Design and Development of Library Packages for Mixed-Signal Designs

: Analog to Digital Converters (ADCs) & Digital to Analog Converters (DACs) are called mixed-signal designs. ADC and DAC are also called CODER and DECODER respectively or the CODEC. ADC and DAC are used either for data processing applications or signal processing applications. To design analog to digital converters of data processing applications the normal sampling rate is sufficient whereas for signal processing applications over sampling is necessary since the signal is to be reconstructed well at the output of the receiver. But, the over sample ADC like Sigma-Delta, is limited with the speed. It can give the speed at the maximum of 1Mhz. As it can be observed, even the co-processors of DSP like audio CODEC operate with the speed of hundreds of Mhz. Hence, to eliminate the speed limitation of the oversampled ADC, floating point library packages for adder, multiplier are designed along with shifter to form the floating point Multiplier Accumulator Content (MAC) and will be compiled with the standard library packages of IEEE of any digitally defined simulation tool like Modelsim. Using such newly upgraded mixed signal simulation tool, mixed-signal Integrated Circuits like audio CODECs could be designed.

模数转换器（ADCs）和数模转换器（DACs）被称为混合信号设计。ADC和DAC也分别被称为编码器（CODER）和解码器（DECODER），或者统称为编解码器（CODEC）。ADC和DAC可用于数据处理应用或信号处理应用。对于数据处理应用的模数转换器设计，常规采样率就足够了，而对于信号处理应用，由于要在接收器输出端很好地重构信号，过采样是必要的。但是，像Σ - Δ这样的过采样ADC在速度上是有限的。它的最大速度可达1MHz。可以看到，即使是像音频编解码器这样的数字信号处理器的协处理器也是以数百MHz的速度运行的。因此，为了消除过采样ADC的速度限制，设计了用于加法器、乘法器的浮点库包以及移位器，以形成浮点乘累加器内容（MAC），并且将与任何数字定义的仿真工具（如ModelSim）的IEEE标准库包一起编译。使用这种新升级的混合信号仿真工具，可以设计像音频编解码器这样的混合信号集成电路。