is that there are specific pins for the PGA ? and how to configure the Pins ?
thank's for answering
Since the routing uses programmable switches internally, there are resistances which have sometimes to be taken into account, There are preferred pins that connect to the OpAmps with low resistors. Easiest would be to let the fitter vhoose the pins for you. When you set the pins manually you'll have to look at the list of preferred usage which is always shown for every port. In the device's analog view you have the opportunity of using an ohm-meter to check the resistances involved.
For completeness: if for some reasons you want to use other pins, thats also possible. But then the resistance to the pins is higher, meaning the OpAmp cannot drive low impedance loads.
i have a question about a this figure below , i make a INSAMP based on three OMPAMP the first PGA1 have a gain of 50 and the PGA2 have a gain of 50 so what is the total gain for the first stage and the second stage ?
Thank's for ansewering.
It Is the product of the gains, but DO NOT make an IA using
PSOC PGA's as the G inaccuracy and tracking inaccuracy
between the two PGAs will destroy your CMRR. Use 3 OpAmps
and external precision thin film R network.
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Also keep in mind if you have a compound G = 2500 then your offsets should
be quite low, and they are not regarding PSOC OpAmps. So do a DC analysis
to start, or PSPICE, then look at noise and PSRR and AC's.
An analysis of why not to use PGAs in IA front end -