[sdiy] Low voltage synthesis?

Mike Bryant mbryant at futurehorizons.com
Fri Jan 14 21:58:44 CET 2022


Ø  But Class D amps are analog, right? :-)


Mine aren’t !  STM32F730 MCU driving an IRF2003 driving pairs of paralleled n type power MOSFETs (I use F20N60s).  Voltages might vary but most definitely ON or OFF :-)
A small calibration signal is taken back to the STM32’s A-D to model the output stage behaviour, but this isn’t used in real time, i.e. no negative feedback.


From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Mattias Rickardsson
Sent: 14 January 2022 20:35
To: Synth DIY
Subject: Re: [sdiy] Low voltage synthesis?

cheater cheater via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> skrev:
 I wonder what's being used in places like
mobile phones or wireless earbuds for example, they can't be running
+/-5V op amps or LV op amps with major crossover distortion.

I've used some mobile codec from Dialog to pump up the jam in a low-voltage application with mainly positive supplies, check out their stuff for some typical insight.

Mike Bryant <mbryant at futurehorizons.com<mailto:mbryant at futurehorizons.com>> skrev:
Nowadays mobile phone amplifiers are all digital - the digital audio (I2S possibly) digital signal is converted to a PDM signal which drives a class D amplifier and a simple LC reconstruction filter on the output.
Some years ago they did use DACs (e.g. Wolfson devices) followed by a Class D amp, until someone realised going digital -> analogue -> digital -> analogue was a nonsense.

But Class D amps are analog, right? :-)

/mr

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