This article presents a Class-D audio amplifier for automotive applications. Low electromagnetic interference (EMI) and, hence, smaller LC filter size are obtained by employing a fully differential multilevel output stage switching at 4.2 MHz. A modulation scheme with minimal switching activity at zero input reduces idle power, which is further assisted by a gate-charge reuse scheme. It also achieves high linearity due to the high loop gain realized by a third-order feedback loop with a bandwidth of 800 kHz. The prototype, fabricated in a 180-nm high-voltage BCD process, achieves a minimum THD+N of −107.8 dB/−102 dB and a peak efficiency of 91%/87% with 8- and 4- $\Omega $ loads, respectively, while drawing 7-mA quiescent current from a 14.4-V supply. The prototype meets the CISPR 25 Class 5 EMI standard with a 5.7-dB margin using an LC filter with a cutoff frequency of 580 kHz.

中文翻译：

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高线性度，低EMI多电平D类放大器

本文介绍了一种用于汽车应用的D类音频放大器。低电磁干扰（EMI），因此更小液相色谱滤波器大小是通过采用4.2 MHz的全差分多级输出级开关获得的。在零输入时具有最小开关活动的调制方案可降低空闲功率，而栅极电荷重用方案可进一步辅助这种空闲方案。由于具有800 kHz带宽的三阶反馈环路实现了高环路增益，因此还实现了高线性度。该原型机采用180 nm高压BCD工艺制造，在8和4频率下，其最低THD + N为-107.8 dB / -102 dB，峰值效率为91％/ 87％。 $ \ Omega $ 从14.4V电源汲取7mA静态电流时，它们分别负载。该原型使用CISPR 25 Class 5 EMI标准，具有5.7dB的余量。液相色谱 截止频率为580 kHz的滤波器。