上拉晶体管（PMOS）

一种P沟道金属氧化物半导体（PMOS）晶体管，专门配置为推挽放大器输出级中的上拉元件。该器件作为高端开关，在激活时向负载提供电流，与下拉NMOS晶体管互补工作，提供高效的双向电流驱动，并最小化交叉失真。

通过施加负的栅源电压（Vgs < 0）在源极和漏极之间形成导电沟道。当栅极电压相对于源极足够负时，晶体管导通，将正电源电压连接到输出。在推挽配置中，它在输入信号的正半周导通，而互补的NMOS晶体管处理负半周，从而实现高效的B类或AB类放大，并降低功耗。

Operates by applying a negative gate-to-source voltage (Vgs < 0) to create a conductive channel between source and drain. When the gate voltage is sufficiently negative relative to the source, the transistor turns ON, connecting the positive supply voltage to the output. In push-pull configurations, it conducts during positive half-cycles of the input signal while the complementary NMOS transistor handles negative half-cycles, enabling efficient Class B or AB amplification with reduced power dissipation.