4 AEF performance with both compensation and damping

With proper compensation and damping, an AEF can achieve significant noise reduction, as shown in Figure 4-1. The measurement with a 440-kHz power converter was conducted, an input voltage of 12 V and an output of 5 V/5 A. Both the AEF and the converter are implemented with the LM25149-Q1. L is 1 µH, C_sense is 100 nF, R_{DC_fb} is 50 kΩ and C_inj is 470 nF. For compensation, 1-kΩ R_comp and 1-nF C_comp are used for low-frequency compensation, and 0.5-Ω R_comp1 and 100-nF C_comp1 are used for high-frequency compensation.

For damping, a resistor and capacitor parallel damping is used; R_damp is 15 Ω and C_damp is 220 nF. As shown in Figure 4-1, the AEF can achieve about 50 dB of noise attenuation at 440 kHz. Compared to a passive filter with similar performance, it is possible to achieve about a 50% size reduction and about a 75% volume reduction [1], [2].