Tuesday, December 29, 2009

Retired Life

I have read some good trading books.

There is the classic "Technical Analysis of Stock Trends" by Edwards, Magee,
and Bassetti.
Another is "Trade Your Way to Financial Freedom" by Van K Tharp.

I have a long reading list that I am still working my way through.

(from an older, wiser friend)

Sunday, December 27, 2009

Articulation - The Power of Communication

Why are social skills so important (coming from someone who wished he had started training much earlier :) ). Here's one angle to consider : The better you are with people, the easier you open up and talk about what's important to you. Smart people discuss ideas. Ideas are your real children. Have you thought about why you have ideas that you never talk about? Because you're afraid of having them mocked at. You want to protect your children. But, with good social skills, you can create a safe place for your ideas in minutes. I was surprised today to hear myself articulate how what I really want to be doing is building security systems and applications - how I want to be in surveillance and remote monitoring. That is the key to this country going green and cutting costs in healthcare and achieving energy independence. We can do it if we approach it the right way. We are spending way too much money having people watch our backs when they could be doing more useful work.

Thursday, December 17, 2009

How Fast is a Wilson Current Mirror?

Assuming you want a reasonable phase margin (meaning, if you have two poles, keep the 2nd one at 2x UGB).

You'll see why your PMOS mirror usually gets away without any explicit compensation cap..

If we assume,

Then, assuming the source follower works good (i.e., its Cgs doesn't come into play because its V(S) = V(S) due to unity gain.. (nice, in reality, you don't get that because of the gmbs - so, straightaway, some of the CGS *has* to come into play)

Also, assuming that 
We get, if you go around the loop,
and 

So, if one substitutes the expression for gm, one gets, again, using 
What we are interested in is, how fast will the cap that the input current sees take to charge to the final voltage. Or, how does this Cc (which is what the I_in now sees) compare with the effective input cap for a simple current mirror? If you call that cap C_simple, it has to be 2 * W1 * L1 *Cox

Giving

Moral? If you want to see a benefit, keep the mirror devices' aspect ratio as low as possible and the aspect ratio of the cascode (which does the unity gain buffer role) devices as large as possible.