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@@ -6,3 +6,6 @@ so basically i live in ann arbor now
 - [Fall 2023 Wrapup](f23_wrapup.md)
 - [Fall 2023 winter break wrapup](f23_winter_break.md)
 - [Winter 2024 Wrapup](w24_wrapup.md)
+    - [EECS 482, Intro to OS](w24_482.md)
+    - [EECS 373, Intro to Embedded System Design](w24_373.md)
+    - [EECS 311, Analog Circuits](w24_311.md)
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+# Winter 2024 Course Review: EECS 311
+
+2024-05-03
+
+Course Title: Analog Circuits
+
+Rating: 3/5
+
+## Instructor (David Garmire)
+
+On the first lecture I had a feeling I've seen him before. I checked the
+"courses offered" spreadsheet at SJTU last semester, and he taught 281.
+
+He's all nice and stuff, and he never judges you. But the vibes are not
+the best I could imagine. He's pretty reserved, and often seems in doubt
+of himself, as if he's teaching it for the first time. Contrary to two
+other EECS professors I had this semester, he had the least "authority
+figure" vibes. (Robert Dick sometimes has too much; Brian Noble has it
+just right.) Sometimes we can't tell if we're wrong or he's wrong. If we
+point out he _might_ be wrong, he stops right away, which is good, but his
+first assumption is always he _is_ wrong, which hurts credibility if he's
+not.
+
+One thing I like about David Garmire is his analogies. The best one is how
+the NPN BJT is like a leaky tub of water.
+
+## Course topics
+
+- Introduction & review (e.g. Laplace transform, Bode plots)
+- Opamps
+    - Inverting & non-inverting amplifiers
+    - Nonidealities
+- Sallen & Key filters
+- Diodes
+- BJTs
+    - CE, CC and CB configurations
+    - High frequency
+    - Degeneration
+- MOSFETs
+    - CS, CG and CD configurations
+    - High frequency
+    - Degeneration
+
+### Personal reflections
+
+Compared to EE majors in the room, I was all chill about this course.
+I enrolled because I was interested, not because I was required to. It's
+not like my degree or life depended on it. But my life does depend on
+music, and it's part analog circuitry.
+
+Personally, I think Sallen & Key (S&K) just came out of nowhere. There was
+no motivation. It's just a table of equations that we use to solve for
+like six unknowns. It's not fun.
+
+BJTs are the most complex topic. You've got three currents coming in or
+out of the BJT, one of which can _sometimes_ be ignored. You have three
+modes: cutoff, active and saturation. To make a useful amplifier, you have
+to juggle the voltage correctly to bias it in the right range; then you
+get a transconductance, then you convert it to a linear circuit with
+a dependent current source, then you either do a bunch of nodal analysis
+or just apply formulas. In most cases formulas Just Work™.
+
+I remember taking 215 (the OG circuits course) and scoffing at the notion
+of a "voltage-dependent current source". Like who would use that in real
+life? I bet you ten bucks you can't even build one. However, it turns out
+if you apply superposition principle to a non-linear circuit, and
+constrain your input to a narrow range to pretend it was linear, an
+"X-dependent Y source" appears, and it helps you apply linear formulas to
+an otherwise unholy "e to the power of v over something" pasta.
+
+MOSFETs are just BJTs but with different names for everything (the "active
+region" of the BJT is analogous to "saturation mode" of MOSFETs). Also one
+of the three currents is gone (except in high frequency) and you juggle
+the voltages in a different way.
+
+Overall, this course was more inspiring and extensive than I thought.
+However, it was also pretty elementary. I enrolled because two of my
+hobbies (ham radio and music) are closely relevant to analog circuits, and
+I had hoped to build an amp after this course. Although half of the course
+_is_ building amps, it's pretty theoretical.
+
+### Building amps
+
+The majority of our discussion toward the second half of the course was
+transistor-based amplifiers. Interest was mostly on NPN common-emitter or
+NFET common-source, but there are other configurations to fit niches. We
+had these parameters to optimize for:
+
+- Gain (open-circuit, loaded, or overall)
+- Output voltage swing (how many Vpp can you output before clipping)
+- Bandwidth (low & high 3dB cutoff)
+- Output impedance (affects loaded gain)
+- Input impedance (affects overall gain)
+- Power dissipation (how much DC power does it draw)
+
+Desiging amps, especially multi-stage ones such as what I did in lab 5, is
+an ardous chain of trial and error. My observations are
+
+- Build first stage with around 10x the signal impedance
+- Think about gain first
+- 1 mA is usually a good DC current to start with
+- If it doesn't work, try 1.5 or 2
+- DC current determines gain, output impedance, and power
+- Too little and too much current both lead to bad overall gain
+- Decouple all stages by chucking in a 1 µF to 47 µF cap
+- If load impedance is small, add a buffer at the last stage
+- Bandwidth is the last thing to worry about
+- If you need to squash highs, add a cap from a signal to ground
+- If you need more lows to pass, use larger decoupling caps
+
+Those tradeoffs are an inevitable part of an electronic engineer's life.
+Besides, some transistor parameters (such as beta) depend on temperature
+and fab variations, so we had to add feedback to make our circuit less
+susceptable. I now appreciate the amount of work that analog engineers go
+through just to create a usable amp.
+
+### Sine wave breakdown & shoutout to Samuel
+
+Another way to look at amp-building in the scope of 311 is to break down
+a sine wave:
+
+x(t) = A * sin(ωt + ɸ) + b
+
+- A: amplitude, or in our case, gain. We talk _a lot_ about gain. Arguably
+  the _point_ of amps is gain.
