[time-nuts] Low-pass Filter for 5 and 10 MHz

[Richard (Rick) Karlquist]

Actually, the opposite is true.  Notches have the least phase
shift at the frequency being passed, which is what matters.
It is true that the phase shift at the notch frequency is
uncontrolled, but that is not important.  The HP8662A
had an interesting PLL synthesizer where they had 10 notch
filters for the first 10 harmonics of the sampling frequencies.
This minimized phase shift within the loop bandwidth that
detracted from phase margin.  I designers of the 8662
definitely know what they were doing.

Rick Karlquist N6RK

On 4/11/2013 5:02 PM, Alan Melia wrote:
> Maybe a silly question but isnt the phase response of the filter
> important in this application ?? notches have fairly vicious phase shifts.
>
> Alan
> G3NYK
> ----- Original Message ----- From: "Luciano Paramithiotti"
> <timeok.it at gmail.com>
> To: <time-nuts at febo.com>
> Sent: Thursday, April 11, 2013 5:42 PM
> Subject: [time-nuts] Low-pass Filter for 5 and 10 MHz
>
>
>> A simple low pass filter to cut second and third harmonics from a 5 or 10
>> MHZ signal.
>> See the paper:
>> http://www.timeok.it/files/5_and_10mhz_low_pass_notch_filter.pdf
>>
>> Luciano Timeok
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