用于OLED驱动电路的振荡器设计

A Design of Oscillator for OLED Drive Circuit

有机发光二极管(OLED)在不同的工作温度下发光亮度不同,严重影响显示效果。为解决这一问题,需要在驱动芯片中设计温度传感器,实时采样温度信息来调整光亮度。利用带隙基准原理设计了一种输出信号的频率与绝对温度成线性关系的振荡器。通过带隙基准电源产生与绝对温度成正比例的电流,使用该电流对电容充放电以实现信号的振荡。采用CSMC 0.18μm CMOS工艺对电路仿真,电源电压设置为1.8 V,TT标准工艺角,仿真温度设置为0℃时,输出信号频率为3.447 MHz。温度每升高1℃,输出信号的频率增加16 k Hz,可以为OLED驱动电路提供精确的温度信息。

The organic light emitting diode(OLED) has different luminance at different working temperatures,which affects the display effect. In order to solve this problem, it is necessary to design a temperature sensor in the drive chip to provide temperature information. In this paper, an oscillator with a linear variation in the frequency of the output signal with the temperature is designed. The proportional to absolute temperature(PTAT) current generated by a bandgap reference source is charged and discharged to the capacitor to realize the oscillation of the circuit. The CSMC 0.18 μm CMOS process is used for simulation. Under the 1.8 V power supply, the output frequency is 3.447 MHz at 0 ℃ through the TT corner process. When the temperature rises by1 ℃, the frequency of the output signal increases by 16 k Hz, which can provide effective temperature information for the OLED drive circuit.