+- ω: frequency. We spent two lectures on high frequency response, one for
+  BJTs and one for MOSFETs, which discuss internal capacitances within the
+  transistors. The effect of external capacitors is discussed in the first
+  half of the course, in analog filters.
+- ɸ: phase. We hardly ever talked about phase, and phase Bode plots were
+  not required. However we were required to tell apart inverting and
+  non-inverting amps.
+- b: DC offset. In general not a thing to worry too much about. If you
+  need to get rid of it, just add a cap. If you need it back, bias your
+  base/gate/whatever. It's just a stepping stone for the AC signal.
+
+The frequency discussion is very interesting. We used a duo of methods
+called OCTC and SCTC (open/short circuit time constant) to estimate the
+lower and upper 3dB cutoff frequencies. They work like magic. Two separate
+occasions, the estimate I got with them is within 1% of SPICE simulations.
+Huge kudos to Samuel Nolan, our IA, for explaining the methods in the lab.
+He is the GOAT IA this semester.
+
+### Analog vs. digital
+
+On the first 311 lecture, David Garmire talked about the quote unquote
+"superiority" of analog circuits over digital ones, such as energy
+efficiency. Somewhat ironically, exams two and three had one design
+problem on each, and the premises are both to design an amplifier for an
+ADC, presumably into a chain of DSP algorithms.
+
+Many systems now use DSP, which often is cheaper and/or more noise-proof,
+so unless you're an retro-audiophile or still live in the 1900's, very few
+things actually have analog circuitry from top to bottom. They usually
+have at least one piece of integrated circuit somewhere. But even if it is
+the case — he argues — analog circuits are essential.
+
+There was a 373 lecture dedicated to ADC/DAC, and later there were a few
+slides that discuss analog filters. It was one of the few occasions this
+semester that 311 was useful for another course. I am more than sure it'll
+be useful for 473 next semester as well.
+
+Robert Dick acknowledges that sometimes there are problems 1's and 0's
+cannot solve. One such example is high frequency noises in the ADC input,
+which cause aliasing, and are a pain to distinguish from actual signal in
+software. So the solution is to add a lowpass filter to the input.
+
+I am unsure whether my preference is analog or digital. On one hand,
+analog is cool because my bass is an analog system. But the DAW is digital
+(it literally stands for digital audio workstation). Let's leave it this
+way.
+
+## Labs
+
+Labs are the heaviest workload of 311. There are five labs in total, each
+spanning over two or three weeks.
+
+- Lab 1A/B: opamps
+- Lab 2A/B: S&K filters with opamps
+- Lab 3A/B: voltage boosting & power harvesting with diodes
+- Lab 4A/B: single-stage BJT amp, measuring beta and capacitances of BJT
+- Lab 5: designing a 3-stage amp
+
+The typical roadmap of a lab:
+
+- Prelab: Do calculations, simulate in SPICE
+- In-lab: Build circuit, measure with ADALM and Scopy
+
+Note:
+
+- The ADALM is a virtual lab kit USB device by Analog Devices
+- Scopy is the software to interface with the ADALM. It's got an
+  oscilloscope, a voltage supply, a multimeter, and a network analyzer
+  (which you use to get Bode plots). Thankfully it is open source and runs
+  on Linux (was a pain to install though because it's not in any pacman
+  repo or AUR. Had to manually build it because I didn't want flatpak.
+  Somehow it wanted a patched version of Qt and many other deps so I had
+  to build like six libraries and manually change CMakeLists so one of
+  them compiles)
+- SPICE is a circuit simulator. The lab docs mention LTSpice, which does
+  not run on Linux, so I used ngspice integrated in KiCad. Halfway through
+  the semester, KiCad upgraded to 8.0 which includes a major overhaul of
+  the ngspice frontend — huge improvement.
+
+In lab 3B, I built a circuit that harvests power from a 3.5mm jack to
+light up an LED. Naturally, I made it play Bad Apple:
+
+![Bad Apple playing next to an oscilloscope waveform. An LED lights up on
+a breadboard circuit](img/w24_wrapup/311_bad_apple.jpg)
+
+In lab 4B, I hooked an NPN BJT to a giant beast of a machine, the HP 4155B
+semiconductor parameter analyzer that thought it was 1997.
+
+![An HP 4155B semiconductor parameters analyzer displaying a graph. The
+date is "97AUG07 11:46PM"](img/w24_wrapup/311_hp_4155b.jpg)
+
+Despite not having an A/B, lab 5 took three weeks. After designing and
+simulating (but not building) a circuit, I needed to write a report for
+the design of my three-stage amp. It "must be written with a word
+processor", but did not mention which one.
+
+![Three pages of my report written with LaTeX, featuring a circuit
+schematic, a bode plot, a transient plot, and
+a table](img/w24_wrapup/311_latex.png)
+
+I used up like 10 pages of scratch paper (single sided) just for the
+calculations. Glad I did meet the specs.
+
+## Verdict
+
+It's just a gateway drug to EE. Don't expect too much — you won't be an
+expert when you walk out, but do expect mind-bending moments, like how
+I discovered that I've been misunderstanding BJTs for like five years.
+
+If your job involves interfacing with "weird" analog signals, like signal
+impedances in the megaohms, then this course is essential.
+
+Would be better if the lab was larger though. It's like a can of sardines.
diff --git a/docs/umich/w24_wrapup.md b/docs/umich/w24_wrapup.md
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@@ -14,6 +14,7 @@ them up into individual articles, listed below.
 
 - [EECS 482, Intro to OS](w24_482.md)
 - [EECS 373, Intro to Embedded System Design](w24_373.md)
+- [EECS 311, Analog Circuits](w24_311.md)
 - Other courses WIP
 
 ## Notable material gains