This page is a grab bag of how-tos, notes, project reports, rules of thumb, and other useful information I wish I had earlier in my career. It's definitely a work in progress as I go through my notes to decide what to share, and add context to help the information make sense. My goal is to write content that's not as prevalent on the internet. For instance, I may not talk about basic OpAmp circuits, but aspects of OpAmp noise analysis and low-noise OpAmp circuit design. As such, these musings are geared toward a technical audience with a background understanding of the material.
A technique to estimate how much bypass to add to help meet signal integrity and EMC requirements!
A reasonable approximation of the maximum frequency of a square wave can be found by measuring the 10-90% rise time.
A rule of thumb for estimating wavelength to distance in a PCB and the distance associated with group delay.
General estimates of the relative costs associated with choices in PCB design.
When to apply the Rules of Thumb.
Resistive Thermal Noise
Power spectral density of resistive thermal noise. (Coming soon!)
Types of noise, noise sources, calculating noise, and noise simulation.
Designing OpAmp circuits for SAR ADCs
Picking OA's, necessary GBW and RC values, time constants, OA noise vs. ADC noise vs. thermal noise, phase margin, and other considerations. (Coming soon!)
Signal propagation in FR4 material is about 6”/ns.
The wavelength of a 1GHz signal in a PCB is approximately 6”.
Estimating the bandwidth of a square wave signal from its rise time.
"So, you're telling me the product ...in the metal box... is failing FCC Class ...A?"
Plus, a means of estimating how much bypass to add.
Choose PCB dimensions to minimize how much stock is wasted.
How layers, materials, copper weight, hole size and density, and soldermask color affect PCB cost.
Adjacent Trace Coupling
Ways your choice of trace spacing and guard rings can kill your noise budget. (Coming soon!)
Power Supply Line/Load Regulation and Ripple
Does your supply meet the needs of your design? (Coming soon!)
Power Supply Output Impedance vs. Frequency
How fast can the power supply respond? (Coming soon!)
The Product Development Stages
EVT, DVT, PVT, MP (Coming soon!)
That week I was going stir crazy and decided to measure how many joules the electronics I take backpacking require to fully charge and how many joules my USB battery packs could provide to find which battery pack was best to bring, minimizing the weight carried and optimizing the energy-per-ounce factor.