说明：  经典的四电阻差动放大器似乎很简单，但其在电路中的性能不佳。本文从实际生产设计出发，讨论了分立式电阻、滤波、交流共模抑制和高噪声增益的不足之处。
(The classic four resistor differential amplifier seems very simple, but its performance in the circuit is poor. In this paper, the shortcomings of discrete resistor, filter, AC common mode suppression and high noise gain are discussed from the practical production design.)