Actinica » teaching

Low noise, low drift techniques

Michael Beach — Fri, 12 Feb 2010 18:33:01 +0000

This presentation has a set of clear, well thought out images describing how chopper techniques can reduce 1/f noise, reduce drift, and even how to cancel the nasty charge injection of FET switches. It shows how modulation can reduce noise in a sensor amplifier system.

link to pdf of Kofi Makinwa\’s presentation, Dynamic Offset Cancellation Techniques

I first learned of Kofi Makinwa’s excellent work through the recent IEEE Solid State Circuits magazine, Winter 2010, Vol. 2, No. 1. He demonstrates a clever accelerometer that uses a small air volume as the ‘proof mass’. The Wheatstone bridge has been around a long time, but it’s clear it can be taught some new tricks. This is the first I’ve heard of a ‘nested chopper’ architecture. Great stuff. Check out Makinwa’s other publications at the IEEE.

I’ve spent some time trying to squeeze good data from MEMS sensors, and I know how difficult it can be. These articles show why adding some switches and circuit complexity can really pay off. And it’s only CMOS and FETs, so we get ‘em for free from Moore’s law, right?

SPIE Photonics West 2010

Michael Beach — Tue, 13 Oct 2009 19:45:58 +0000

We’ll be teaching a ‘short course’ at the Photonics West 2010 show this January.

Titled ‘Fluorescent Detection: System Design and Tradeoffs’, it’s based on work we did to help develop a hand-held chemical detection instrument for Cogniscent Inc., (homepage for Cogniscent Inc.) who have granted us permission to show off some of the things that went into that product’s design.

We also discuss various design options that were not selected for the Cogniscent system, and what motivated those decisions.

Here’s where you can find more information, at the SPIE website:

link to course description at SPIE website

Actinica Book List

Michael Beach — Sat, 31 May 2008 18:00:27 +0000

Ok, we have a book problem.

Both of us waay like good engineering books. A good explanation, or a great

graph that sums up why that camera ‘sees’ differently than my eyes, etc.

Since we’re always stumbling on more good books, this list will grow.

Drop by later see what’s new.

Here’s some of the books we like, as a pdf file here,

book-list_jan2008_san-serif

and here’s some more books we like:

the Feynman Lectures on Physics, a 3 volume set. Here’s a guy who can explain anything well. Like how sine, cosine and the magic number e all relate to the imaginary number i (square root of -1). He also has a great description of how a ’50 Ohm’ transmission line acts like ’50 Ohms’ no matter how long it is. For a really great puzzle – read his description of how charging a capacitor really involves magnetic fields outside the cap’s plates.