【摘要】 介绍了数字电话系统中用户线接口电路的一个重要电路——基于数字信号处理（ＤＳＰ）和ΣΔ调制技术的新一代编解码器（Ｃｏｄｅｃ）。设计了一种带二阶ΣΔ调制器和ＣＭＯＳ能隙基准电压源的四信道Ｃｏｄｅｃ模拟前端，分析了其中关键的过采样ΣΔ调制Ａ／Ｄ转换技术的基本原理。电路采用１．２μｍＣＭＯＳ双层多晶双层铝工艺实现，并利用信号处理数学软件ＭＡＴＬＡＢ和晶体管级电路模拟工具ＨＳＰＩＣＥ完成电路的模拟和验证。单信道模拟前端５Ｖ电源工作，功耗２５ｍＷ，芯片面积约３ｍｍ２。更多还原

【Abstract】 This paper describes an important part of subscriber line interface circuit in digital telephone switching systems the new generation Codec based on DSP (Digital Signal Processing) and ΣΔ modulation technologies. A novel analog frontend of a four channel Codec with second order ΣΔ modulator and CMOS bandgap voltage reference has been designed. The basic principle of the key oversampled sigma delta modulator A/D conversion is analyzed in detail. The circuits are simulated and verified by MATALB and HSPICE simulator with 1.2μm N Well double polysilicon double aluminium CMOS process. The analog frontend operates on a single 5V power subbly, dissipates 25mW. The die area is about 3mm 2.更多还原