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提出了一种可用于白光LED驱动芯片的电路设计,主要从低噪声、高效率两方面进行设计。采用线性模式控制方法,最大限度减小电荷泵电源电流纹波,从而降低噪声,同时应用多增益工作模式提高不同输入电源电压下的效率。详细讨论了其中带隙电压基准、振荡器及跨导放大器三大模块的电路结构、工作原理和性能特点。采用此电荷泵电路的芯片已在CSMC0.6μm CMOS工艺线投片,测试结果表明,该电荷泵电路工作良好,有效减小了PCB面积和降低了噪声,并且在不同输入电源电压下均能保持较高效率,输出在200 mA时,效率可达92%。
A circuit design that can be used for white LED driver chips is proposed, which is mainly designed from the aspects of low noise and high efficiency. The linear mode control method is used to minimize the ripple of the charge pump power supply current so as to reduce the noise. At the same time, the multi-gain operation mode is used to improve the efficiency under different input power supply voltages. The circuit structure, working principle and performance characteristics of the three modules including the bandgap voltage reference, oscillator and transconductance amplifier are discussed in detail. The chip adopting this charge pump circuit has been cast in a CSMC0.6μm CMOS process line. The test results show that the charge pump circuit works well, effectively reducing the PCB area and noise, and can be maintained under different input power supply voltages Higher efficiency, output up to 92% at 200 mA.