Summing amplifier

116

01:14:05

First stage is an inverting summing amplifier, second stage is a unity gain inverting amplifier to cancel the first inversion.

published 6 years ago

kiani

6 years ago

Your summing amps. Are incorrectly wired. Chk. This. http://everycircuit.com/circuit/5775633060986880

Benjamin6264

6 years ago

The dual inversion is generally preferable to the non-inverting single stage, because you don't have to change resistor values to keep unity gain when adding new inputs to the sum. In your design, the ratio of the resistances at the negative branch would have to change.

Benjamin6264

6 years ago

See https://masteringelectronicsdesign.com/the-transfer-function-of-the-summing-amplifier-with-n-input-signals/

hurz

6 years ago

@Benjamin6264, check all your links again. Your inverter are not working, they are schmitt triggers. Swap input terminal or you are in big trouble

kiani

6 years ago

All fine... But look closely at your circuit. You have placed tge feedback resistor on the wrong side.. Only oscillators have positive feedback.. Adders hsve negative f/b.. Your circuit f/b residtors should be connected to - ve i/p (s) of the opapms. I just eanted to shoe the two configerations of inv. And non inv. Adders..

kiani

6 years ago

Here two inverting adders, cascaded. http://everycircuit.com/circuit/5775633060986880

Benjamin6264

6 years ago

D'oh! Opamps have been flipped to correct wiring.

Benjamin6264

6 years ago

Is there a good explanation as to why the simulation was behaving the same?

kiani

6 years ago

If you chrck out all the voltages and currents you will see differences. Chk this. http://everycircuit.com/circuit/5917331917373440

hurz

6 years ago

@kiani, unfortunately the wrong wirering behaves IDENTICAL with the correct one. But only as long we stay in linear operating range. If we leave it by e.g. overdrive it will turn out to be what it actually is. A Schmitt Trigger.

hurz

6 years ago

Test it yourself. I have in creased the gain of both stages. Start and see it quickly traps into a schmitt trigger with a hysteresis it does not get out with help. Correct the wiring of the first stage and run again. And finaly correct the last stage. Because of more gain per stage it saturates but is not trapped into a hysteresis. Get it? http://everycircuit.com/circuit/5002896168189952

kiani

6 years ago

Yes exactly, seems one acts ss gate keeper and don' t let the other to get out, unless they both have as much money and power.

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