I am looking for a multiplying DAC which I can use to take one sine wave and derive another with precisely controlled relative amplitude for a bridge application. The higher resolution the better, so I'm looking at the 18-bit LTC2756 and the 16 bit AD5543/5. The former has this diagram in the datasheet:
I'm not sure how to read this. Clearly, at 30kHz, there is some capacitive pass-through. But is it:
1) Codes below about 0x0008 have the same output, but above about 0x000F everything is fine, DNL stays good. Or
2) The least significant three bits are the wrong size across the full range, DNL is poor both around 0x0008 and higher.
3) something else?
Relatedly, if this chip won't give me what I want then my next choice is probably AD5543. I can't see an equivalent plot or specification - how do I work out from the datasheet what the DNL is like at 30kHz?
