Saturday, December 12, 2009

Fall Quarter

Unfortunately, this is one of those blog posts where nobody knows what I'm talking about, so feel free to not waste your time trying to read it.

Anyway, I took three engineering classes for Fall 2009 Quarter; EE 341 - Discrete Time Linear Systems, EE 473 - Analog Integrated Circuit Design, and EE 476 - Digital Integrated Circuit Design. In EE 341 - Discrete Time Linear Systems, you pretty much cover many of the principles needed for most audio, image, and video processing. The course pretty focuses on applications of Z-transforms (which are Laplace Transforms for discrete signals), Discrete Fourier Transforms, Discrete Time Fourier Transforms, and Discrete Time Fourier Series.

In EE 473 - Analog Integrated Circuit Design, you essentially learn how to create amplifiers using 23o nm CMOS technology. For our final project, we developed an 80-dB fully-differential amplifier with several design specifications for input and output capacitance, phase margin, power consumption, output swing, and unity-gain frequency. We used a folded-cascode topology with a common-source second stage, biased with low-voltage cascode current mirrors. The circuit also implemented common-mode feedback, which we just included as a couple resistors and an ideal op-amp, and also Miller compensation. Unfortunately, we only had one week to do the project, and we ran into a pretty time-consuming problem, but eventually we got something that met most of the specifications after a rather frustrating overnighter. We could have done better if we had a little more time.



In EE 476 - Digital Integrated Circuit Design, we worked on a 45 nm CMOS process. Our final project was to design an arbiter circuit in behavioral Verilog, then using software tools to convert the Verilog code into logic gates. We drew out a series of 9 logiItalicc gate standard cells, with which we actually drew out all the transistors and connecting metal layers, and used an automated process to convert the logic gates into a layout using standard cells. Below is our resulting integrated circuit, which measures only 15 x 15 μmFont size², consists of 91 standard cells, for a total 362 transistors.



Here is our design for just one of the standard cells, the D-Flip Flop, which measures 1.235 x 3.23 μm². A Flip-Flop is essentially a memory storage cell, which holds one bit of information.


D Flip-Flop Schematic

Layout of the D Flip-Flop

It would take a long time to explain what's going on here. All the blue rectangles are the lowest metal layer, the pink rectangles are the second metal layer, all the red rectangles are polysilicon (used for the gates for transistors), the W's indicate the p- or n-doped wells, the triangles indicate p- or n- heavily doped regions. The layout image directly translates to the schematic above. Each of the colors represents a different mask during the manufacturing process. Since it costs well over a million dollars to manufacture an integrated circuit, we mostly relied on simulation software to test our design.

Most of the work in this quarter was learning how to use the Virtuoso design suite to design and simulate our circuits. Unfortunately, the University of Washington file servers were running extremely slow, and so we wasted a lot of time waiting for the mouse to catch up. It was also frustrating, since there were three classes all trying to use the University of Washington's only 20 Linux computers at the same time.

Saturday, December 5, 2009

Roland C-330 Home Organ

I need to introduce you to the newest member of my family, the Roland C-330 Home Organ. I'm officially the first one in Seattle to actually own one. My Dad and I went down to pick it up from the Rodgers factory in Hillsboro, Oregon over Thanksgiving weekend, and we were quite confident that it would fit in the Toyota RAV, since the Rodgers salesperson we met with earlier mentioned that it was small enough to fit in a car. As we figured out, JUST BARELY. We had to remove all the packaging. After getting it back to my apartment, I set it up and started to crank it up to see how loud it would go. Less than 30 minutes into playing it for the first time, somebody knocked on the door and complained I was being too loud... Oh, well, I guess that's why I got head phones!




Below, I made a few recordings in my free time, to illustrate some of the sounds of this magnificent instrument. I will post more as I make them. The recordings came out perfect quality, and may have created some background noise and lost a little bit of high-frequency information as I converted them to MP3 format, so they sound a little different. They're not perfect, but they should at least give you an idea why I fell in love with this instrument. I recorded using the Line-in audio port on my Powerbook G4 using SoundStudio3.

O Lamm Gottes, unschuldig (O Innocent Lamb of God), J. S. Bach BWV 1095 - Uses mostly flute stops


Prelude and Fugue in G Major, J. S. Bach BWV 557 - Set with a high amount of reverb, to mimic a cathedral sound


Nun komm, der Heiden Heiland (Come Now, Savior of the Heathen), J. S. Bach BWV 599


Herr Christ, der einge Gottes-Sohn (Lord Christ, the only Son of God), J. S. Bach BWV 601 - Illustrates full organ sound