【作者】 周俊；

【导师】 李智群； 梁雪；

【作者基本信息】 东南大学 ， 集成电路工程（专业学位）， 2018， 硕士

【摘要】 直流电源变换器被广泛应用于笔记本电脑等电子设备中,为设备中的各个模块提供持续稳定的电源。通常,直流电源变换器控制芯片的厂商会提供芯片的SPICE模型,以方便设计者预先判断电源系统的性能。但大多数SPICE仿真器无法考虑版图的物理效应,因此,设计者无法预先得知版图寄生效应对最终性能的影响。另外,在严格控制成本的背景下,如何通过设计的优化来减少元件的数量、节省成本也是设计者在设计阶段需要预先考虑的事情。本文选择了笔记本电脑电源中重要而且复杂的CPU核心电源作为研究对象,重点研究了电源传输网络对CPU电源的稳定性和闭环输出阻抗的影响,主要探讨了电源输出电容的优化设计方法。本文选取Intel公司的Broadwell平台的CPU,设计和优化CPU核心电源供电系统,以满足Intel公司的IMVP(IntelMobile Voltage Positioning)规范要求。Intel公司的IMVP规范是基于自适应电压调整(Extended Adaptive Voltage Positioning,EAVP)原理,并针对于CPU的实际工作情况制定的CPU核心电源设计规范。本文中所采用的Intersil公司的ISL95813电源芯片满足IMVP规范。该电源芯片采用了 Intersil公司独有的R3(Robust Ripple Regulator)控制模式,R3控制模式作为一种改进的滞环电流控制(Hysteretic Current Mode Control)模式,相对与传统的脉宽调制模式,其具有更快的瞬态响应速度,和更高的控制精度。首先,通过理论分析CPU电源各子电路的工作原理,建立了系统的小信号模型和电源芯片的平均模型。基于系统的小信号模型,计算出开环增益的传递函数和闭环输出阻抗,经过进一步化简分析,找到了影响相位裕度和输出阻抗的关键因素,以及电源变换器四元件等效模型。利用理论分析结果,完成了电源系统中主要部件的参数设计。将电源芯片的平均模型与使用电磁场仿真工具提取的电源传输网络参数联合放入HSPICE中进行仿真,得到了系统稳定性和电源系统的闭环输出阻抗在考虑电源传输网络寄生效应和不考虑寄生效应时的差异,并在此基础上进行了设计参数的调整。电源输出电容的优化采用了 Sigrity的OptimizePI软件,代入电源变换器四元件等效模型,根据目标阻抗,计算出了优化的输出电容组合和位置布局。最后,实物测试结果表明本文所建立的电源芯片的平均模型准确可信,优化后的实物测试结果与仿真优化结果非常吻合,并且均优于设计指标的要求。本文所阐述的设计优化过程已应用于多个笔记本型号的CPU电源设计中。相同的设计优化方法也可扩展到其它直流电源变换器设计中,方便电源工程师和电源完整性工程师进行协同合作,有效预判电源传输网络的寄生效应对电源系统性能的影响。同时,根据具体的优化需求,对输出电容进行合理的优化。更多还原

【Abstract】 DC-DC converters are widely used in consumer electronic equipment like notebook computers,provide stable power supply for each module.Typically,DC-DC converter control IC manufacturers offer chip SPICE models to facilitate designers to evaluate the performance of power supply system in advance.But most SPICE simulators cannot simulate the physical effects of the layout,so designers could not anticipate layout parasitic effects impact on performance.In addition,in the context of strict cost control,how to design optimized to reduce component quantity or cost are also things designers need to consider in advance during the design phase.CPU core power supply system was chosen as the study object of this thesis,because it’s a typical and complex system in laptop power supplies.The thesis focused on studying PDN(power delivery network)effects impact on the stability and the closed-loop output impedance of CPU power supply,also focused on optimizing design method of output capacitors.This paper selected Intel’s Broadwell platform CPU to design and optimize the CPU core power supply system to meet Intel’s IMVP(Intel Mobile voltage Positioning)specification requirements.Intel’s IMVP specification is based on the principle of EAVP(Extended adaptive voltage Positioning),and a tailored specification for Intel CPU core power supply.The Intersil Company’s ISL95813 was chosen in this paper as power supply chip to meet the IMVP specification.ISL95813 is working based on Intersil’s R3(Robust Ripple Regulator)technology.The R3 modulator as an improved hysteresis current control modulator,has many advantages compared to traditional modulators.These include faster transient settling time,and higher control accuracy.Firstly,small-signal model and average model of VRM(Voltage Regular Module)controller were established by analyzing the behavior of each sub-circuit of VRM theoretically.Based on the small-signal diagram,the transfer function of open-loop gain and closed-loop output impedance were calculated.By further simplifying analysis,the key factors affecting the output impedance and phase margin,as well as an equivalent four-element model of VRM were found.Using result of theoretical analysis,the parameters design of main components of VRM was completed.The average model was used in HSPICE simulation combined with the S-parameters of PDN extracted by electromagnetic simulation tools to reveal the differences of system stability and closed-loop output impedance if considering PDN effects or not,design parameters were adjusted on the basis of this.Optimization of output capacitors was done by using Sigrity OptimizePI software,with VRM equivalent four-element model.Depending on the target impedance,a quantity and layout location optimized scheme of output capacitors was calculated.Finally,the measured test results showed that the average model of the power chip built in this thesis is accurate and credible,and the measured results of optimized CPU core power supply fitted well with the optimized simulation results,and were better than design specification requirements.Design and optimization process described in this thesis has been applied to the CPU core power supply design of several notebook models.Same design and optimization method also can be used on other DC-DC converter designs,facilitate the synergy of power engineers and power integrity engineer on predicting physical PDN impact on power system performance effectively.Meanwhile,according to the specific target of optimization,a reasonable optimization of the output capacitors could be done.更多还原