EMRFD Message Archive 2505

Message Date From Subject
2505 2008-12-14 11:56:07 Giancarlo PA3AKE Project Update - DDS
Hi all,
I have been talking to Colin Horrabin, G3SBI, and we spoke about the
good work Meirtein Bakker, PA3AKE, is doing on his high performance
analog front-end receiver using the H-Mode Mixer.
Martein is a very good research engineer and amateur radio. With his
knowledge, determination and attention, using homemade test equipment
and a W&G spectrum analyzer he has identified a design problem in the
AD9910 which will probably also affect the AD9912 and other recent
DDS chips by ADI. Colin was able to talk to Analog Device high speed
DDS group in North Carolina. There was a great deal of reluctance to
accept Martein's findings. Eventually they were able to duplicate his
results and they were very grateful to Martein because the same
mistake will not be made in their new designs. We have a very low
phase noise with ADI 9910-12 DDS but we are discovering AM noise !!!!
a problem not present with the AD9951.
As Colin stated, the remarkable thing is that it has taken an amateur
radio state of the art receiver project to identify this and it has
not been found by Analog Devices big customers with all their high
tech test equipment.
The bad news is that it is unlikely there will be a chip revision,
even though the fix is simple unless there is pressure from a major
customer. Maybe this is a good pressure some of our colleagues could
apply to ADI from their engineering key positions.
Analog Devices is a company we all have a lot of respect for. The
high speed DDS chips are a major technical achievement and are useful
to our hobby as Martein will show. During chip development the design
team probably paid too much attention to results from their high tech
measuring equipment when by design it rejected a device parameter
they should also have been looking for.
Martein has just published an update to report on the evaluation of
the AD9910 DDS chip to be used as the DDS-Local Oscillator that
complements the Down Conversion Frontend. The research regarding the
AD9910 and especially its noise characteristics is finished. Those
interested can visit his web page:


73 and with the occasion Season's Greetings
2512 2008-12-19 15:10:34 Bob Larkin Re: PA3AKE Project Update - DDS
Hello - I just had a chance to look at the PA3AKE DDS story. Just
great work! We have all admired this and related projects, for some
while. And, this research
2563 2009-01-02 08:15:07 Giancarlo PA3AKE Project Update - DDS
Hi All,

First of all, Happy New Year 2009 and wish you the Best on your radio
activities and projects.

I like to inform you that our friend Martein, PA3AKE, has updated his
web page on high performance analog front-end.
See the below sub-directories where you will find a lot of
information and measurements on DDS.

Local Oscillator:

o Impact on Dynamic Range
o Design Choices
„X 1GHz Reference Clock
„X AD9910 Prototype Board
„X AD9910 and SSB-Noise
„X AD9910 and PM-Noise

o Sideband Noise Measurement
„X Reciprocal Mixing
„X Crystal Notch Filter
„X Quadrature Mixing

Best 73 and enjoy the visit