High order low pass filter on the output of LTC1968?

Hi shurp:  Yes the LTC1966/7/8 family is switched-cap so there is output noise and glitching.  You can increase the output C_ave as much as you want (and don't ever omit it).  Also make sure the layout goes onto and off the C_ave; don't connect C_ave through a long stub trace, because that will add inductance.  For further filtering, there are some post filters in the data sheet, but I prefer 3rd order filters for the initial grounded RC.  An initial grounded RC doesn't rely for effectiveness on opamp bandwidth.  A 150kHz 3rd order Butterworth is shown on the back page of the LTC6240 data sheet.  You can just scale the values for lower frequency -3dB point.  Then decide if you want to optimize for settling instead of Butterworth.

Hi shurp:  Yes the LTC1966/7/8 family is switched-cap so there is output noise and glitching.  You can increase the output C_ave as much as you want (and don't ever omit it).  Also make sure the layout goes onto and off the C_ave; don't connect C_ave through a long stub trace, because that will add inductance.  For further filtering, there are some post filters in the data sheet, but I prefer 3rd order filters for the initial grounded RC.  An initial grounded RC doesn't rely for effectiveness on opamp bandwidth.  A 150kHz 3rd order Butterworth is shown on the back page of the LTC6240 data sheet.  You can just scale the values for lower frequency -3dB point.  Then decide if you want to optimize for settling instead of Butterworth.