martin griffith wrote...
Going by the TI data sheet, the 5534/2 aint that good at 35k, 0.004%
approx, at AV=1 It's almost good enough for my hearing though,.
The AD797 claims to be 0.0003% and the LT1115 don't show graphs going
up above 20K.
I could probably live with 40ppm rather than 25pm (this isn't an audio
app, but rather for instrumentation), but what would be a good choice,
better than the 5532 and not as painful to use as an AD797 or LT1115?
I don't want high Ib, In, Is, Pd, nor do I need the 0.9nV input noise.
But 20V/us and 110MHz GBW should help insure low distortion at 30kHz.
- an hour passes -
I just looked at the LT1468 suggested in the appnote in Fred's post,
it's an improvement over the AD797. Consider, same 2.5ppm distortion
at 30kHz, yet 3nA Ib instead of 250nA, and half the supply dissipation.
I mean, 1/4 watt in an 8-soic is pretty severe, if it's not necessary,
and I'll have 30 of them in this project.
Both opamps use the bootstrapped-output-stage-driver trick, including
the distortion-canceling capacitor Analog Devices talks about (page 8),
but with opposite polarity transistors (a more detailed schematic of
the LT1468 appears in George Feliz' 3-page article in Linear Technology
Magazine, Nov 1998). I also like the LT1468's more reasonable price.
Next I'll examine the pga2310 and pga2311 suggested by ban (although
zipper-noise doesn't worry me, in my instrument the gain settings will
be fixed), one of those may trump the dac8811 + LT1468 combination.
At first glance the 30kHz distortion looks 10x higher, but we'll see.