Composite amplifier using ADA4637-1 and ADA4870-1

I want to build a composite amplifier using the Figure 77 of the datasheet ADA4870-1. It says that the voltage offset is less than 500 uV. I simulate this circuit using LTSpice, when driving ada4637-1 with 0V and monitor the output of ADA4870-1, it is actually 5mV. And the output of the first stage amplifier is ~25 mV.

1. What's wrong with this simulation?

2. Can I achieve better temperature drift (offset and gain) using this composite amplifier architecture?

3. Can I replace ADA4637 with LT6018 or AD8275 for better DC accuracy?

Thanks!



Add composite amplifier to tags
[edited by: byliu at 1:18 PM (GMT 0) on 15 May 2019]