Question Regarding Operational Amps

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SUMMARY

An inverting summing amplifier can accept both positive and negative input voltages, such as V1>0 and V2<0 and V3<0, provided the operational amplifier (op-amp) is powered by split power supplies (e.g., +/-12V). The input voltages must sum to a value that remains within the op-amp's input voltage range. Most voltage summing amplifiers function by summing currents through high resistances at a virtual ground, allowing for negative voltage contributions as long as the total current is positive, effectively enabling current biasing and level shifting.

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ZxcvbnM2000
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Hello ,

i would to ask if it is possible for an INVERTING summing amplifier of three input voltages ( V1,V2,V3) to have some of them negative and some positive i.e V1>0 and V2<0 and V3<0 or any other combination.

Thank you !
 
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ZxcvbnM2000 said:
Hello ,

i would to ask if it is possible for an INVERTING summing amplifier of three input voltages ( V1,V2,V3) to have some of them negative and some positive i.e V1>0 and V2<0 and V3<0 or any other combination.

Thank you !

That should be okay, as long as the opamp is running from split power supplies (like +/-12V), and the input voltages sum to a value that is within the input voltage range of the opamp.
 
Thank you :)
 
Most voltage summing amps are 'really' summing currents through high resistances at a 'virtual earth' so it may not matter that some of the voltage contributions are negative when the PSU is only positive and earth, as long as the sum of currents is greater than zero. That's just the equivalent of current biasing the input appropriately and getting yourself a level shift, effectively.
 
In principle you can have as many input (+/-) voltages as you like as long as their result is within the operating parameters of the op amp...power supply etc
 
truesearch said:
In principle you can have as many input (+/-) voltages as you like as long as their result is within the operating parameters of the op amp...power supply etc
Yes - that's a good way of putting it.
 

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