I was looking to see the effect of switching frequency on dc -dc converters. I found a PowerPoint presentation from On Semiconductor indicating that as we increase the switching frequency of the dc -dc converter, we Avoid frequency bands in which noise would be disruptive
AM Broadcast
Vehicle motion/position monitors
can anyone explain how the switching frequency of the dc-dc converter could affect AM Broadcast or Vehicle motion/position monitors
Small DC/DC converters (several Watts) might be right on the frequency of the AM signals (LW,MW which is roughly 150KHz- 1.7MHz). However, all DC/DC even large ones operating at tens of KHz produce intense high order harmonics due to high speed transients.
A very tight shielding and filtering of DC/DC required to achieve compartibility in that case.
DC-DC converters use high frequency clock- the range can be wide- from 100KHz to 800KHz or so. The clock pulses produce a number of detectable harmonics. If one of these harmonics or sub-harmonics is strong enough to cause desensitization of receiver, the SNR suffers. It may lead to severe degradation in performance.
This is a critical problem and happens due to the non-linearity of circuit modules used in the first IF stage.
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