Hi,
I can't help with Cadence...
But take care by joining two ADC with a MUX.
A MUX may add voltage spikes caused by charge injection ... at every switching edge.
Adding (indeed averaging) two ADC outputs with the use of two resistors does not add spikes.
It lowers the inividual ADC error by 6dB and may increase speed / time resolution.
... just as an alternative idea....
Klaus
.. and with the MUX method: if both ADCs do not perfectly match you will see a square wave overlaying your signal.
Example: both ADCs should continously output 1.000V .... with a given sampling rate.
But one ADC has an offset error of 0.004V.
The MUX result will be: 1.000V | 1.004V | 1.000V | 1.004V | 1.000V | 1.004V | 1.000V | 1.004V |...
While the resistor method will give 1.002V without ripple