2 ms·

Of course National Semiconductor had a chip for this, the LMC669 Auto-Zero. https://www.electronicsurplus.com/national-semiconductor-corp-lmc669cd-ic-auto-zero

• kragen 2y ago
  That's only rated good to 5 μV, according to the datasheet. You'd probably be better off with a non-auto-zero LM324B, whose worst-case Vos is rated at 3 μV IIRC. Of course it didn't exist at the time (01989) which is why National made the LMC669. But the potential advantage that building a chopper (or auto-zero) out of ordinary opamps would be that you don't need to source, order, and await specialized chips. A long-discontinued bolt-on auto-zero for a regular opamp has almost all the disadvantages of just buying an auto-zero opamp.