【作者】 冯守博；

【导师】 吴武臣；

【作者基本信息】 北京工业大学 ， 微电子学与固体电子学， 2008， 硕士

【摘要】 基于∑-△噪声整形技术和过采样技术的数模转换器(DAC)可以可靠地把数字信号转换成为高精度的模拟信号。采用这一结构进行数模转换具有诸多优点,例如极低的失配噪声和高的可靠性,便于作为IP模块嵌入到其他芯片系统中等,更重要的是可以得到其他DAC结构所无法达到的精度和动态范围。在高精度测量、音频转换、汽车电子等领域有着广泛的应用价值。由于非线性和不稳定性的存在,高阶∑-△调制器的设计与实现存在较大的难度。本设计综合大量文献中的经验原则和方法,首先阐述了∑-△调制器的一般原理,并讨论了一般结构调制器的设计过程,然后描述了稳定的高阶高精度调制器的设计流程。根据市场需求,设定了整个设计方案的性能指标,并据此设计了达到16bit精度和满量程输入范围的三阶128倍过采样调制器。本设计采用∑-△结构,根据系统要求设计了量化器位数、调制器过采样比和阶数。在分析高阶单环路调制器稳定性的基础上,成功设计了六位量化三阶单环路调制器结构。在16比特的输入信号下,达到了90dB左右的信噪比。该设计已经在Cyclone系列FPGA器件下得到硬件实现和验证,并实现了实时音频验证。测试表明,该DAC模块输出信号的信噪比能满足16比特数据转换应用的分辨率要求,并具备良好的兼容性和通用性。本设计可作为IP核广泛地在其他系统中进行复用,具有很强的应用性和一定的创新性。更多还原

【Abstract】 Digital-to-analog Convertor (DAC), based on∑-△noise-shaping and over-sampling tech-niques, can convert digital signal to high resolution analog signal reliably. It has many advantages in converting, such as the ultimate low mismatch, high reliability and being able to embed to other SOC as an IP- core module. The more important is its high resolution and dynamic range compar-ing to other DAC structures. Therefore, it is widely used in high-resolution measurements, audio converting, car electronics, and other fields.It is difficult to design and implement a high-order∑-△modulator due to the non-linearity and the non-stability. Based on a synthesis of many empirical principals and methods from refer-ences, the basic principles of∑-△modulator is described in this paper at first. And the design flow of modulator with common structure is discussed. Then, a design flow of stable, high-order and high-resolution modulator is proposed. The performance parameters of such modulator design scheme are specified according to the market requirement. Based on the scheme, a 16-bit resolu-tion, full-scale input range and three-order 128 over-sampling modulator design is accomplished in this paper.∑-△structure is adopted in this paper, the quantization bit, oversampling ratio and order of the modulator are determined following the system requirement. Six bit quantization, three-order single-loop structure modulator is implemented after a deep stability analysis of high-order sin-gle-loop modulator. This design has been implemented and verified on the Cyclone FPGA plat-form, with the real-time audio signal verification. Testing results indicates that the SNR of the de-signed DAC module’s output signals meets the resolution requirement in 16-bit data-convention application, possessing favorable compatibility and universal ability also.The DAC module developed in this paper could be reused as an IP core in other SOC systems, holding strong application performance and innovation.更多还原