From the curves, spurs level are lower for the 14 bit DAC (depending on
the frequency).
There will be no specific problem to use 2x AD9859 in quadrature a priori.
I agree with you the AD9958 is very attractive but sounds out of the
amateur scope in term of soldering.
Anyway I never tested the "soldier paste"...
73, Gérard/F6EHJ
[EMAIL PROTECTED] a écrit :
>Looks like the AD9951 part is gaining in popularity in a dual
>configuration and I was wondering why the AD9859 part couldn't be used in
>a dual configuration ? Does it not have the same lower spur level ?, it's
>a 10bit DAC, cheaper, etc. I would also think the AD9958 dual part offers
>too many package problems (for me anyway) with it's LFCSP vs the other
>TQFP. Since my applications are digital and I look for the high speed
>comparators like on the AD9952, what's a good external comparator to use
>?
>
>73 Kees K5BCQ
>
>
>----- Forwarded Message -----
>From: "mdgolfbum" <[EMAIL PROTECTED]>
>To: [email protected]
>Date: Fri, 12 May 2006 21:13:49 -0000
>Subject: [soft_radio] QSD direct to A/D
>Message-ID: <[EMAIL PROTECTED]>
>
>I've been reviewing the NC2030 schematic and watching the activity
>on HPSDR.org. It appears that a CW SDR lashup that would work is a
>dual 9951 for quadrature VFO, LVDS squarer, 3125 with ~1uf
>integrating caps and then directly into a 24bit a/d such as the
>CS5381.
>
>The input impedeance requirements of the 5381 normally require
>buffering but the low output impedance of the mixer appears to
>satisfy that directly. The signal levels appear to be in the
>ballpark as well.
>
>The dual 9951 should give the best currently available spur
>performance and a stable quadrature output.
>
>The nice part about this is that it requires no additional amps to
>introduce noise and nonlinearity.
>
>The 5381 isn't a full 24bit and has input noise but seems like it
>might be an interesting point along the way especially if the
>sampling rate is kept low.
>
>Note that I'm assuming that the bandwidth presented to the A/D is
>~1Khz and the DDS is doing the tuning rather than a spectrum type
>display which requires much greater sample rate that the HPSDR folk
>are pursuing.
>
>The PC or DSP would then be responsible for controlling the 9951
>frequency including any phase tweaks and providing the audio signal
>processing for additional filtering and compression.
>
>Are the available software bits capable of processing in this more
>limited way?
>
>thoughts?
>
>jim ab3cv
>
>
>
>
>
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>
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