Noise shaping for switching circuitry

Abstract

Techniques for creating one or more notch frequencies in the power density spectrum of an output voltage generated by switching circuitry. In an aspect, high- and low-side switches are coupled to an output voltage via an inductor. The spectral power of the output voltage at one or more frequencies is estimated, and the estimated spectral power is provided to a switch controller controlling the switches. The switch controller may be configured to switch the switches only in response to detecting that the estimated spectral power at the notch frequency is at a minimum. In certain exemplary aspects, the techniques may be incorporated in an envelope-tracking system, wherein the switching circuitry forms part of a switched-mode power supply (SMPS) supplying low-frequency power to a power amplifier load.

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