Saket Vora

I hung out and had lunch today with Matt Callahan, a friend from high school. He is like Stephen Marks in his expressive enthusiasm — a great guy. He went to Chapel Hill and got his degree in math. An active member in Nourish International, he was the lead organizer for the most impressive charity poker event I’ve ever known (when you’ve got a pro poker player donating hundreds of his DVD, $20 worth of goodies, and prizes like flat panel TVs…all donated…you know you’re doing something right). He is currently teaching sixth grade math at a recently opened school in East Oakland for Teach for America. We talked a lot about that, his experiences and such. It’s really remarkable. He has some incredibly smart students — kids who can score a perfect score on the math portion on the California state exam. But it’s tough because the overall environment makes it hard for these kids to focus. Matt was telling me that you put any one of these kids in a place like Palo Alto High School or Davis Drive and these kids could go to Stanford. Another thing that he said students like us never had to deal with — how to learn. What a learning environment looks like. The idea that you might not understand something the first time, but if you work at it, you can learn it. The fact that you can learn. Some interesting challenges — the students can handle adding and subtracting positive and negative numbers, but only if they are below +-20. If you get big numbers, its hard. The average at-grade level proficiency in sixth grade math for Palo Alto school district is 85% — the local middle school near Stanford has 95%. Oakland’s average is 20%.  Matt’s school? 9%. How do you design a lesson plan to teach a sixth-grade math concept when your class features grade-level proficiency from 2nd grade to 7th grade (most below 5th grade)? I salute people like Matt…wow. He said that one of the tough adjustments he had to make was that for nearly all of our lives, the main focus for students like us was learning. Everything else did was extracurricular. Oh, I signed up for IM basketball but its ok if I suck at it. Ok, so I miss a few meetings of that social activism club. But you always make sure you do well in school, and our group of friends in high school and college were like that. Now, he and fellow TFA first years are finding that they are working 70 hours a week at teaching, and they aren’t good at it. It’s a big adjustment.

In other news, I have an op-amp that meets the specifications.

13:11:35, Fri Nov 23 2007

The following specs were measured using our scripts.

Description:                 Achieved
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Settling Time (ns):     39.60
Static Error (%):      -0.01
Dynamic Range (dB):     90.01
Power (mW):             47.27
--------------------------------------------------

Congtratulations! Your design has met the spec  :) 

BUT. This is using an idealized bias network — need to implement a real one. Instead of 3 idealized current sources, I’m allowed only 1. So a bunch of current mirroring to do. This also uses two ideal voltage sources — need to get rid of those and use transistors. It also is too close to the margins — I need to make it more robust. But still.

So what is this project about? It’s just an amplifier. You send a tiny voltage into it, and it will make it into a bigger one. What are some issues? Well, to help minimize any noise that might get into your signal (which corrupts it), we use something called differential signals. This has the benefit of increasing the dynamic range too, which is a measure of the difference between lowest and highest signal you can handle. Speed is a big issue. How fast does it to take for your device to do what you want? Not only that, but what is the highest frequency signal your amplifier can accept? Human hearing lies between 20 Hz and 20,000 Hz. If the amplifier in your iPod can’t handle signals that are higher than 14,000 Hz, then you’re losing a lot.

Now, in particular, this amplifier is intended to be used in a circuit implementation called switched capacitor. It’s a way of bridging the analog world and the digital world. I haven’t done a lot of work with it, but I might later.

Anyway, tried picking up a webcam at Circuit City but they botched the pickup order. Held the wrong model and then sold out of my model. I’m gonna get back to work. Enjoying the Boise State vs Hawaii game now. Nuts how LSU lost, huh. What an awesome year for college football.