Knew about the better references (LTZ1000) in the 34470, and with the DMM7510 (they evidently use a special Fluke LT reference). Agree the LM399 should be "good enough", especially the pre-aged versions used in the 34465, not sure what is used in the DMM6500.
We've been "looking" at the higher resolution scopes for some time now, and already contacted LeCroy and others last year. Also watched with keen interest the new Siglent SDS6000 scope and will be evaluating it soon, although it's the 8 bit ADC version and likely not good enough
The PicoScope also looks attractive, but prefer an full fledged instrument rather than one that requires a laptop.
Even looking into using a "known good reference" to generate some of the Arbitrary Waveforms and make measurements with the DMMs and "infer" results based upon mathematically computed results. The HP App note based upon Swerleins Algorithm that alm referred has a note on how NIST used a precise and stable 8 bit DAC to create accurate sinusoids with remarkable precision, so our thought was to use this method for some Arbitrary Waveforms. We have even considering for some time making a special custom calibrated source for these waveforms. Even looking into a precision AWG (like the upcoming SDG6000) for such but all this effort will be after the upcoming demos next month.
If the project moves on to the custom IC design/fabrication phase then we'll need a means to evaluate the test chip performance, and preparing for this.
So yes we've been looking into this for some time now.
Best,
Creating precise AWG waveforms is not impossible. Amplifying and scaling them to 160V p-p with good pulse response and good DC accuracy is the fancy part. Especially into capacitive load, and if you need to do that fast..
Like Tautech says, new Siglent AWG is SDS7000A. Up to 1 GHz for sinewaves, 14 bit res, 24Vp-p output wit +-12V (24V total) offset range for total of +-24V output range, differential outputs, digital pattern generation and all kinds of goodies...
That will be interesting one..
Agree, the HV scaling with good DC performance as well as capacitive loads and such is difficult indeed, which we've conquered
Had thought the new SDG7000 series was going to be 16 bit DACs, but as you mention only 14 bit resolution. It's also going to be priced in the Keysight range, so likely well out of our projected budget.
So now the SDG6000X series is looking as a possible candidate. Can these be expanded to higher speeds with firmware like the SDG2000X series, where the hardware is all the same between various models?
My thinking at this point is to create a routine where the AWG output levels are recorded with a good DMM (6500 or 34465A) over the entire 16 bit range, like the NIST approach mentioned in the HP App note based upon Swerleins Algorithm mentioned earlier. This data would be used as a correction factor with the actual desired waveform under test.
Here's an image of 64 channels in operation, a quick single value magnitude calibration was done but not the offset. The offset is reading ~15mv @ 140VPP which is below what we believe we'll need of ~18mv worst case, but with an offset calibration this should drop to a few millivolts. Since we don't know how sensitive the "System" is to these things we've over designed, but do know that a small amount of long term offset can destroy the sensor, folks already found this out
You can see the KS34465A and DMM6500 readings at ~70Vrms, both are using slow filters, smoothing and scaling, and both read ~130uv SD.
Anyway, getting way ahead on myself since this all hinges upon the upcoming demos next month. Now back to writing/editing the Operations and Theory Manuals.
Edit: Update, let the DMM6500 and KS34465A run for a couple hours with a 25Vrms input from the "System", they both agree within 5ppm
Best,