DAC1220 REF Schemtaic +-10V

[derZockerMP]

Hello, I want to design a schematic to output a 20-bit voltage ranging from +10V to -10V for a voltage source. The output of this circuit will be used for an output stage that amplifies the voltage to ±100V in four different ranges. What do you think about this rough schematic? Is there a way to simplify the circuit (by removing U8B) to achieve the ±10V output?

Best Regards

[Kleinstein]

The reference and the DAC output are on theory low impedance. In principle one may get away with a simple 1 OP-amp difference amplifier between the output and ref. voltage. However loading the reference will add some nonlinear error. It is also not clear how well the output handles loading: this can also add errors. Loading could be reduced by 2 additional, but less critcal amplifiers to provide most of the current (kind of virtual class A). So one would get more parts, but fewer critical parts.

[laichh]

May take a look in the DAS11001B datasheet, section 8.2.1 Source Measure Unit (SMU).

[derZockerMP]

Ok thanks, I will try it out on a prototype Board. Should I use guard traces around some nodes? Normally not because they are all Low Impedance Right?

[Kleinstein]

The 2 capacitor pins at the ADC chips are maked to want a guard (e.g. ground or ref.). At least it would not really hurt.