Saket Vora

Missed circuits class for the 2nd time this week due to waking up late. Going to bed at 3 or 4am isn’t a good idea. I really like the circuits class too. Sigh. I need to watch the taped lecture.

The Big Game of Stanford vs Cal (Berkeley) approaches! It is on Wednesday at around 4pm. In the small circle at the center of the Intersection of Death, a GO STANFORD banner was erected. This paled into comparison to the BEAT CAL banner that went up on the back of Meyer Library, facing Escondido Road. This banner stood 3 to 4 stories tall and about 25-30 feet wide.

Posters were up everywhere advertising the annual Gaieties, a theater performance put on each year that pokes fun at and honors the Stanford-Cal rivalry. This year the theme is “Herbert Hoover and the Order of the Bearclaw”, a reference to the quarter-long controversy regarding the Hoover Institution, a conservative think-tank, separate from the university, but located in the heart of campus, invited Donald Rumsfeld to be a “Distinguished Visiting Fellow.” The faculty senate, along with nearly 4,000 students signed a petition against this move. Most of the faculty involved object to the title ‘Distinguished’, which implies a higher standing or honor. They see none of this in Donald Rumsfeld. In an interview, even the director of the Hoover Institution agreed that most foreign policy analysts, even the conservative ones, would agree that Rumsfeld’s tenure was not ‘distinguished’ at all.

The posters feature wonderful graphic design, right in the mood of Harry Potter. I would take a picture, but….well, you know. I’ll try to bring my webcam out with me tomorrow.  You can see some videos related to the Gaieties at this year’s website: http://www.orderofthebearclaw.com. Cal has a bonfire and pep rally in front of their Greek Theater.

Sapana sent me a link about The Play , and I started to read a bit about the longstanding rivalry between Stanford and Cal. It really occurred to me then about how much NC State lacks in traditions. The rivalry between Stanford-Cal goes all the way back to 1899. Some Stanford students got a lumberman’s Axe and chanted “Give’em the Axe!” and during an 1899 baseball game would cut blue and yellow ribbons at the game. Stanford lost this first ‘Big Game’, and two Cal students stole this Axe. Then in 1930, twenty one Stanford students performed a daring raid to take back the Axe. To do it justice, I’ll quote from the Wikipedia entry:

After the rally, four Stanford students posing as photographers temporarily blinded Norm Horner, the Grand Custodian of the Axe, with camera flashes. In the subsequent scuffle, the Stanford students grabbed the Axe while several others disguised as Cal students tossed a tear gas (or smoke, depending on account) bomb at the Cal students who guarded it. The Axe was taken to one of three cars which sped off in different directions. Several other Stanford students (disguised as Cal students) further delayed attempts to recover the Axe by organizing a search party away from the direction of the getaway cars. Although several of the raiders were caught, the Axe made it back to Stanford where it was paraded around the campus.

How amazing is that?  These students came to be known as the Immortal 21 at Stanford.

The Axe lay in bank vaults while the schools figured out what to do with it. Somewhere along the way it got its handle sawed off. Ultimately, it was decided that it would go each year to winner of the Big Game. So it is mounted on a plaque with all the scores from the Big Games throughout history. Though, for the famous 1982 game, whenever Stanford has the Axe the score is changed to 20-19, because that touchdown should never have counted. Cal changes it back.

I believe I’ve mentioned this before too, but in honor of the famous role the Stanford band played in the 1982 game, the ceremonial transfer of power from the band director to next year’s band director takes place with 4 seconds left in the Big Game, the time that the Band stormed the field.

Need I remind you that this year is the 25th anniversary of The Play? A lot of excitement here.

So I ask: how does NC State not have these kinds of rich traditions? UNC was founded in 1789. NC State came along in 1887. The two are closer in distance than Stanford and Berkeley. Both have large fan bases in town, with generations of families attending these two schools. Seems strange.

Reading about these things also makes me really admire the things that universities can stand for and represent in society. Perhaps its the bias talking…after all I’ve been in university for the past five years, but what an influence these places have! It’s a chance where young people can have an amazing time, a place to really start learning about the world, to have fun, to remember for a long time. And look at all the amazing universities across this country. So much history and tradition and reputations. And places that are public too! UNC, Virginia, Michigan, Texas, UC system, etc. Despite being a proud and dedicated member of the Wolfpack community, it’s very easy for me to admire the pride and reverence my friends and sisters have for UNC, or the people I’ve met from Berkeley. Such excellent schools! I feel America is unique in the role that public universities have in this country and the far-reaching influence they have. We cannot lose this.

It’s late, I better get to bed.

I actually went to my statistical signal processing class for the first time in a month today. I’ve lately just been watching the lectures online. And I was reminded at how little I understand of the material. Meanwhile, an Indian guy in the 4th row was telling the professor “I’m not convinced by your explanation that this is true.” Jeez.

I spent about two hours re-watching two lectures and looking over the sections in the course reader before spending two hours in the TA office hours. Helped a little bit. The TA spent 30 minutes trying to solve part b of question 5, and wasn’t getting anywhere. You can guess at how that bodes well for me.

