[time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS

Charles P. Steinmetz charles_steinmetz at lavabit.com
Tue Feb 28 05:13:18 UTC 2012


Ed wrote:

>So, for best HF noise performance where the input noise may be 
>large, it's best to use a follower or shunt regulator topology, 
>despite the lower efficiency - unless efficiency is more important.

To put it more bluntly, the last time I looked (it has been a while, 
so there may be something new I haven't seen) LDOs were all 
substantially inferior to standard regulators in terms of noise 
feedthrough and HF load regulation.  The rule of thumb has always 
been to avoid LDOs unless low dropout was the paramount concern.  Has 
something changed with current LDO designs to make them competitive 
with standard regulators in terms of noise feedthrough and HF load regulation?

Best regards,

Charles









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