Abstract
This study presents a high-fidelity and high-efficiency digital class-D audio power amplifier (CDA), which consists of digital and analog modules. To realize a compatible digital input, a fully digital audio digital-to-analog converter (DAC) is implemented on MATLAB and Xilinx System Generator, which consists of a 16x interpolation filter, a fourth-order four-bit quantized delta-sigma (ΔΣ) modulator, and a uniform-sampling pulse width modulator. The CDA utilizes the closed-loop negative feedback and loop-filtering technologies to minimize distortion. The audio DAC, which is based on a field-programmable gate array, consumes 0.128 W and uses 7100 LUTs, which achieves 11.2% of the resource utilization rate. The analog module is fabricated in a 0.18 µm BCD technology. The postlayout simulation results show that the CDA delivers an output power of 1 W with 93.3% efficiency to a 4 Ω speaker and achieves 0.0138% of the total harmonic distortion (THD) with a transient noise for a 1 kHz input sinusoidal test tone and 3.6 V supply. The output power reaches up to 2.73 W for 1% THD (with transient noise). The proposed amplifier occupies an active area of 1 mm2.
Highlights
Following the rapid development in artificial intelligence Internet of ings, smart speaker and TWS headset based on class-D audio power amplifiers (CDAs) have become the most popular portable audio products
E modulation techniques of CDAs can be divided into uniform-sampling pulse width modulation (UPWM) [2,3,4], pulse-density modulation (PDM) [5,6,7], click modulation [8, 9], and zero-position coding with separated baseband [10, 11]. e CDAs comprise several main topologies. e open-loop architecture requires a precise carrier signal to achieve low distortion [12]. e closed-loop architecture does not require a similar precise carrier because the CDA loop gain suppresses the carrier distortion [13]
We propose a CDA with a closed-loop negative feedback and loop-filtering technologies to improve the total harmonic distortion (THD) and suppress the noise introduced by the power supply
Summary
Following the rapid development in artificial intelligence Internet of ings, smart speaker and TWS headset based on class-D audio power amplifiers (CDAs) have become the most popular portable audio products. E closed-loop architecture does not require a similar precise carrier because the CDA loop gain suppresses the carrier distortion [13]. Some CDAs generally comprise a single-bit quantizer, but ensuring stability over all modulation indexes requires high controller power [14, 15]. Multibit quantizers can improve the stability of delta-sigma (ΔΣ) modulators they entail high quiescent power and considerable complexity [16]. To overcome these drawbacks, we propose a CDA with a closed-loop negative feedback and loop-filtering technologies to improve the total harmonic distortion (THD) and suppress the noise introduced by the power supply.
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