Hi Andrew, Thanks for the detailed information.
Assuming we have a software register connected to the KatADC atten0 input, how often/fast can we change the attenuation? Thanks, Nimish On Thu, Mar 8, 2012 at 1:03 PM, Andrew Martens <and...@ska.ac.za> wrote: > Hi Nimish > > The katADC is a bit different from the iADC in that it has some RF > components before the ADC. > > The input to the ADC can be terminated to 50Ohms via an RF switch. The > en0 and en1 control this (pulling this low terminates the input). > > There is a fixed 20dB amplifier before each ADC input. > > There is a programmable attenuator in front of each ADC input. The > attenuation is programmable from 0 dB to 31.5 dB in 0.5 dB steps. > atten0 and atten1 control this for each ADC (5 integer bits and 1 > fractional bit). > > The katADC is tuned to toggle 3 or 4 bits with an input of -27dBm and 0 > dB total gain. Because of the 20dB amplifier, care should be taken. > > The way things are set up in the yellow block (take a look under the > mask if interested) is that, directly after ADC configuration, whatever > configuration is specified on these ports is loaded. This allows a > setting to be static, or configurable via a software register. Any > change on these ports causes the new configuration to be loaded > automatically. > > The yellow block does not simulate the action of the RF switch, > amplifier or attenuator. > > Regards > Andrew > > On Thu, 2012-03-08 at 11:24 -0500, Nimish Sane wrote: > > Hi all, > > > > > > Is there any documentation/memo on how to use the KatADC yellow block. > > In particular, I need to know how to use the variable attenuation > > feature (inputs atten*, en*). The documentation here — > > https://casper.berkeley.edu/wiki/KatADC — mentions about a 20dB Gain > > Block (50.0MHz - 850.0MHz), and 0dB to 31.5dB Variable Attenuator > > (controllable in 0.5dB steps). It would be nice to know if someone has > > already figured out how to do it. > > > > > > I believe there is no KatADC tutorial. Does anyone have a model file > > that he/she can share? > > > > > > Also, what should be the power level of the analog signal into the > > KatADC? > > > > > > Thanks, > > > > > > Nimish > > >
