On 1/25/18 7:17 PM, Joseph Gwinn wrote:
On Thu, 25 Jan 2018 21:13:44 -0500, time-nuts-requ...@febo.com wrote:Message: 2 Date: Thu, 25 Jan 2018 16:16:59 -0500 From: John Ackermann N8UR <j...@febo.com> To: time-nuts@febo.com Subject: Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block? Message-ID: <df6ea5f9-50b4-ecef-7eae-a7bc391fb...@febo.com> Content-Type: text/plain; charset=utf-8; format=flowed Yes, I was planning to include bypasses, and I've been convinced to put at least the 1.8V regulator on the board as well. And to think about the interconnects.What I've seen widely done in circuits requiring low phase noise is to have a cascade of regulators, all but the last one (that feeds the RF component in question) beings switchers of different switching frequency, with simple low-pass filters between the regulators, and between the last regulator and the RF component being powered. Between the filtration due to the regulators and that due to the LPFs, one can achieve very large ripple and noise attenuations.
What we've done is switcher from wide range bus (9-24V) to 8V, 60 dB ultimate attenuation low pass, switcher 8V to 5V(e.g.), 60 db low pass, linear with great HF rejection (i.e. the LT3042) to 3V
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