Some discrete design questions

[Boki]

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.

 

[Winfield Hill]

Boki wrote...

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 ?

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

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?

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

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?

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

 

[Joerg]

Hello Win,

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

Some do:
http://www.allbusiness.com/periodicals/article/870655-1.html

Regards, Joerg

 

[Jim Thompson]

Hello Win,


Some do:
http://www.allbusiness.com/periodicals/article/870655-1.html

Regards, Joerg

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

...Jim Thompson

 

[Pooh Bear]

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 ?

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 ?

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?
Yes.


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?

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.

Graham

 

[martin griffith]

Hi All,

I am not familar with discrete design.

Best regards,
Boki.

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

http://www.artofelectronics.com/


martin

 

[Rich Grise]

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

...Jim Thompson

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

Cheers!
Rich