| 摘要 |
<p>A switch mode power supply (SMPS) includes a transformer having primary and secondary windings (3, 4) and means (7, 8) for switching an input voltage across the primary winding (3). The SMPS includes a noise suppressing system comprising a feed-forward system (15, 16, 17, 21) arranged to supply a feed-forward voltage to the transformer secondary (4), the feed-forward voltage being an inverted proportion of the voltage applied to the primary and the feed forward system including a capacitor (19) such that the output from the feed-forward system substantially cancels noise arising in the transformer secondary as a consequence of the interwinding capacitance (Cw) between the transformer primary (3) and secondary (4) windings. The noise suppression system may further include a second capacitor (20A) connected between the transformer secondary and primary DC supply.</p> |
