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1、深亚微米后端设计流程,许可敬 2009-12-21,Digital Flow Overview,准备工作,工具准备Soc-encounterVoltagestormCeltic fire_icevirtuso Dracula or calibre primetime,文件准备VerilogLEFLIB时序约束文件IO文件DRC，LVS rule 文件,Library Exchange Format(LEF),Timing library,cell(INVX1)cell_footprint:“inv”;area:36.000000;cell_leakage_power:6.883686e+01;
2、leakage_power()when:“A”;value:“60.524918”;leakage_power()when:“!A”;value:“68.836860”;pin(A)direction:“input”;pin(Y)direction:“output”;function:“(!A)”;max_capacitance:0.510000;internal_power()related_pin:“A”;rise_power(“power_outputs_1”);fall_power(“power_outputs_1”)“);,timing()related_pin:”A“;timing
3、_type:”combinational“;timing_sense:”negative_unate“;cell_fall(del_1_7_7)index_1(0.05,0.1,0.3,0.8,1.3,1.9,2.6);index_2(0.0006,0.03,0.06,0.15,0.27,0.39,0.51);values(0.025,0.088,0.149,0.333,0.578,0.827,1.070,0.026,0.096,0.157,0.340,0.586,0.835,1.077,0.015,0.118,0.191,0.373,0.618,0.860,1.104,-0.031,0.11
4、7,0.221,0.456,0.706,0.946,1.187,-0.084,0.092,0.217,0.496,0.790,1.040,1.278,-0.153,0.051,0.193,0.515,0.849,1.132,1.389,-0.235,-0.006,0.155,0.517,0.887,1.207,1.487);fall_transition(del_1_7_7)index_1(0.05,0.1,0.3,0.8,1.3,1.9,2.6);index_2(0.0006,0.03,0.06,0.15,0.27,0.39,0.51);values(0.026,0.118,0.223,0.
5、518,0.920,1.332,1.755,0.035,0.120,0.218,0.518,0.935,1.345,1.756,0.065,0.173,0.251,0.519,0.938,1.321,1.722,0.130,0.291,0.387,0.632,0.951,1.322,1.721,0.181,0.382,0.509,0.784,1.079,1.391,1.742,0.238,0.485,0.626,0.930,1.263,1.566,1.866,0.304,0.595,0.755,1.109,1.464,1.790,2.093);,时序约束文件,create-clock-peri
6、od EXTCL K-PERIOD-name exclkEXTCL K-PORTset-min-pulse-width expr 0.4 3 EXTCL K-PERIOD getclocks exclkset-drive 0 EXTCL K-PORTset-clock-uncertainty EXTCL K-SKEW get-clocks exclkset-clock-latency2source 1 exclkset-max-delay 502from get-ports EXTRST-Pset-input-delay2max 22clock exclk get-ports AASPE-Ps
7、et-output-delay2max 12clock exclk get-ports RPO 3 create-clock2period BUSCL K-PERIOD2name baclk get-ports BACL K-Pset-min-pulse-width expr 0.4 3 BUSCL K-PERIOD getclocksbaclkset-propagated-clock baclkset-dont-touch-network get-clocks baclkset-false-path from get-clocks bdclk to get-clocks exclkset-d
8、ont-touch-network Top-Core/cpu-interface1/reset-intSet_clock_gating_check rise setup 0.1Set_clock_gating_check rise hold 0.2,IO location file,Version:2Offset:19.4700Pin:address14 N 0.4200 0.2800Offset:39.2700Pin:address10 S 0.5600 0.2800,soc encounter 一般流程,Design After input,Top-Level Implementation
9、 Steps,Run timing analysis.Analyze timing with the Common Timing Engine(CTE)using zero net loading to determine whether the initial design meets timing requirements.Place I/O,power,and ground pads.If you provide an I/O assignment file,you are not required to specify the exact location of allI/O pads
10、.Place JTAG(boundary scan)cells.Specify and place JTAG cells near the I/O cells.Once placed,they will not be moved in subsequent placement runs.Place the blocks in the design if you have an all-block.You can use the Encounter block placer or manually place blocks.Critical cell placement.we must plas
11、e some crital cell manually after“JTAG cell placement”this cell like the buffers.Power plan.Define the power rings and stripes.,Top-Level Implementation Steps,Run Amoeba placement.Use the Amoeba placer to place cells in the design.The placer places cells according to module guide and fence constrain
12、ts.Running placement and analyzing the congestion lets you quickly gauge the feasibility of the design in meeting timing and placement density goals.Congestion Analysis Can evaluate the designs congestion,if its results can be acceptable,we can go to next step,othewise must re-do placement optimizat
