Digitally assisted EMI-reduction techniques for Class-D amplifiers with digital control

Auer, Mario; Karaca, Timucin

doi:10.1109/emccompo.2017.7998077

Cited by 5 publications

(12 citation statements)

References 9 publications

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“…A key difference of this technique with respect to the other modulation techniques [3]- [7] is that the power is removed from the spectrum, instead of being spread out over neighboring frequencies. Another advantage compared to classic AB/D amplifiers is the high gain at f PWM , which is made Fig.…”

Section: A Active Ripple Reductionmentioning

confidence: 99%

“…To make a visualization of the poles and zeros, values have to be substituted in (3). A demo board with the 'AX5689' [20] is used to implement the filter and the audio amplifier.…”

Section: Filter Synthesismentioning

confidence: 99%

“…Several studies have been done to reduce EMI in Class- D amplifiers, for instance in automotive electronics and to allow filterless operation in mobile devices. Three techniques are seen in literature, namely, switching frequency modulation [3]- [5], CM modulation [3], [6], [7] and Class-AB/D [8]- [13]. Switching frequency modulation (FM) of the PWM carrier is done by modulating the system clock or the triangle carrier wave.…”

Section: Introductionmentioning

confidence: 99%

“…Switching frequency modulation (FM) of the PWM carrier is done by modulating the system clock or the triangle carrier wave. Modulation is done using a triangle pattern in [3], or a uniformly distributed pseudo-random spread spectrum signal in [4] and [5]. These techniques are applicable for both AD and BD modulation.…”

Section: Introductionmentioning

confidence: 99%

“…By randomizing the switching pattern for the zero-output level, the CM power is spread over a larger frequency range and consequently, EMI is reduced. In [3] the randomization is done using a pseudo-random sequence. A more advanced method is used in [6], where the pseudo-random sequence is noise shaped, specifically to have notches around defined AM radio frequencies.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

EMI Reduction in Class-D Amplifiers by Actively Reducing PWM Ripple

Lokin

Zee

Schinkel³

et al. 2020

IEEE Trans. Circuits Syst. I

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Class-D amplifiers switch high voltages and currents at high frequencies and hence produce electromagnetic interference (EMI). This work presents a technique to reduce the high frequency ripple, which is still present after the output filter. A Class-A ripple reduction amplifier is put in parallel to the output of the Class-D amplifier, each having their own feedback loop with digital filters. High ripple reduction loop gain is achieved at the PWM frequency by using a resonator as digital loop filter. Dissipation in the Class-A amplifier is reduced by using a low common-mode signaling technique. Commonmode and differential-mode switching components at the PWM frequency are reduced by 27 dB and 18 dB respectively. Total system efficiency is 79% at 40 W output power.

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Section: A Active Ripple Reductionmentioning

confidence: 99%

“…To make a visualization of the poles and zeros, values have to be substituted in (3). A demo board with the 'AX5689' [20] is used to implement the filter and the audio amplifier.…”

Section: Filter Synthesismentioning

confidence: 99%