Integrated Class-D Audio Amplifier With 95% Efficiency and 105 dB SNR

Jiang, Xicheng; Song, Jungwoo; Cheung, Darwin; Wang, Minsheng; Arunachalam, Sasi Kumar

doi:10.1109/jssc.2014.2335713

Cited by 21 publications

(7 citation statements)

References 17 publications

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“…In these applications, the active power components are operated as switches in order to achieve a high power efficiency and PWMs are needed to control these switches. Using PWM control, some state-of-the-art circuits achieve power-efficiency figures in excess of 95% [1].…”

Section: Introductionmentioning

confidence: 99%

Digital pulse-width modulator with spread-spectrum emission reduction

Karaca

Auer

2018

Elektrotech. Inftech.

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Pulse-width modulated power-stages are used in many power-electronic applications because of their high efficiency. They are known to be a root cause for electromagnetic emission problems if no countermeasures are taken. This work presents a digital pulse-width modulator with an emission reduction method based on spread-spectrum modulation techniques. The proposed method is analyzed in detail, and two possible digital implementations are discussed. The implementations are compared in terms of chip-area and power consumption. Finally, an application of the proposed digital pulse-width modulator in a digitally-controlled Class-D audio amplifier is presented to show the feasibility of the concept. Using an FPGA prototype, a measured emission reduction of up to 9.5 dB is achieved.Keywords: pulse-width modulator; spread-spectrum modulation; electromagnetic emission; Class-D amplifier Digitaler Pulsweitenmodulator mit Spread-Spectrum-Emissionsreduktion. Pulsweitenmodulierte Leistungsstufen werden aufgrund ihres hohen Wirkungsgrades in vielen leistungselektronischen

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Section: Introductionmentioning

confidence: 99%

Digital pulse-width modulator with spread-spectrum emission reduction

Karaca

Auer

2018

Elektrotech. Inftech.

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“…In the last decades, high power audio amplifiers have been widely used in our life [1]. The goal of amplifiers is to reproduce the input signal with the desired power and quality in the output [1].…”

Section: Introductionmentioning

confidence: 99%

“…The goal of amplifiers is to reproduce the input signal with the desired power and quality in the output [1]. Audio amplifiers can be categorized in 5 groups: (1) class-A amplifiers, that consist of a simple Bipolar Junction Transistor (BJT), which is shown in Figure 1, (2) class-B amplifiers, (3) class-AB amplifiers, (4) class-C amplifiers, and (5) class-D amplifiers [2].…”

Section: Introductionmentioning

confidence: 99%

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Design of Novel Low-Power and High-Efficiency Class-d Audio Amplifier

Hajhashemkhani¹,

Karimi²,

Rezai³

2017

IJCA

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“…The CM control loop is utilized in the closed-loop PWM CDA to suppress power-supply noise and even HDs. Moreover, input feedforward to the internal node of the loop filter of the CDA is employed to further enhance the linearity of the CDA [5]. As a result, the internal nodes of the loop filter are input-signal independent and the non-linearity of the loop filter has less effect on the linearity of the CDA.…”

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confidence: 99%

5.2 A 118dB-PSRR 0.00067%(−103.5dB) THD+N and 3.1W fully differential class-D audio amplifier with PWM common-mode control

Wang

Lin

2016

2016 IEEE International Solid-State Circuits Conference (ISSCC)

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A high power-supply rejection ratio (PSRR) and high-linearity Class-D audio amplifier (CDA) becomes important as the CDA is directly connected to a battery supply for efficiency considerations in mobile phone applications. Several closed-loop pulse-width-modulation (PWM) CDAs with high PSRR (>90dB) have been published recently. In conventional PWM fully differential CDAs [1,2], these designs are focused on increasing differential loop gain to improve PSRR. However, the PSRR is mainly limited by feedback gain-matching, that is, resistor matching of the feedback network; hence, it is difficult to achieve PSRR >80dB for yield >99%. In [3], a pseudo-differential structure composed of two singleended opamps is adopted to achieve PSRR >90dB. Nevertheless, it suffers from 3dB noise increase as compared to the fully differential counterpart. Moreover, unity-gain bandwidth (GBW) of single-ended opamps is usually smaller than that of fully differential opamps due to the design trade-off between noise and the location of current-mirror poles; hence, it results in low in-band gain and high total harmonic distortions (THDs) of pseudo-differential CDAs. As for linearity, conventional PWM CDAs suffer from poor linearity due to in-band aliasing tones. In the uniform PWM (UPWM) architecture [4] that achieves THD+N of around -96.5dB, a sinc function, realized by using a sample-and-hold circuit in front of the loop filter, is applied to avoid the signal-dependent intermodulations folding back in-band. However, high switching frequency is required and the power consumption is increased.In this work, a 1 st -order PWM common-mode (CM) control loop is introduced in the fully differential CDA to overcome the design challenge of PSRR and linearity. Input feed-forward with passive summing is employed to reduce internal swing and signal-dependent terms to further enhance linearity. A singleamplifier-biquad technique is adopted to reduce the number of opamps for further power reduction. The CDA achieves 118dB PSRR and 0.00067% (-103.5dB) THD+N. It delivers maximum output power of 3.1W into a 4Ω load under 5.5V battery voltage.Figure 5.2.1(a) depicts a linear model of a conventional closed-loop fullydifferential CDA. With the gain mismatch, δ, of the differential feedback path, the supply noise and even harmonic distortions (HDs), denoted by e C , contribute (δ×e C ) to the differential output (v OP -v ON ). The differential-mode noise and odd HDs, denoted by e D , are suppressed by the loop gain H(s). PSRR can only be improved by reducing δ while a stringent matching requirement of δ<0.001% is required in order to achieve PSRR >100dB. As shown in Fig. 5.2.1(b), a CM control loop is adopted to suppress e C . The derivation shows that e C is further suppressed by the loop gain of the CM control loop, H C (s). The supply noise and even HDs at the CDA output are improved from (δ×e C ) to (δ×e C /H C ). Consequently, the CM control loop is of great help to improve the PSRR and reduce the THD of a fully-differential CDA.Figure 5.2.2 shows the sy...

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Integrated Class-D Audio Amplifier With 95% Efficiency and 105 dB SNR

Cited by 21 publications

References 17 publications

Digital pulse-width modulator with spread-spectrum emission reduction

Digital pulse-width modulator with spread-spectrum emission reduction

Design of Novel Low-Power and High-Efficiency Class-d Audio Amplifier

5.2 A 118dB-PSRR 0.00067%(−103.5dB) THD+N and 3.1W fully differential class-D audio amplifier with PWM common-mode control

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