Gain=1+R2/R1，VOUT= （1+R2/R1）* (Vin+ - Vin-)
参考：http://www.elecfans.com/dianlutu/187/20171122583615_a.html
https://wenku.baidu.com/view/d47da44edc36a32d7375a417866fb84ae55cc360.html?from=search
https://e2echina.ti.com/question_answer/analog/amplifiers/f/52/t/77884
TI《模拟工程师电路设计指导手册》
http://www.ti.com.cn/zh-cn/analog-circuit/circuit-cookbook.html
