Abstract
DC-DC buck converters are widely used in portable applications because of their high power efficiency. However, their inherent fast switching releases electromagnetic emissions, making them prominent sources of electromagnetic interference (EMI). This paper proposes a voltage-controlled buck converter that reduces EMI by using a chaotic pulse-width modulation (PWM) technique based on a chaotic triangular ramp generator. The chaotic triangular ramp generator is constructed from a simple on-chip chaotic circuit linked with a symmetrically triangular ramp circuit. The proposed converter can thus operate in the chaotic mode reducing the EMI without requiring any EMI filters. Additionally, using the triangular ramp signal can relax the requirement for a large LC output filter in chaotic mode. The effectiveness of the proposed scheme was experimentally verified with a chaotic triangular ramp generator embedded in a voltage-mode controller buck converter using a 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) process. The measurement results from a prototype showed that the EMI improvement from the proposed scheme is approximately 14.53 dB at the fundamental switching frequency with respect to the standard fixed-frequency PWM reference case.
Highlights
The size of portable/wearable electronic devices is being decreased by integrating circuits, such as analog circuits, high-speed digital circuits, high-speed memories, RF circuits, and antennas, into a single system-on-chip (SoC) or system-in-package (SiP) [1]
We examined the performance of the proposed electromagnetic interference (EMI)-improved buck converter through a simulation
The chaotic ramp generator presented in the previous section was applied to the dual-mode pulse-width modulation (PWM)/pulse-frequency modulation (PFM) buck converter in Figure 1 to examine the EMI reduction performance
Summary
The size of portable/wearable electronic devices is being decreased by integrating circuits, such as analog circuits, high-speed digital circuits, high-speed memories, RF circuits, and antennas, into a single system-on-chip (SoC) or system-in-package (SiP) [1]. It is desirable that these devices be small and light-weight, and have a long battery life. Because of their high power conversion efficiency, switched-mode DC-DC converters are widely used in portable electronic devices [2]. Those problems are serious in SoC/SiP applications that include sensitive blocks, especially RF or sensor circuits [3,4]. Several a posteriori solutions have been proposed to reduce the EMI of DC-DC converters
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