The QFN has the advantage of multiple power pins so VDD interactions can be avoided via use multiple Vdd pins for 2 outputs per Vdd pin instead of all outputs on a single pin.? Improvements in general can be made by using the lowest possible output drive current (which may not be feasible, depending on application) or by adding a buffer on each output (undesirable added complexity)? by significantly minimizing output current that each output buffer has to drive and thus minimizing ground bounce interactions as well as VDD interactions if only a single VDD pin is available.
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-Steve K1RF
------ Original Message ------
Date 10/20/2024 11:39:06 AM
Subject Re: [QRPLabs] Why The EER Method For SSB Generation Works
On Thu, Oct 17, 2024 at 12:05 PM, Jerry Gaffke wrote:
I've often thought we might get less phase noise if we spent?
another dollar on the Si5351 in a QFN package with its
multiple Vdd's and better grounding.? Any comments?
?
I'm not aware of any data to support this thesis, but it might be true under specific circumstances. There's a lot of factors that go into determining the ultimate jitter performance, including how the device is programmed, the drive strength, power supply noise, board layout, impedance, etc.
?
The Si570 has much, much better jitter performance albeit at a much, much higher price. It's too bad the price of the Si570 has not scaled like the Si5351.
?
73,
Scott
AK5SD
