【作者】 陈曦；

【导师】 田敬民；

【作者基本信息】 西安理工大学 ， 微电子学与固体电子学， 2003， 硕士

【摘要】 随着社会进步，语音录放专用芯片的用途愈加广泛，因此，对该类专用芯片的研究和设计正日益得到关注。而采用ADM(自适应增量调制)编码的语音录放专用芯片因其简单实用而被广泛研制。 本论文主要设计了一种采用ADM编码的语音专用芯片，完成了ADM编解码器的原理研究、算法设计和电路实现。整个系统包括：内置振荡器，时钟产生器，放大器，前置运算放大器，比较器，AGC(自动增益控制器)，ADM分析综合器，数模转换器以及低通滤波器。设计中采用了一些技术，增大了输入信号的动态范围，减小了电路的规模。其次，为了扩展芯片的应用范围，增加了部分功能电路。 电路设计中，为了便于信号处理以及控制编码精度，采用数字的方法进行量阶和预测码的计算；同时，为了减小电路规模，采用了时分复用的概念，用同一部分数字电路实现量阶调整和预测码的生成，增加了编码精度，减小了电路的规模和功耗。系统中采用差分跨导运算放大器的设计，为了保证其具备高增益与高稳定性，选用二级结构，并且增加了补偿电容和电阻。 设计中，还采用了自动增益控制系统和环路振荡器，以增大信号的输入动态范围以及芯片的应用范围。 整个电路在软件上通过了系统级的仿真。结果表明芯片所实现的设计指标为：预测分辨率10位，采样速率为16Kbps。这个芯片适合于消费类领域。更多还原

【Abstract】 Nowadays, record/playback ICs become more useful, and have optimizing market prospects. For this reason, the study and design of this type of ICs has attracted much attention recently. And the record/playback 1C, using one-bit delta modulation (ADM), has been designed and made widely for its simple production and feasibility.In this paper, a record/playback 1C using ADM is designed systematically. The ADM algorithm is described and implemented with mixed-signal CMOS circuits. The ADM system mainly includes a oscillator, a clock generator, an amplifier, a pre-amplif ier, a comparator, an AGC(Automatic Gain Control), an ADM analyzer&synthesizer, a D/A converter and a lowpass filter. Many circuit design techniques are incorporated into the design of the proposed ADM system so that the range of input signal level can be enlarged and the number of transistors used can be reduced. To extent the use of this 1C, some circuit blocks are added.In the design, digital circuits are used to process the signal and control the precision of coding. And some circuits are used in different time by several functions to reduce the number of transistors used and the dissipation. The 2-stage differential transconductance amplifier is used in the design to achieve high gain. In the design of amplifier, a resisterand a Miller capacitor is used to deal with the stability and frequency compensation. And a AGC system and a ring oscillator are also used.The whole circuit is simulated at system level. It works properly, and verifies the ADM algorithm. Main performance parameters are lObits resolution in prediction coding and 16KS/S sampling rate. The chip can be used in consumer field.更多还原