Noise shaping for switching circuitry

摘要

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.

主权项

1. An apparatus, comprising:
a spectral estimator configured to estimate a power spectrum of a switching voltage at a first frequency to generate an estimated power spectrum, the switching voltage coupled to an output voltage; and a switch controller configured to control a high-side switch and a low-side switch coupled to the switching voltage based on the estimated power spectrum and a set of switching criteria to reduce the estimated power spectrum at the first frequency, wherein the set of switching criteria is based on a sensed output current of a linear amplifier driving the output voltage, the switch controller configured to:
from a first state wherein the high-side switch is off and the low-side switch is on, transition to a second state wherein the high-side switch is on and the low-side switch is off, based on the conditions that the sensed output current is greater than zero and the estimated power spectrum is at a minimum; andfrom the second state, transition to the first state, based on the conditions that the sensed output current is less than zero and the estimated power spectrum is at a minimum.