Spent about 4 hours on this class’s homework tonight. Didn’t finish a single problem. I just tried to understand two problems, but I just don’t know whether I’m formulating these questions correctly or the mathematical way to finish their solutions. Every week this it feels like an exercise in futility.

Meanwhile, Vista is proving to be the absolute abysmal piece of crap it is. If a program happens to stop responding, Vista decides that the entire OS should lock up. No, you don’t get to open the Task Manager and try to shut the unresponsive program down. You need to hard restart your machine. Oh, all you wanted to do is open a web browser and play a mp3 at the same time? Too bad. And did you hear the news? The new service pack for Windows XP is supposed to make it performance twice as Vista. Even worse? I’m using Vista Ultimate. This is supposed to be the best version! What horrors are the other poor souls who have degraded version of Vista going through? Sigh. The highlight today was having some chevre cheese (goat’s cheese) with Triscuits this evening. That and a bowl of rice was my dinner.

In case you’re wondering, this is the ‘topology’ of the amplifier we’re building. Click on the image for a more readable view.

But this is just for looks. When it comes to entering this into our simulator, you have to define it all by hand. An example would be:

And so on.  Once you can start to visualize a circuit network though, its faster just entering it in by hand rather than drawing it.

So tomorrow school starts up again. Short day cause I woke up really late. It’s going to be a busy two weeks….the waiting before I get reamed on my final exams.

I watched the championship game of the Old Spice classic — NC State vs #19 Villanova. I’m not sure when I’ll get to see NC State play on ESPN2 again. It was a nailbiter. Being an NC State fan is a trial of faith. We gained the lead at the half, but Villanova kept chipping away at it. The last several minutes we were in a drought. Villanova goes up by 1 point with 2.2 seconds left. But then, on the inbound, Gavin Grant is fouled when going for the three! He misses the first, makes the next two for the go-ahead score. Villanova has 0.4 seconds, and despite the ball nearly going in, the Wolfpack came away with the win.

Later, I was watching most of the Eagles vs Patriots game. It was amazing — the Eagles were playing their best game in a while and was even leading going into the end of the 4th quarter. But then the QB gave up a bad interception on an unnecessary pass, and the Patriots scored to ultimately win it.

In other news, we have a much more optimized design for the 214 project! The last post showed a power dissipation of 47.27 mW. By implementing a real bias network and fine-tuning some values (trial and error Spice monkeying!) I was able to get:

The following specs were measured using our scripts.Description:                 Achieved

--------------------------------------------------

Settling Time (ns):     39.31

Static Error (%):     -0.010

Dynamic Range (dB):     90.10

Power (mW):             21.85

--------------------------------------------------

Congtratulations! Your design has met the spec  :) 

21.85 mW now! We are well within the 0.025% static error requirement. I can reduce the settling time (the spec is 40ns) but that will take more power. I am still very unhappy with a parameter known as the phase margin, which is measured in degrees. I was designing for a phase margin of 75 degrees. Many of the resulting parameters my design process calculated were matched in simulation. Yet, my phase margin is only 41 degrees. This is bad: not only do you want your phase margin to ensure stability for your amplifier, but a phase margin of 75 degrees also improves settling time. If I can somehow get my phase margin higher, I might be able to further reduce the power while meeting my specifications. This tells me that I am neglecting to factor in some rather important parameters into my design process. I need to read up on frequency response of two-stage telescopic OTAs.

Two random ways to finish this post. I’ve been lately listening to Bloc Party’s Silent Alarm, and here is a picture of my Vista’s sidebar….how I’m keeping track of people.

The timezone messed me up today — I thought the Notre Dame vs. Stanford game was 3:30 PST when it was actuallyEST. So I missed out going to the game. Nader came over and while I pecked away at the project, we watched the game on ESPN. What a terrible game. So many turnovers. So many bad penalties. Horrible officiating that is becoming the trademark of the Pac-10 — Notre Dame had a great touchdown pass that was ruled incomplete, even though the replay clearly showed the receiver had a hand under the ball when he hit the ground. Our starting QB, Tavita Pritchard, was once going into a slide when a ND defender led with his helmet and smashed into Pritchard’s helmet. Our QB’s head got torn off and it looked like he lost consciousness for a bit. No flag. The announcers were stunned. So Ostrander comes in, but then later injures his hand. While our third string QB was warming up, Pritchard comes back out. His helmet had been taken away from him earlier..and the announcers were saying “Coach Harbaugh, get him out of the game.” He was hit again, threw some weak passes. Horrible. Our kicker missed 5 field goals. We were on the goal-line at the end of the game, and our QB Ostrander threw two TD passes — except one was bobbled by the receiver and the other went right through the receivers hands. Sad.

After the game ended we got to working on the project. I wish I could have watched the Kansas vs Missouri match, but Mike kept me posted. It’s amazing that Kansas lost…another #2 goes down.

But anyway. After much explaining and teaching, Nader finally got  a bias circuit built for my amplifier topology and he was even able to improve the specs. So we currently have something we can turn in. It’s kinda ugly and not very creative, and takes around 34 mW of power, but it meets the specs. The new amplifier I built is also meeting the specifications too. So I think we’re doing alright.

