I don't see any so special parts that would need an order from the US (e.g. digikey): the ADA4522 would also be available from Farnel/HBE or Arrow in Europe. The other parts are even more common.
@echo88:
The DC CMRR is essentially the same as an offset voltage that depends on the common mode voltage.
The diagram may be from a few samples tested in detail. These are sometimes slightly better than typical grade ones.
At the very high level the CMRR and PSRR values could also be limited by the measurement system.
I don't think this circuit would need the absolute highers performance amplifiers. The voltage is still relatively high (e.g. usually > 100 mV) and there are other sources of noise (especially the resistors) and drift (e.g. from leakage)
The circuit may not even need a 2 nd high supply voltage AZ OP, as the main buffer / amplifier behind the filter. The amplifier for the Zero adjust could use an amplifier with 5 V supply (this would help with an lower cost ADC like the µC internal or maybe an MCP3421). One may not even need an AZ OP here, if one has some MUX before the input to select the point to test and include a zero here. At least the zero check signal would be low impedance, so no need for a high impedance source.
Anyway the exact choice of OPs is not yet the important point - they can be changed even with a ready made board. It's only the question if something like a bootstrapped supply is needed. Given that the ADA4522 is not that expensive I would keep the circuit simple and use an OP with high supply range. This would be especially an advantage if the output would be with gain. I would consider an gain option worth to include.
The relatively high bias should not be a big problem for the buffer after the filter, as the impedance is constant and there would be an zero adjustment anyway. AFAIK the AZ OPs have quite some input current, but this current is rather constant.
So far the circuit I have in mind would start with 2x1N829A in series, so that the PWM DAC would give some -0.2 V to +11 or 12 V. The output amplifier (e.g. with ADA4522) would be switchable between gain 1 and about 2. The maximum output could be something like up to 24 V and maybe 100 mA, possibly also 1 A up to some 5 V. An extra, crude hardware voltage limit would probably be a good idea. The output would be the usual 4 wire output with extra sense inputs. To keep the circuit simple, the sense input may not be very high impedance though, especially the low side sense.
With an extra 4 wire resistor one could also use this as a current source, e.g. for current up to some 100 mA or 1 A and down to maybe some 100 µA, depending on the resistors used. Precision for the current may not be that high, especially for the higher currents, as the DAC would operate at the low end. If the resistors would be internal, I would stay with manual switching to keep the circuit simple - the switch would be not critical. The tricky part could be some protection (shunts are potentially rather expensive).
The supply would likely need some mains transformer. However the voltage needed are a little odd, like -9 V, + 5 V, +15 V ?, + 22 V and maybe +28 V.
So it one might either have quite some loss at linear regulators or would need more than 2 secondary voltages.
Unless high current is needed, the total power should still be moderate (like < 10 W).
So far this could provide voltages up to about 22 V and down to maybe 100 mV with reasonable fine settings.
I don't yet have a good (simple) idea on how to allow an test of the output gain stage. It could be done with a second amplifier made especially for adjustment. Instead of towards 0 V this would be against some 10 V. So it can be done, though not very elegant. The check/adjustment would be a fixed resistor divider against 10 V from the PWM-DAC in x1 mode and x 2 mode. This would also give a value to the 10 V resistive divider that might be used for an auxiliary output with possibly lower noise. The resistive divider does not need to be long term stable - so no super high grade resistors need, but likely still good ones.
At least for the beginning I would have the digital control via an isolated UART (likely with USB-uart bridge) to a PC. So that the display / keys would be a later step. The PC side would still need to do quite some controls / math.
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