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Design >> Analog Design >> Hi, all
https://designers-guide.org/forum/YaBB.pl?num=1177584554

Message started by Julian18 on Apr 26^th, 2007, 3:49am

Title: Hi, all
Post by Julian18 on Apr 26^th, 2007, 3:49am

Can anyone here tell what is the size consideration in design MOS current mirror? should I must use equal length? why? what 's the principle when i am choosing the width of the transistor? Could anyone shed some light on this ???

TIA.

Julian

Title: Re: Hi, all
Post by Julian18 on Apr 26^th, 2007, 7:11pm

hi, any suggestions here?

Thanks

Title: Re: Hi, all
Post by sheldon on Apr 28^th, 2007, 6:39am

Julian,

It is difficult to answer the question without context,
that is, what is the intent of your question? Are you
looking for guidelines for best matching? Do you need
to increase the output compliance? Do you need to
minimize the saturation voltage?

In general, it seems like the rules would be something
like,
1) Match length
2) Match finger width
3) For high impedance, increasing gate length can help
4) However, it is better to use a more complex mirror
design to increase impedance, for example, cascode
or gain boost

Best Regards,

Sheldon

Title: Re: Hi, all
Post by zilinhust on May 6^th, 2007, 8:16pm

you can read Allen's book-analog CMOS design

doing hand calculation,fist