I recently read through the following patent US11316528 PWM DAC with improved linearity and insensitivity to switch resistance that could be interesting for some of you?
Edit: Attached also the previous patent US5402082 for completeness.
-branadic-
Thanks, but that patent looks like it has been written by a robot, not a lawyer. Skimming over it, it looks like Fluke prevents anyone else to use PWM with two switching networks without actually explaining how this addresses errors of (varying) switch resistance, imperfect, varying switch timing, stray capacities in the switches and charge injection. But then, perhaps it is obvious to those skilled in the art. Did anyone grok it and can translate it here to English, pretty please?
I totally agree that that patent is awfully hard to understand - like written to be not understandable. From what I understood it does not really sensible. It kind of has 2 parts: one is claiming good linearity by having some switches insider the OP's loop - however this substitutes the switch resistance by the OPs settling as a weak point. E.g. it is not uncommon to have settling depending on the current and this could cause INL. So I don't think this works. The second point is somehow getting a larger range: not fully sure how it works but somehow the gain would likely depend on the resistors and maybe RC time constant - hard to believe that this would be stable and linear. In that part the switch resistance is not compensated for.
I would not consider the patent relevant, more like smoke screen type to repeat old, expired claims.