Simplest analog transistor-level circuit to run my first sim

[Donna Olsen]

I'm trying to learn the basics and would just like to know where I can
find the simplest ANALOG circuit to run a spice simulation on.

I've already run on an RC circuit and on an inverter, but all the analog
circuits I find (for example, model files) are too complex.

What's the simplest circuit with CMOS transtors for a newbie who wants to
run a simulation that they can mentally understand?

(a picture of the topology would be great)

 

[Donna Olsen]

On Thu, 04 Oct 2012 18:27:53 +0000, Donna Olsen wrote:

What's the simplest circuit with CMOS transtors for a newbie who wants
to run a simulation that they can mentally understand?

It looks like a two-xtor current mirror, from page 613, Chapter 20 of
Baker (third edition) is the simplest analog circuit to implement that
has transistors and which wiggles interestingly.

It took a while, guessing at the xtor & resistor values, but I've at
least started a DC Analysis on that.

Thanks!

 

[J.G.]

On Thu, 04 Oct 2012 18:27:53 +0000, Donna Olsen wrote:

I'm trying to learn the basics and would just like to know where I can
find the simplest ANALOG circuit to run a spice simulation on.

Every analog designer has only four circuits in his toolbag.

1. Current mirror
2. Cascode
3. Differential pair
4. Common-mode feedback

Learn those, and you're an analog designer.
They're all very simple.

For example, a current mirror is merely two transistors of the same size
with the same bias voltage such that the drain currents are the same.

My advice:
Understand the 4 circuits above; simulate them; understand them; and
you'll be a bona-fide analog circuit designer.

 

[Bob Stevens]

On Tue, 16 Oct 2012 16:09:00 +0000, J.G. wrote:

Every analog designer has only four circuits in his toolbag.
1. Current mirror
2. Cascode
3. Differential pair
4. Common-mode feedback

Remember, everything they tell you in the text books is wrong!

For example, the texts will say the purpose of the cascode is to increase
the output impedance of the current mirror ... but they confuse things
just so they can write 1000-page CMOS Design textbooks!

Likewise, as a dozen so-called analog designers what the purpose of an op-
amp is, and they'll likely say it's something along the order of high
gain, but that too is only making something simple complex.

KISS is what analog design is all about.

BTW, the Cadence software is nothing but the opposite of KISS. There is
analog EDA software out there that is extremely simple - just google and
you'll find it.

 

[Bob Stevens]

On Tue, 16 Oct 2012 17:29:52 +0000, Bob Stevens wrote:

Every analog designer has only four circuits in his toolbag.
1. Current mirror

http://www.siue.edu/~gengel/ece584WebStuff/CurrentMirrors.pdf