Consumers shop for price and not performance. There is an old saying that, "Hay is cheaper after passing through the horse."

 

• Apr 6, 2004

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maxwellequ

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Re: Why we use MOS family?

The MOS transistors are scalable (you can play with its dimensions, for BJT the dimensions are usually fixed) and smaller. In addition, logic gates with MOS are simpler (and smaller…. again). Finally a MOS process is cheaper than a bipolar one.

 

• Apr 6, 2004

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Re: Why we use MOS family?

hi

CMOS transistors are very small so it use in VLSI

 

• Apr 6, 2004

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Edward_2288

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Why we use MOS family?

lower power consumption

 

• Apr 7, 2004

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chengjie1982

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Re: Why we use MOS family?

MOS transistor consume less power,and switch faster than BJT.

It can be large integrated in a single die.

 

• Apr 8, 2004

• #9

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Re: Why we use MOS family?

Hi

The main advantages of CMOS are:

1. From ground to supply swing in output (fom rail-to-rail)
2. High noise immunity
3. Low power consumption
4. More concise chip area due to lower power dissipation




tnx

 

• Apr 8, 2004

• #10

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maxwellequ

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Re: Why we use MOS family?

Well, one should be careful in stating that circuits using MOS transistor will have lower power consumption. While this can be true for digital circuits (in CMOS gates there is no static power consumption), it may not be true in analog circuits, where the larger gm can be achieved by BJTs, for the same current. Moreover faster analog circuits use (almost) always BJTs.

 

• Apr 8, 2004

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manitooo

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Why we use MOS family?

If I can sum up :

CMOS : good for digital
BJT : good for analog

But it's only a general statement 'cause all is possible

 

• Apr 15, 2004

• #12

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abner

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Re: Why we use MOS family?

tradeoff said:

Hi

I want to know if BJT family has a better behavier (GAIN or BW)
then why we use MOS family?

Click to expand...

Cheap and scalable easier

 

• Jun 3, 2004

• #13

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zahrein

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Why we use MOS family?

It is cheaper, smaller and preferable by the industries.

 

• Jun 3, 2004

• #14

brain79

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Re: Why we use MOS family?

when u use CMOS you can work on very small area, the size of transistors can be personalized to your application, high input impedance, the posibility to implement them as conmuted capacitances in to replace resistances, lately they can work on sub-theshold to minimize power consumtion increase noise rejection, etc...

 

• Jun 4, 2004

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Noman Yousaf

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Why we use MOS family?

this family has no critical voltage limit. (3-18Vtyp)
and low power consumption.
i made a circuit using about 35 CMOS ICs.
it took only 1 mA.for all ICs

 

• Jun 7, 2004

• #16

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EEHardware

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Why we use MOS family?

smaller,faster,High noise immunity,Low power consumption

 

• Jun 10, 2004

• #17

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duguzhang

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Re: Why we use MOS family?

Physically speaking, BJT is minor carrier conducting device and CMOS is major carrier conducting device.

BJT has its own advantages such as higher gain and higher current driving capability.

 

• Jun 10, 2004

• #18

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medrano

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Re: Why we use MOS family?

there are a lot of good reasons: it has a simple fabrication, high speed, low static power consumption, a higher integration is posible (there arenot resistive elements -resistive elements require large chip areas in BJT-).

 

• Jun 10, 2004

• #19

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colonel

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Re: Why we use MOS family?

mos TR is mainly used in digital area as its small size and low power consumption

 

• Jun 10, 2004

• #20

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Re: Why we use MOS family?

Well if you look at it purely from a performance standpoint, ie., spped, BJTs win hands down. Their fT is much higher than CMOS. However a majority of todays chips are digital with ~ 20% analog. For use as a switch the MOS transistor works the best. It has zero DC consumption, much smaller and since the late 80's is easier to fabricate.

If it was left to analog design engineers, they woul always go for a Bipolar or atleast a BiCMOS process, because it gives you more options