sigmadelta调制器论文一种四阶带通sigmadelta调制器的分析与设计.docVIP

sigma-delta调制器论文：一种四阶带通sigma-delta调制器的分析与设计 【中文摘要】高性能带通sigma-delta调制器是数字中频接收机的核心模块,它和数字降采样滤波器一起完成对中频信号的数字化处理。这样,信道选择和I/Q解调等操作在数字域完成,从而提高了接收机的设计灵活性,减小了电路的设计复杂度,因此成为射频通信领域的研究热点之一。本文基于0.18μm CMOS工艺对一种四阶带通sigma-delta调制器进行了分析和设计。首先,本文介绍了带通sigma-delta调制器的原理和结构,确定设计方案—一位四阶单环多路反馈结构,并在MATLAB/SIMULINK环境下对方案进行了行为级验证。仿真结果表明:峰值信噪比可达到90.5dB,满足设计要求。并基于此给出电路系统中关键模块的主要指标,对后期电路设计提供参考。其次,根据行为级建模提供的系数,基于TSMC0.18μm工艺,采用1.8V电源,200倍的过采样率,80MHz的有效采样频率,对中心频率为20MHz、带宽为200KHz的四阶带通sigma-delta调制器进行了电路级设计,主要包括运算放大器、双延迟型谐振器、一位量化器、反馈延迟和一位DAC电路、时钟产生电路和基准电路。仿真结果表明:峰值信噪比为84.2dB,即有效转换位数为14位,静态功耗为18mW。最后,在电路设计的基础上,对四阶带通sigma-delta调制器进行了版图设计和后仿。其中版图有效面积为:0.7mm*0.4mm;后仿结果表明:信噪比为75dB,基本满足设计要求。 【英文摘要】The bandpass sigma-delta modulator(BP DSM, for short) is the key block of the digital IF receiver. It digitizes the analog signal at an intermediate frequency, together with the digital decimation filter. Thus, the channel election and I/Q demodulation are operated in the digital domain. Then, the flexibility of the receiver is increased, and the complexity of the circuits-designing are relieved. So the bandpass sigma-delta modulator becomes one research focus in the field of RF communication. With the 0.18μm CMOS technology, this paper analyzes and designs a fourth order bandpass sigma-delta modulator.Firstly, the theory and basic structure of sigma-delta modulator are introduced, and the system scheme of a fourth order one bit single-loop multi-feedback is brought forward. Then the behavior model and functionality validation is done in the environment of MATLAB/SIMULINK with the SDToolbox. The simulation results show that the peak SNR arrives 95dB, satisfying the requirement. Besides, the behavior model points out the specifications of the main blocks, providing reference for circuit-level designing.Then, the fourth order BP DSM is designed at circuit-level, with the TSMC0.18 technology and operates with a 1.8V supply voltage. It main consists of the operational amplifier, DD(double-delay) resonator, 1bit qu