Spurious-Noise-Free Switching Power Converter
For Information, Contact:
Jay Bjerke
Commercialization Manager, Engineering
Web Published:
ISU researchers have developed a new control scheme for switching power converters that makes them suitable for powering noise-sensitive loads, such as analog and RF (radio frequency) applications.

Development Stage:
The converter has been demonstrated to eliminate spurs and have a very low noise floor when implemented in 0.35 ┬ÁM standard CMOS technology, and ISU is seeking partners interested in commercializing this technology.

Switching power converters are extensively used in electronic devices because of their high power conversion efficiency. However, the spurious output noise they create due to periodic switching precludes their use for noise-sensitive loads—particularly analog and RF load types. Traditionally, linear regulators have been used to mitigate this problem, but can result in much lower power efficiencies. Spread-Spectrum control techniques, such as Σ-Δ and Δ modulation, can be used to reduce the spurious noise in switching power converters, but result in large wide-band increase in the noise floor, while random frequency hopping techniques reduce the spur level at the expense of generating multiple additional spurs. To overcome these drawbacks, ISU researchers have developed a new PWM control scheme for switching regulators that combines phase chopping with random frequency hopping to achieve completely spur-free operation, while delivering low output noise floor with no sub-harmonics due to hopping. The proposed architecture is very attractive for designing generic low-noise power supplies for spur-sensitive loads, as well as loads sensitive to the random noise floor without post linear regulation, extra passive filtering, or customization for each load. This results in much better power efficiency and reduced implementation size and cost. Moreover, since spur-elimination is based on the fundamental switching behavior of the regulator, spur-free operation is accomplished not only at the output, but at every node in the regulator including the input power and ground rails and the substrate. This significantly reduces Electromagnetic Interference (EMI) and facilitates integration of switching regulators in mixed-signal Systems-on-Chip (SoCs) without interfering with other sensitive circuits that share the same substrate or power rails. The performance achieved by this novel control scheme makes switching power converters suitable for directly powering many noise-sensitive analog and RF applications, such as RF mixers, RF Low Noise Amplifiers, and RF Power Amplifiers. Additionally, the proposed architecture can be used for implementing class-D amplifiers with reduced EMI filters, and supply modulators for RF Polar Power Amplifiers. The proposed scheme constitutes minimal area, power, and design effort beyond traditional single-switching-frequency PWM-controlled design, and can be easily incorporated with an already existing regulator.

• Versatile (has utility for many noise-sensitive applications)
• Economical (reduces size, cost and power consumption)
• Efficient (obviates the need for post filtering stages and may extend battery life in portable applications)
• Integrate-able (can be easily integrated on the same chip with other noise-sensitive circuits without affecting their performance)
Switching power converters; power amplifier supply modulator

Patent Information:
*To see the full version of the patent(s), follow the link below, then click on "Images" button.
Country Serial No. Patent No. Issued Date
United States 13/397,251 8,901,905* 12/2/2014

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