From: jl@glen--canyon.com   
      
   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.   
      
      
   John Larkin   
   Highland Tech Glen Canyon Design Center   
   Lunatic Fringe Electronics   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)