Re: Propagation delay sensitivity to temperature, voltage, and manufacturing
This is what I had sent dirctly to the poster, a few days ago. Maybe
it's of general interest:
First I have to warn you about using a DCM output as ADC clock. Experts
agree that the ADC clock should be as jitter-free as possible, and a
DCM output has significant jitter, which costs you dearly in raising
the ADC noise floor. I shudder thinking about the jitter = noise you
feed into the ADC.
Regarding the more benevolent aspect of delay change: Delay increases
with temperature.
in some cases delay is proportional to the absolute (Kelvin)
temperature. In some cases it is more stable.
I think you can measure it, and more conveniently:
Build a ring oscillator (feedback with a single inversion) of
equivalent snippets of delay and LUTs, and then measure the frequency
as function of temperature. You get tremendous resolution and thus
accuracy.
My advice, give the ADC a clear clock, then use the DCM to adjust the
phase. And minimize routing and gating.
Peter Alfke Xilinx Applications
.
Relevant Pages
- Re: Translating an embedded C algorithm
... I agree with other posters that simply translating this function into Ada does not give a good comparison between C and Ada. ... The C function deals with two kinds of data: ADC readings and temperatures expressed in deci-degrees Celsius ... The ADC count-type does not depend on temperatures, and the temperature type does not depend on the ADC, so I would define these types in different packages, so: ... Also, it handles separately the case where the Index becomes the last index of the calibration table, where I think the C code uses Index+1 incorrectly as an index to the Table. ...
(comp.lang.ada) - Re: Translating an embedded C algorithm
... I'm using a small C function that does temperature ... measurement by linear interpolation of a lookup table as an example. ... -- AdcCount Raw ADC count. ... function MeasureTemperature(AdcCount: Adc_Reading) return ...
(comp.lang.ada) - Re: ADC Interpolation Gain
... In addition to Tim's points on clock jitter, etc., another parameter ... that may be useful in an RF system is the aperture jitter or aperture ... the ADC and comes into play mostly if you're doing IF-sampling, ... The one will kill your signal strength without touching your noise, the other will act like phase noise, spreading out both your signal and interfering signals. ...
(comp.dsp) - Re: Bias value of Canon DSLRs?!
... offset is 128 on a 12 bit ADC then the total offset is only 3% of the entire analogue range and needs adjustment with a precision of only 0.25%. ... Analogue signals are simply not that precise or consistent and will vary by far more than this with age and over the operating temperature range of the unit. ...
(rec.photo.digital) - Re: ADC Interpolation Gain
... particular attention to when choosing the correct ADC? ... Look for converters that specify their 2nd- and 3rd-order ... Jitter is important, but shows up as phase noise in your receiver -- ... relatively narrow-band PSK signals that occupy about 1-LSB (or a ...
(comp.dsp) |
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