PLL Experiments

[Scott Gravenhorst, Synthaholic]

I am new here so I don't know if this subject has been visited 
recently.  Apologies if it was.

I was playing around with a 4046 micropower PLL (connecting it to lock 
to a VCO output) and found that while it will track a VCO very nicely 
without a counter in the loop,  when a divide by N counter (I used div 
by 3) it will lock and frequency multiply only when a rather low freq 
lowpass filter is used.  It tracks, but with a large amount of over and 
undershoot.  The settling time is enormous at something around a half 
second or more.  For my needs, the settling time is too long.  I am 
hoping to reduce this effect to not more than a short chirp.

Have any others of you done this kind of thing?  I am interested in 
frequency multiplication, particularly by 3.  That would allow me to 
generate a perfect fifth without having to dedicate a VCO to that.

- Scott







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