In #186465 you said some of that.

You haven't said whether you need to know any phase/frequency information about the sinusoid you're measuring.

Why did you decide not to "precision-rectify" the attenuated sinusoid and measure only the rectified waveform. That would eliminate any of the phase/frequency factors. Since rectification has "issues" as you mention, it would be useful to know how these affect your work, and how they're affected by the attenuation, i.e. how (or whether) the information produced by precision-rectification affects you.

You haven't said what your sample rate is, nor what the available bandwidth of your MCU is. Doesn't that have effect on your measurement? If you want only the peak, average, or RMS values, aren't those all calculable from just one of them? What's the nature of your AC signal? Is it a fixed frequency? Does it matter? If you're measuring the waveform to dermine Irms, isn't all the information you need embedded in that process? That nonlinearity issue is predictable, isn't it? How large an effect does that have on the attenuated values you measure with your ADC? What effect does noise have on your system? How precisely do you have to measure the voltage and current?

RE