A Class-D Amplifier with Digital PWM and Digital Loop-Filter using a Mixed-Signal Feedback Loop

Auer, Mario; Karaca, Timucin

doi:10.1109/esscirc.2019.8902785

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…Converting signals to PWM is a task commonly reproduced in recent studies [21][22][23], either to reduce electromagnetic interference [21] or to amplify signals [22][23]. In this work, the function of this conversion is to make the signal amplified by the coil, 𝑉 𝑜 , as understandable as possible, reducing the noise at the input 𝑉 𝑖 .…”

Section: Audio Convertermentioning

confidence: 99%

Projeto de circuito de bobina de Tesla com filtro de áudio FIR / Tesla coil circuit Project with FIR audio filter

Moura¹

2022

BASR

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In this work, the small-signal model and the construction of a high-power transistor circuit similar to Tesla coils, called slayer exciter, are presented. In addition to the hardware design, this article also presents the design of an algorithm that uses an FIR (finite impulse response) filter to convert audio signals into PWM pulses, pulse width modulation, at the input of the circuit, which generate arcs. at the frequency of the input pulse, thus producing music.

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Section: Audio Convertermentioning

confidence: 99%

Projeto de circuito de bobina de Tesla com filtro de áudio FIR / Tesla coil circuit Project with FIR audio filter

Moura¹

2022

BASR

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“…The class-D amplifier [3] is based on a digital pulse-width modulator. It receives digital input data and uses a digital loop filter to reduce distortion and mitigate the need of an analog-to-digital converter.…”

Section: State-of-the-artmentioning

confidence: 99%

An Energy-Efficient Integration of a Digital Modulator and a Class-D Amplifier

et al. 2020

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Energy consumption is always a key feature in devices powered by electric accumulators. The power amplifier is the most energy-demanding module in mobile devices, portable appliances, static transceivers, and even nodes used in underwater acoustic networks. These devices incorporate a modulator, typically a pulse-width modulation (PWM) and a class-D power amplifier, for higher efficiency. We propose a technique to integrate the modulator of a transmitter and PW-modulator of a class-D amplifier to improve the overall efficiency of the system. This integrated set operates as an up-converter, phase modulator (PM), and binary phase-shift keying (BPSK) modulator under certain conditions. The theoretical concept is verified using Matlab and a model is designed and simulated in Simulink. For validation purposes, an electronic circuit is built and tested using Multisim. The results obtained by simulations and circuit implementation show that the proposed integrated system is an energy-efficient and cost-effective solution compared to conventional techniques.

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“…Many ways to apply feedback to digital class-D amplifier have been published in literature [5,6,13,[21][22][23][24][25][26][27][28][29][30]. Hybrid types of amplifiers that generated PWM digitally have been presented where the output stage has an analog loop to mitigate supply variations [5,13].…”

Section: Feedbackmentioning

confidence: 99%

“…However, digitizing the feedback loop is a technique that is becoming possible due to the reduced feature sizes of the required digital logic. A lowpower analog-to-digital converter (ADC) can be inserted into the feedback path to sample the output voltage before [22][23][24][25] or after [6,[26][27][28] the LC-filter, providing a digital representation of the output signal. In [29], one ADC is used to digitize both the input and the feedback signal after summation.…”

Section: Feedbackmentioning

confidence: 99%

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Active PWM ripple reduction in class-d amplifiers using digital loop filters

Lokin¹

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The research field around sound reproduction is driven by a desire to continuously pack more powerful amplifiers in a small fan-less enclosure while providing state-of-the-art noise and distortion performance. Class-D amplifiers are a perfect candidate for these requirements, specifically because of the inherently low dissipation in their switching power stage with respect to more conventional linear amplifiers. There is, however, always a caveat: switching high currents at high frequencies causes electromagnetic emissions that could interfere with the correct operation of other electronic devices. Regulations limit the amount of electromagnetic interference (EMI) that devices are allowed to emit to maintain interoperability between the many electronic devices in the Internet of things (IoT) era.Speakers are commonly connected to an amplifier using leads of several meters. These leads double as an antenna for high frequency signals above the audio band, such as the switching frequency and its harmonics or parasitic ringing in the output stage, thereby causing unwanted radiated emissions. This thesis is focused on reducing the EMI due to the residual power after the output filter at the pulse-width modulation (PWM) frequency, the so called ripple. Examples in literature reduce the power at the PWM frequency and its harmonics by applying spread spectrum modulation to smear power out over a larger bandwidth. However, in this way they still radiate the same amount of power, just not concentrated at distinct frequencies. To reduce the ripple current through the speaker leads, it is possible to use a higher order filter, use a multi-phase or multi-level output stage or to inject a cancellation signal after the output filter. In the research field of power electronics, cancellation schemes have been presented. First the disturbance is sensed and processed and afterwards a cancellation signal is synthesized and injected into the circuit. The processing can be done using a feedback or feed-forward topology, each having its advantages and disadvantages.An extensive case study on multi-phase systems is done to evaluate their merits in reducing the ripple current after the output filter. In a multiphase system, multiple half-bridges are combined in a parallel fashion to drive one or both sides of the load. Interleaving of the PWM carriers in the modulator corresponding to each half-bridge provides a reduction in the observed ripple current after combining the half bridge outputs in the output filter. The effect of adding more phases on the amount of ripple is vii ix ABSTRACT high-frequency poles.In summary, this thesis has shown a technique to reduce the ripple current after the output filter. Thereby the amount of EMI that can be radiated off the speaker leads decreases. The effect of unit delays in the loop has been mitigated by applying a special filter design method to obtain a more stable system. A prototype has been made around an existing amplifier to show the effectiveness of the proposed feedback ripple reduction so...

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A Class-D Amplifier with Digital PWM and Digital Loop-Filter using a Mixed-Signal Feedback Loop

Cited by 4 publications

References 11 publications

Projeto de circuito de bobina de Tesla com filtro de áudio FIR / Tesla coil circuit Project with FIR audio filter

Projeto de circuito de bobina de Tesla com filtro de áudio FIR / Tesla coil circuit Project with FIR audio filter

An Energy-Efficient Integration of a Digital Modulator and a Class-D Amplifier

Active PWM ripple reduction in class-d amplifiers using digital loop filters

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