Some discrete design questions

Hi All,

I am not familar with discrete design.

Usually, in CMOS digital desgin ( tsmc / umc .. ), I will choose minimum length of MOS, and then adjust the width to meet the requirement.

Now, I am doing some discrete jobs.

If I choose .35u / .25u / .18u for length, is that still normal for discrete ?

Sometimes, I have to use very low value of resistor, in IC design, I just layout some metal.

In discrete, is that still normal to buy 5ohm, 10ohm, 30ohm components?

In fact, I only design CMOS in VLSI level, but I saw a lot of biopolar here, if I still used to use CMOS to design circuit, is that normal?

Best regards, Boki.

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No, normally we choose parts from a manufacturer's list, using their part datasheets as a guide. These don't specify W or L.

We buy parts in standard catalog values, such as 4.7 ohms, etc.

We use bipolar, or MOS and CMOS, as is best appropriate and available. But again, boki, we don't use biopolar. :-)

    - Win
Reply to
Winfield Hill

Hello Win,

Some do:

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Regards, Joerg

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"Frozen organic"? I didn't know they could freeze shit ;-)

...Jim Thompson

|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Geometry size is not typically stated for discrete devices. Select a device by the parameters your require directly. Are you thinking of Vgsth for example ?


You can design in CMOS if you like although most discrete circuits I know of are typically mainly or all bipolar. Choose the technology that you

*need* for your application.


Reply to
Pooh Bear

I really think you ***need*** a copy of Win's pre-blog epic

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Reply to
martin griffith

Never been in a pasture in the winter, huh? ;-)

Cheers! Rich

Reply to
Rich Grise

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