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New for July 2017! On this page we have moved information from our SSPA page, and added a discussion of resistor dissipation.
Designing for graceful degradation is a worthy idea. It starts with deciding what failure modes a system must survive, then doing a little power analysis, and finally, speciying which components can literally take the heat. If done correctly, a power amplifier simply loses a fraction of its power when one of the constituent amplifiers fails; if done incorrectly, hardware fails spectacularly, starts a fire, and all hell breaks lose. Graceful degradation is not something that only applies to microwave electronics design. What about Hotpoint making refrigerators with plastic, such that a small compressor fire turns into a towering inferno, like the Grenfell tower in the news in June 2017?
This comment from Richard, concerning the Hotpoint refrigerator fire:
...the Hotpoint fridge fire in Grenfell was actually extinguished. It was only when the firefighters were leaving the building did they notice that the fire had somehow spread to the outside and some very combustible cladding which could not take the heat. I'm not saying it wasn't Hotpoint, just that this example is more complex than a fridge fire.
http://www.telegraph.co.uk/news/2017/06/20/grenfell-tower-firefighters-put-fridge-blaze-just-leaving-flats/
Graceful degradation is also a characteristic of AESAs and PESAs, topics for another day.
Here's a new page on how to specify size the power dissipation of resistors in SSPAs.
Check back soon for more information!