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Edwin Armstrong’s Impact on Connected Medical Devices

My doctoral work was on the design of ultra-low power circuits and systems for medical devices.

If you’re suffering from insomnia and want to geek out on some math, here’s your chance:

During that time, I came across the work of Edwin Armstrong, who is an engineering hero of mine.

You’re probably wondering exactly who Edwin is but the funny thing is, he’s had a dramatically bigger impact in your life than you know.

Edwin Armstrong was a true genius of the 20th century. He invented wireless communications techniques and architectures that are used to this day – think frequency modulation (FM) and the superheterodyne receiver. He also invented a type of receiver called a “super-regenerative amplifier” (SRA), which is a lot less common these days.

I decided to design an SRA and went down the theoretical rabbit hole to develop a mathematical model that would explain its frequency response.

This was tricky because most systems are linear, time invariant and employ negative feedback. The SRA is nonlinear, time variant, and employs positive feedback, taking advantage of the huge amplification that happens when a system becomes unstable.

It’s fricking genius and one of the reasons I admire Armstrong so much.