为改善传统模拟驱动方式在调亮时会改变OLED灰阶特性的现象，提出了一种可用于硅基OLED驱动芯片的脉宽调制电路（Pulse Width Modulation，PWM）电路。该电路对加在OLED阵列上的共阴极电压进行PWM调制，从而达到在调节亮度时灰阶特性不变的目的。电路采用0.18 μm 1P6M混合信号工艺完成了电路设计和流片验证。仿真和测试结果表明，当亮度从100 cd/m²调节到500 cd/m²时，灰阶特征得到了明显的改善。

In order to improve the gray-scale characteristics when the traditional analog driving scheme is dimmed, a PWM circuit for silicon-based OLED driving chip has been presented. The circuit could modulate the common cathode voltage applied to the OLED array with PWM, so as to achieve the same gray scale characteristics when adjusting brightness. The circuit was designed and verified by the 0.18 μm mix-signal 1P6M CMOS process. Simulation and test results show that when the brightness is adjusted from 100 cd/m² to 500 cd/m², the gray-scale characteristics could be significantly improved.