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PSoC 5, 3 & 1

Anonymous
Not applicable

I am facing the problem in connecting the resistor  to the circuit ...i send the pic of the circuit and the error too...plz provide some information in how avoid that error.....

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2 Replies
Bob_Marlowe
Expert II

Since your resistors are external parts (as all annotation components are) you have to connect them via pins to the outer world.

   

 

   

Bob

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ETRO_SSN583
Esteemed Contributor

Are you trying to build a simple OpAmp summer ? If you don't need

   
   

the hi Z afforded by the PGAs you can always eliminate them. And

   
   

take your gain individulally for each channel by picking specific input

   
   

resistors. Also offset the OpAmp so circuit works with - values.

   
   

 

   
   

     http://www.ecircuitcenter.com/circuits/opsum/opsum.htm    

   
   

 

   
   

Right now your circuit has a gain of - 1 in the OpAmp summer, referenced to ground,

   
   

hence will not work, eg. output of OpAmp cannot swing below ground w/o you offsetting

   
   

the NI input from something higher than Vss.

   
   

 

   
   

Note dropping PGAs has the additional advantage of less offset and drift. If

   
   

you still need super high Z inputs, have to use PGA, you still have to offset the

   
   

OpAmp.

   
   

 

   
   

Regards, Dana.

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