新一代数字程控交换机话音编解码电路

New generation speech CODEC for digital telephone switching

为了降低数字程控交换机的成本，提高性能，设计了一种单片４路采用数字信号处理（ＤＳＰ）技术的话音编解码器（ＣＯＤＣＥ）芯片。在该芯片中采用了过采样模数转换技术和ＤＳＰ技术，这些技术有利于充分发挥数字超大规模集成电路（ＶＬＳＩ）的优势，在单个芯片中实现多路话音的编解码，降低交换机成本。同时，采用可编程的数字滤波器，使电路能根据线路具体情况通过软件调整其滤波特性，提高话路性能。芯片用０．５μｍＣＭＯＳ双层多晶三层金属工艺制造，芯片面积约２５ｍｍ２。经测试验证，芯片的各项性能指标均满足ＣＣＩＴＴ的有关标准。

In order to decrease cost and improve performance of Digial Telephone Switching, a four channel CODEC device based on DSP was designed. In this device, oversampled analog to digital converting technique and digital signal processing technique were used. Due to these techniques, it is possible to take the advantages of digital VLSI technique, implement multi channel speech CODEC in a single chip, and make the cost of switching low. Meanwhile, programmable digital filters were used, the performance of the system can be improved just by adjusting the coefficients of the filters by software according to different line characteristics. This device was fabricated in a 0.5μm CMOS process with double poly and 3 layers metal, and integrated on a die size of 25mm 2. Measurements show that all the necessary CCITT's recommendations are fullfilled.