sigma delta oversampling rate.
sigma delta oversampling rate.
(OP)
I have a couple of questions on sigma delta converters. I hope someone can help.
If I need 10 bits of resolution, what oversampling rate do I need? I've seen in the literature that 64x should give 10 bits. Does this mean a total of 640 bits from the analog portion of the converter? I've seen it implied that 64 bits from the analog portion should give 10 bits. This doesn't make any sense to me, as if I put in the voltage equivalent to a digital 1, it takes 512 samples for the integrator to even detect the signal.
Any help or insight would be appreciated.
JJM2
If I need 10 bits of resolution, what oversampling rate do I need? I've seen in the literature that 64x should give 10 bits. Does this mean a total of 640 bits from the analog portion of the converter? I've seen it implied that 64 bits from the analog portion should give 10 bits. This doesn't make any sense to me, as if I put in the voltage equivalent to a digital 1, it takes 512 samples for the integrator to even detect the signal.
Any help or insight would be appreciated.
JJM2





RE: sigma delta oversampling rate.
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RE: sigma delta oversampling rate.
RE: sigma delta oversampling rate.
I am trying to get 10 bits of accuracy from a single bit, 1st
order sigma delta. My real question relates as much to the digital portion as to the analog.
How many samples from the 1 bit converter are required to get 10 bits of resolution after filtering and decimation?
Some of the literature I have read implies that you can use 64 bits from the analog portion to get 10 bits of output resolution through the filtering/decimation process. It appears to me that the minimum number of samples to get "10" bits of resolution is 513. The very first sample, assuming the sigma delta is cleared every conversion point gives you the MSB. You then need 512 more to get the value to the LSB. This doesn't seem quite right either though, since you can just use an adder to calculate the output. (essentially an LPF w/ 512 taps)
When I ran the AD simulator (linked above) It also took the 512 samples to measure a digital 0000000001 equivelent input.
Any thoughts or insight?
Thanks
RE: sigma delta oversampling rate.
RE: sigma delta oversampling rate.
Thanks,
JJM
RE: sigma delta oversampling rate.
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TTFN
RE: sigma delta oversampling rate.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com