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Opamp as adder | Cypress Semiconductor

Opamp as adder

Summary: 11 Replies, Latest post by danaaknight on 31 Jul 2012 06:24 AM PDT
Verified Answers: 0
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user_209526657's picture
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41 posts

 Hello,

            i am trying to work opamp as "adder" (adding two analog signals with different frreq) ,but i am facing some errors in connecting resistors to the analog input pins. Please say how to avoid this.

I have shown the schematic diagram and errors in pic

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user_1377889's picture
User
10803 posts

You did not connect your resistors to the annotation-terminal of the pin_1 and pin_2 and the pins are not connected to any wires in the PSoC.

 

Bob

user_14586677's picture
User
7648 posts

If you view the "notice" list after a compile you can double click most error

notices and the error will be highlighted on schematic so that you can easily

identify and correct it.

 

Regards, Dana,

user_209526657's picture
User
41 posts

 now i connected the resistors to the annotation-terminal of the pin_1 and pin_2 and i am giving the two analog signals(inputs) to these Pins ,but still after debug the tool is showing some notes ....i have shown that in pic. how to avoid this notes?

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user_1377889's picture
User
10803 posts

Well, the message states exactly what the situation is: the pin is unconnected.

You are mistaking the "inner" side and the "outer" side of the PSoC: The OpAmp is within the PSoc, all blue components and lines are outsides of the PSoC, so probably you do not need pin_1 and pin_2 and connect your signals to be added directly to your external resistors.

 

Bob

user_209526657's picture
User
41 posts

 It means the resistors which are in the PSoC creator doesn't like resistors in the circuit???

should i connect resistors externally also? 

user_1377889's picture
User
10803 posts

You have got the resistors from the "Annotation" tab in the components window, these are NOT resistors within the PSoC, they are used to clarify / document the external connections of your PSoC design.

You will have to provide these resistors in reality and connect them to your pins and your signals.

Draw a line, everything that is blue is not within your PSoC chip and has to be connected externally.

 

Bob

user_1377889's picture
User
10803 posts

You may even save a pin when you use an internal voltage reference set to GND, look at attached project built with Creator 2.1

 

Bob

user_14586677's picture
User
7648 posts

Your Vref wants to be Vdd/2 or an internal (bandgap) derived Vref (some multiple therof)

in order to maximize OpAmp output swing and place it in its CM range.

 

Regards, Dana.

 

 

user_14586677's picture
User
7648 posts

Somethimg like this, attached.

 

Regards, Dana.

user_209526657's picture
User
41 posts

 Hello,

   My schematic diagram is shown in Pic,In that I am adding two signals ,to get the correct output of “OPAMP”  I should give some offset to the input signals,here output of OPAMP also producing some offset. If I give this output of OPAMP(with some offset) to the ADC I won’t get correct output.

Should I always use some level shifters for every output of a component???

 

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