  Two-stage wireless power receivers, which typically include an AC-DC diode
rectifier and a DC-DC regulator, are popular solutions in low-power wireless
power transfer applications. However, the interaction between the rectifier and
the regulator may introduce beat frequency oscillation on both the DC-link and
output capacitors. In this paper, the cause of the beat frequency oscillation
and its related issues are investigated with the corresponding design solution
on alleviating the oscillation discussed. Theoretical and experimental results
verifying the presence of beat frequency oscillation in the two-stage wireless
receiver system are provided. Our study shows that the beat frequency
oscillation can be significantly alleviated if appropriate design solutions are
applied.
