From: pcdhSpamMeSenseless@electrooptical.net   
      
   john larkin  wrote:   
   > On 23 Feb 2026 22:57:00 GMT, Uwe Bonnes   
   >  wrote:   
   >   
   >> john larkin  wrote:   
   >> ...   
   >>> That's about 12 power supplies!   
   >>>   
   >>> My new gadget, the PPG (Precision Pulse Generator) only needs about 7.   
   >>>   
   >>> Interestingly, the most critical one, for noise and drift, is the 1.2   
   >>> volt FPGA core supply. 100uV changes the prop delay more than I like.   
   >>>   
   >>>   
   >> Consider some stabilization loop. Some FPGA TDC design use similar   
   >> approaches.   
   >   
   > I'm designing basically an economy DDG, digital delay generator. So   
   > I'm not investing engineering hours or parts cost on extreme   
   > performance.   
   >   
   > So I'll just make the 1.2v supply as good as we reasonably can and   
   > sell whatever it does.   
   >   
   > Prop delay in the FPGA is about inverse on core power supply voltage.   
   > If the supply is noisy, I don't think we could compensate for that in   
   > real time.   
   >   
   > We will know the PCB temperature so maybe we'll compensate for that a   
   > little. That would be a quick test and a bit of code.   
   >   
      
   Using a backwards PLL to regulate the supply would be pretty amusing,   
   though, you have to admit.   
      
   Cheers   
      
   Phil Hobbs   
      
      
      
   --   
   Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /   
   Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics   
      
   --- SoupGate-Win32 v1.05   
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