As the Raspberry Pi team has so gracefully publicized the Raspberry Pi 4 schematics (minus the SoC side for some reason), we can take a look at what kind of circuit they have implemented for the ...

The audio circuitry from the first Raspberry Pi. The schematic above shows the audio circuitry from the first Raspberry Pi. On the left are inputs from a pair of BCM2385 PWM lines, and on the ...