DAC8 as Reference to a PGA

Question: I am using the output of a DAC8 as reference to a PGA, but it does not work. What could be the reason?

 

Answer:

The DAC is formed by a Switched Capacitor block whose output is switching in nature (Refer AN2041 for details of the theory of operation of a switched capacitor block).  In order to have a continuous output from a switched capacitor block, the output has to be passed through a Sample and Hold circuit which is present in the Analog Out Bus.  So, to connect the output of a DAC to a PGA, it has to be first connected to the Analog Bus and then to the PGA.