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Wuhan Electronics Components, Materials and Manufacturing Technology Expo 2021

Time:September7-10,2021Venue: Wuhan International Expo Center(Wuhan,China)


027-8485 5755

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  • Sept 7,Tues. 09:00-16:30
  • Sept 8,Wed. 09:00-16:30
  • Sept 9,Thur. 09:00-16:30
  • Sept 10,Fri. 09:00-16:30
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POSITION:HOMENewsIndustry News
Infineon gets better audio with multi-level Class-D amplification

At the heart of the power issue is the amount of energy wasted when switching outputs rail-to-rail when only low audio volumes are required.

Branding its multi-level products Merus, “Infineon is the first company to apply multi-level switching technology to class D audio amplifier products, improving amplifier parameters compared to traditional class D amplifiers  – power consumption, solution size, audio performance, electromagnetic interference, and BOM cost, it said.

It is offering the technology in both single-ended (totem-pole) and bridge (pictured) forms, as well as both fully integrated single-chip and driver-plus-discrete-mosfets forms – across 20W to 2kW per channel.

There is a white paper on the amplifiers, which has this to say of the bridge form, which offers five-level switching:

In a bridge-tied load (BTL) configuration, which is achieved by combining two three-level half-bridges with a switching pattern in which each half-bridge switching pattern is modulated with a 90° phase shift relative to the other, the resulting power stage can provide up to five levels of modulation patterns to a differentially connected speaker load.

Since the resulting output frequency is higher and the individual voltage steps are smaller, this approximates the output audio signal much closer to the input waveform than a conventional class D amplifiers.

A five-level system inherently quadruples the switching frequency at the output nodes the differentially connected speaker load also has much less out-of-band switching residuals. With high efficiency and better EMI and EMC management, the amplifier can thereby effectively be configured for filter-less operation.


In this case, the speaker load switching frequency is four times the switching frequency of the MOSFETs at

the half-bridge output nodes.

The switching pattern gives rise to three states – as opposed to just one in a conventional Class-D amplifier – where complete cancellation of the out-of-band switching residue takes place , namely at -0.5PVdd, 0V and +0.5PVdd. In these states the output of the two half-bridge outputs are either both 0V or they both produce a perfectly ‘mirrored’ 50% duty cycle output.

Although this sentence hints of hidden complexity: ” The capacitor which is “flying” between the top and bottom mosfets is constantly charged by separate circuitry, thereby maintaining a fixed voltage potential.”

As an example of power consumption, the firm claims 250mW at idle for its MA12040 chip, in a circuit that can deliver 40W (into 4Ω from 18V). It comes in analogueand digital  input versions.

Feedback techniques for Class-D amplifiers have to be more elaborate than for linear amplifiers. Merus amplifiers use a fourth-order loop. “A fourth-order loop gives much better gain and thus suppression of error sources compared to the more
traditional second-order loop,” said Infineon, leading to low signal distortion, good audio performance and rejection of power supply noise and ripple.

China (Wuhan) Electronics Components, Materials and Manufacturing Technology Expo, shorted for Electrontech China, was created by Watsonun Exhibition, is to build the platform for electronics engineers. Electrontech China always gather the latest Electronics R&D, Manufacturing and Packaging Technology & equipment, As China's leading exhibition specialized in electronics technology, we welcome you to join us !

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