A -105dBc THD+N (-114dBc HD2) at 2.8VPP Swing and 120dB DR Audio Decoder with Sample-and-Hold Noise Filtering and Poly Resistor Linearization Schemes

📋 论文概要

该论文提出了一种高保真音频解码器，通过采样保持噪声滤波和Poly R技术，解决了DAC参考噪声限制SNR、大输出摆幅下THD+N退化以及高负载电容导致的放大器环路增益失真问题。实现了-105dBc THD+N（-114dBc HD2）在2.8Vpp摆幅和120dB DR的性能。

💡 主要创新点

• 采用采样保持噪声滤波技术有效降低DAC参考热噪声，无需额外功耗。
• 提出Poly R结构，在保持高输出摆幅的同时显著改善THD+N性能。
• 通过优化放大器设计，在高负载电容下维持足够环路增益，降低失真。

🏷 关键词

📄 原文摘要

Three major design issues that arise for high-fidelity audio decoders are: 1) DAC reference noise limiting achievable SNR [1,2]; 2) THD+N degradation at large output swing [3,4]; and 3) Distortion arising from limited amplifier loop gain as a consequence of high output load capacitance (CL) [5]. In the first issue, reference noise along with individual DAC cell noise generally limits SNR for a full-scale signal. The use of large device sizes [1], source degeneration [2] and chopping can mitigate 1/f noise, but none are effective for reducing thermal noise. Consequently, either more power or an external bypass capacitor for noise filtering is necessary for reducing DAC reference noise. In the second issue, THD+N of high-output-swing amplifiers degrades proportionally as the output swing increases above 1.6VPP, even with a 4.5V supply [3,4]. The primary cause of this severe 2nd-order harmonic distortion (HD2) is due to the depletion effect of poly

👥 作者与机构

Shon-Hang Wen, Kuan-Dar Chen, Chuan-Hung Hsiao, Ya-Chi Chen

MediaTek, Hsinchu, Taiwan