# Differential amplifier basics

I an differential amplifier whether, inputs are out of phase or outputs or out of phase , Please explain I think the inputs must be in phase to get the difference of each other? Thanks in advance

• I suggest that you take a piece of paper, draw a sinewave on it, then under sine 1 draw an identical 2nd sinewave sine 2, then a 3rd sinewave which has 180 degrees phase lag compared to the first sine. Now draw sine 1 - sine 2 and draw sins 1 - sine 3. Those are the differential signals. Which one is useful to amplify? – Bimpelrekkie Jun 17 at 17:14
• Sir in my case I always considered the case of sine signals of two different magnitudes of amplitudes, then both the signals are useful for amplification – sai sri datta Jun 17 at 17:32
• Please u can correct me now – sai sri datta Jun 17 at 17:32
• I always considered the case of sine signals of two different magnitudes of amplitudes, then both the signals are useful for amplification What makes you use two different magnitudes? What is the point? Then it isn't a pure differential signal anymore. But if you insist on making your own life harder, by all means do so. – Bimpelrekkie Jun 17 at 19:03
• We are having trouble understanding exactly what you are asking. If doing the exercise on paper isn't enough, then show us your work and from that concrete example we'll try to confirm your impressions, or correct any misunderstandings. – TimWescott Jun 17 at 19:03