Why would I want to use a differential op amp configuration while amplifying differential signals?
This is my answer to SE EE question Why would I want to use a differential op amp configuration while amplifying differential signals? My answer Your question is "philosophical" and therefore requires a "philosophical" answer:-) You are actually asking, "What is the idea behind the classic op-amp instrumentation amplifier?" The best way to show it is by reinventing the circuit step by step. Here is my story... Step 1: Single-ended amplifier It is assumed that the two basic circuits of op-amp amplifiers with negative feedback have already been "invented": 1. Non-inverting amplifier 2. Inverting amplifier This is another (no less interesting) story, but now let's just mention the trick with which this was done - in the basic circuits of a follower (K = 1) and inverter (K = -1) an attenuation is introduced in the negative feedback. Compensating for it, they have become amplifiers. Step 2: Imperfect differential amplifier We need a device th...