13、ion.Reorder scan chains.Refine the initial scan-chain order based on Amoeba placement results.Although changes made at this step are not used after the initial floorplanning,this step is still recommended for reducing wire length for a more accurate analysis of congestion.Refine the initial scan-cha
14、in order based on the most recent Amoeba placement results.,After place and power plan,Top-Level Implementation Steps,Build clock tree Define clock tree constraints,such as insertion delay and skew limits.Synthesize the clock tree.Analyze the clock tree reports to determine if timing constraints hav
15、e been met.At this stage,netlist changes are not passed forward.A clock tree is generated to determine clock and timing issues with the current floorplan.Run in-place optimization(IPO).Run in-place optimization,which adds buffer cells,resizes gates,and fixes design rule violations.Although netlist c
16、hanges made at this stage are not kept,in-place optimization is necessary for assessing potential timing issues with the current floorplan.,静态时序分析,静态时序分析技术是一种穷尽分析方法,用以衡量电路性能。它提取整个电路的所有时序路径,通过计算信号沿在路径上的延迟传播,找出违背时序约束的错误,主要是检查建立时间和保持时间是否满足要求,而它们又分别通过对最大路径延迟和最小路径延迟的分析得到。Setup Timing Arc：定义序向组件（Sequentia
17、l Cell，如Flip-Flop、Latch等）所需的Setup Time，依据Clock上升或下降分为2类。Hold Timing Arc：定义序向组件所需的Hold Time，依据Clock上升或下降分为2类。,Top-Level Implementation Steps,Run trial routing.Use the trial router to route the design.Examine the congestion map and the report to identify congested areas.Use the prototyping option of T
18、rial Route to gauge the routability of the design.Extract RCs.Fire&Ice QX ExtractionCreates Standard Parasitics Extraction File(SPEF).Analyze timing to find timing violations.Although timing at this stage is likely to have many violations,you can still discover useful information.Analyze the timing
19、to determine how to alter the floorplan.,Top-Level Implementation Steps,Analyzing Crosstalk Encounter uses either native or standalone CeltIC to perform crosstalk analysis.CeltIC calculates delay to cross-coupling effects on each net and produces delays in the form of a standard delay format(SDF)fil
20、e.This delay is backannotated to Encounter to incorporate delay due to crosstalk effects.Encounter uses NanoRoute to repair noise-on-delay violations using the following techniques:wire spacing,net ordering,layer selection,minimization of long parallel wires,and shielding.Run power analysis.Assuming
21、 that the netlist is clean,use the Encounter engine to run a power analysis,and then use the VoltageStorm power analyzer to run an IR drop analysis.At this point,the block is essentially complete and the rest of the steps involve creating various representations of the block to use during top-level
22、implementation and chip assembly.,Top-Level Implementation Steps,Adding Filler Cells You can add filler cells at the end of the design cycle to fill all the gaps between standard cell instances.Filler cells can also provide decoupling capacitance to complete the power connections in the standard cel
23、l rows and extend N-well and P-well regions.Outputs of Chip Assembly and Sign-off Top-level GDSII Verilog SPEF,Physical verification,GDS导入 将布局布线输出的gds导入virtoso工具，给出对应工艺所需的map文件及标准单元的版图库Label标注 VDD VSS 等其他电源一一标注单独供电需手工处理 PLL PDIODE连接关系需手工加入GDS导出 使用dracula or calibre验证,Physical verification,DRC(design
24、 rule check)设计规则检查 设计规则是集成电路版图各种几何图形尺寸的规范，drc是按设计规则对版图几何形状的宽度间距及层与层之间的相对位置等进行检查。ERC(electrical rule check)电学规则检查 主要检查是否有短路开路和悬空的节点，以及与工艺有关的错误。LVS(layout versus schematic)版图与电路图一致性比较 LVS 是把设计的版图和电路图进行对照和比较，要求两者达到完全一致。ANT天线效应检查 这也是和电路制造过程有关的问题，为了防止太多的电子在铺金属层的过程中集中到导线上击穿栅极，必须保证同层的导线长度不能太长。解决天线效应问题有两种方法，一是在产生天线效应的走线上添加反向二极管，这样可以保护栅极；二是采用向更高层的金属进行跳线连接，这样在加工过程中就可以避免过多电子的积聚。Dummy 插入 为了解决芯片制造时平坦度问题，必须在芯片layout设计时加入dummy pattern/cell,Chip Finishing,