I also tried a hefeweiss beer by Hopf. That brings the total number of hefeweizens  that I’ve tried to around 13. Weihenstephaner is still the best.

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
--------------------------------------------------
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.

Ok so I’m late a day. Hope you all had a nice time. I watched the NC State vs Rider basketball game in the morning. We were horrible the first half but ended up winning the game. Then got back to work on my 214 circuit project. My spirits started to sink — I started uncovering some systemic errors in my formulation and was getting frustrated with Excel. The program lacks a useful interpolation function, and I was getting confounded by problems that should not happen — certain functions requiring the input cells to be the same worksheet, for example. It’s silly — I’m working with 20 worksheets in my file. I ended up migrating my entire design flow over to MATLAB. I ended up skipping out on the Thanksgiving Day dinner being help by the Graduate Community Center and opted to have some leftover rice pilaf. I continued working straight through the evening and it started to pay off — I was getting results. All my transistors were in the right mode of operation. Jimmy and his partner called and I ended up talking him through part of the project over the phone for over an hour. I’m meeting 2 of the 4 requirements, but I’m having trouble increasing my amplifier’s gain. You see, increasing the gain of an amplifier reduces its static error. The reason is that my dynamic range is only 76 dB, when I need it to be 90 dB. So I have to both increase gain and reduce noise.

I celebrated by warming up some chili and canned corn. I tried some other strategies on improving my gain, but unfortunately nothing really worked. I think I’m going to have to reverse my design…basically swap my n-mos and p-mos transistors. So far I’ve put about 35+ hours into this project…better now than during the upcoming weeks.

Not planning on much at all for Black Friday. Don’t really need anything. Except maybe a webcam for home.

Despite getting only 4 hours of sleep, I woke up at 6am today and got ready. I met up with Lei (equally tired) and we took a drive around the bay. We drove 280 north to San Francisco, far more scenic than 101. As we drove up, we saw a dense river of fog hug the bottom of the valley, a rather startling sight for those unaccustomed to it. Crossing the bridge, we ended up getting lost among small neighborhoods and towns, ultimately driving north towards Mt. Tamalpais and Muir Woods. Our tiredness combined with the uneasy contract we have with Mornings made the twisty turns less than enjoyable. Still, the view from Mt. Tamalpais was spectacular, seeing the entire Bay and the San Francisco peninsula with its mass of skyscrapers. On our right was the expanse of the Pacific. Continuing our drive, we arrived at Muir Woods. I had visited here on the road trip, but Lei wanted to see a real forest and it is a nice hike. We took a 3 mile trail and looked at a redwood that fell on October 7th. Muir Woods feels ancient, yet change occurs daily.

After a snack we headed towards San Rafael and then the 580 bridge towards Berkeley. I noticed quite a number of Indian restaurants and stores while driving down their University Avenue towards campus. We parked outside and walked through the central and northern parts of campus. Most of Berkeley is at the foot of the hills, but some buildings and are definitely up on the mountain. The campus is much smaller than Stanford, in the shape of a trapezoid. Walking at a casual pace, we went from the west end to east end in 10-15 minutes. In total area, it’s about 40-50% smaller than NC State’s central campus. The buildings are not uniform, in either style (ie, Univ of Maryland) or materials (ie, NCSU). Many buildings feature (and forgive my lack of architectural terms) what I call ‘California style neo-classicism’. There are neo-classical elements I would not be surprised to see on buildings in Washington D.C., but with a spanish-style terra cotta tiled roof. Other buildings are very distinct, like the emerald green tilework of the CS building. The library is white marble lined with high ceilinged gorgeous reading rooms flooded with natural light. You know, some people say Berkeley’s campus can look pretty ghetto, but I didn’t see any areas like that. I did not visit the southern part though. The town of Berkeley is what you’d expect of a undergrad-heavy state college. The two main streets are full of restaurants (heavy leaning towards Asian and south Asian), cafes, and stores. It certainly has a more low-key aura than the tree-lined University Avenue by Stanford. All the university buses looked unnecessarily old, and Lei and I poked fun at the hippie implications all around us. A whole store dedicated to indoor agriculture lighting? Why would anyone, near Berkeley, want to grow plants inside? I did grab some coffee at a small coffee shop and later Lei and I grabbed a slice of pizza from a hole-in-the-wall pizza place. Both turned out to be good.

After Berkeley we headed home. The early start and lack of sleep took a heavier toll than we thought it would.

So where are the pictures you might ask? Sad news: my Canon S2 IS is dead. I bought this camera in July 2005, before going to Europe. The camera produced approximately 50 GB of content since then. I turned it on this morning with a fresh charge of batteries to find the screen black. The menu is shown but no images appear on the screen. I can view old pcitures without a problem, but I’m not getting any pictures from the sensor. I’ve looked at some forums and this has happened to others. I can pay Canon around $125 to fix it. I wish I could have lasted another year, but it did have a good run. Oh well.

Any suggestions for a replacement? Thanks.