Frequency dithering systems and methods
AssigneeAnalog Devices, Inc.
InventorsBenjamin Thomas Lampe, Joseph Vanden Wymelenberg
Life of this patent
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Abstract
Described herein are systems and methods that change trigger thresholds between switching cycles such as to prevent constant switching frequencies from creating noise in the audible range. In various embodiments this is accomplished by using different offset values to adjust threshold values of a comparator circuit to generate non-periodic trigger thresholds that are applied to a wake-up circuit.
Claims18
A dithering circuit for low-power applications, the dithering circuit comprising:
- an offset generator configured, in different cycles, to output different offset values;
- and
- a comparator circuit coupled to the offset generator, the offset generator further configured to control the comparator circuit to perform steps comprising:
- receiving threshold values adjusted based on the different offset values;
- and
- using the threshold values to generate a non-periodic output signal, wherein the offset generator is configured to generate, for a first cycle, a first offset and, for a second cycle, a second offset, and wherein the voltage threshold circuit is configured to output, in the first cycle, a first threshold, and, in the second cycle, a second threshold.
A dithering method for reducing audible noise in low-power switching circuits, the method comprising:
- generating a set of offset values that are different from each other, wherein the generating the set of offset values comprises:
- generating a first offset for a first cycle;
- and
- generating a second offset for a second cycle;
- using the set of offset values to adjust a set of threshold values of a comparator circuit, wherein the set of threshold values comprises a first threshold in the first cycle and a second threshold in the second cycle;
- using the set of threshold values to generate a non-periodic wake-up signal;
- and
- using the non-periodic wake-up signal to cause a wake-up circuit to reduce or eliminate one or more audible tones.
A dithering circuit comprising:
- a voltage threshold circuit configured to output a threshold voltage based on an offset that has different offset values in different switching cycles, the threshold voltage having different threshold values in different switching cycles;
- and
- a comparator circuit configured to compare the threshold voltage to a voltage present in an input of the comparator circuit to generate a comparator output, wherein the offset generator is configured to generate, for a first cycle, a first offset value and, for a second cycle, a second offset value, and wherein the voltage threshold circuit is configured to output, in the first cycle, a first threshold value, and, in the second cycle, a second threshold value.
Dependencies are inferred from the claim text.