Hi! So I am trying to understand op-amps. But before I could learn op-amps, I need to be sure, what an differential amplifier is. I need someone to guide me a bit. Here is the picture I am trying to study. [PLAIN]http://pokit.org/get/b2b5162f1052656a75c035cf8452131b.jpg [Broken] It says here, in Malvino Electronic Principles, that the emitter voltage(AC) is half of the input voltage v1. Why? I understood the the current must be constant at this tail, which contains emitter resistor. Its constant because, there is constant voltage drop across that resistor, and 99% of the Vee is dropped across it, because 2 * 0.7 V of both base-emitter junctions, is negligible. Thanks.