Just to add to what Gerhard is saying: even an ADC which takes absolute point samples might still have an analog input bandwidth, which is just a limitation of the input amplifier/buffer stage and comparator input. This would act like a low-pass-filter on the front end of the "ideal" ADC. As for acquisition time, that refers to the amount of time during which the sample-and-hold switching element is open in order to charge the sample and hold capacitor. If the input changes during this time, the resulting capacitor voltage will be related to the input signal by a different low-pass-filter function which depends on both the internal R and C values but also the external driving impedance. It is quite possible to have an ADC which samples slowly but takes very accurate approximations to point samples (sample rate of say 1kHz but analog bandwidth of 100s of MHz and an acquisition time of 1 nanosecond). This could be very useful for measuring the amplitude of an RF signal, which you could then use to, for example, AM demodulate the signal. Sean On Tue, Nov 1, 2011 at 1:32 PM, Gerhard Fiedler wrote: > V G wrote: > >> On Mon, Oct 31, 2011 at 9:06 AM, Spehro Pefhany wro= te: >> >>> The acquisition time is to acquire a sample (usually to 1 LSB, though >>> they don't specify). The full power bandwidth is the 3dB down point. >> >> Looks like I'll have to do a lot of reading on ADCs. I don't really >> understand what's going on. > > Most of what they are talking about you find in good datasheets. But > keep in mind that an ADC is an "analog-digital converter" -- meaning > that it has both an analog part and a digital part, and corresponding > specs. > > Terms like acquisition time, sample and samples per second are from the > digital side of things. Terms like bandwidth and 3dB down point are from > the analog side. > > Gerhard > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .