8580 Opamps - libsidplayfp/SID_schematics GitHub Wiki
Unlike the 6581, the 8580 has real OpAmps, formed by a temperature compensated differential amplifier, an inverter and a non-inverting output amplifier:
In the differential amplifier sensing +in and -in, we have 4 FETs instead of two. That's a temperature compensation.
Layout for all the OpAmps in the 8580 looks pretty much similar, except that the OpAmp which generates the gate voltage for the frequency control DACs has a smaller feedback capacitor; in other words, it's supposed to be faster than the others.