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提出了一种用于D类放大器的新型频率抖动电路。采用流控模式和容控模式相结合,利用周期数字频率调制,使能量原本集中的频谱分散到离散频率点上,从而使频谱幅度降低,减小D类放大器EMI的辐射。基于0.5μm CMOS工艺,对提出的频率抖动电路进行仿真验证。结果表明,频率抖动点具有很好的均匀性和线性度,并且D类放大器的EMI峰值幅度下降约13 dB;高频频谱连续,扩频效果显著,频率抖动电路面积约840μm2,消耗的最大电流仅为1.2μA。
A new frequency dithering circuit for class D amplifier is proposed. The use of flow control mode and capacity control mode, the use of digital periodic frequency modulation, the original concentration of the energy spectrum is scattered to discrete frequency points, so that the spectral amplitude decreases, reducing the Class D amplifier EMI radiation. Based on the 0.5μm CMOS process, the proposed frequency jitter circuit is verified by simulation. The results show that the frequency dithering point has good uniformity and linearity, and the peak amplitude of EMI of Class D amplifier is reduced by about 13 dB. The high frequency spectrum is continuous and the spreading effect is remarkable. The frequency jitter circuit area is about 840μm2. The maximum current consumed Only 1.2μA.