16- Agenda S-Parameters and Linear Analysis 4 Transmission Lines and Field Solver 5 IBIS 6 DAY 2 Synopsys 60-I-032-BSG-005 © 2007 Synopsys, Inc. All Rights Reserved

26- Unit Objectives After completing this unit, you should be able to: Describe what IBIS models are Use IBIS models 2

36- Unit Objectives This is an Instructor Guide page! Switch to "Notes" view.

46- What is IBIS? IBIS = I/O Buffer Information Specification IBIS is a standard for describing the analog behavior of the buffers of digital devices using plain ASCII text formatted data IBIS files are not really models; they contain the data that will be used by the simulation tools behavioral models and algorithms IBIS started in the early 90’s to promote tool independent I/O models for system level signal integrity work 3

56- What is IBIS? This is an Instructor Guide page! Switch to "Notes" view.

66- IBIS Model Characteristics Fast simulation: V / I / t relationships for only external nodes of the entire buffer No circuit detail involved: Not useful for circuit designers Ideal for system level interconnect design Hides process and IP Package modeling Electrical Board Description Multi-stage buffer: [Driver Schedule] 4

76- IBIS Model Characteristics This is an Instructor Guide page! Switch to "Notes" view.

86- IBIS Buffers A basic IBIS model consists of: Four I-V curves  Pullup & POWER clamp  Pulldown & GND clamp Two ramps  dV/dt_rise  dV/dt_fall Die capacitance  C_comp Packaging  RLC values For each buffer on a chip 5

96- IBIS Buffers This is an Instructor Guide page! Switch to "Notes" view.

106- IBIS Buffer Block Diagram 6

116- IBIS Buffer Block Diagram This is an Instructor Guide page! Switch to "Notes" view.

126- Buffer Output Model 7

136- Buffer Output Model This is an Instructor Guide page! Switch to "Notes" view.

146- IBIS Model I-V Curves (1/2) [Pulldown] referenced to [Pulldown Reference]: Contains the difference of drive and receive (3-state) model I-V curves for driver driving low Origin of the curve is usually 0V for normal CMOS buffers [Pullup] referenced to [Pullup Reference]: Contains the difference of drive and receive (3-state) model I-V curves for driver driving high The origin of the curve is usually the supply voltage (Vcc or Vdd) 8

156- IBIS Model I-V Curves (1/2) This is an Instructor Guide page! Switch to "Notes" view.

166- IBIS Model I-V Curves (2/2) [GND Clamp] referenced to [GND Clamp Reference]: Contains the receive (3-state) model I-V curves The origin of the curve is usually 0v (GND) for normal CMOS buffers [Power Clamp] referenced to [Power Clamp Reference]: Contains the receive (3-state) model I-V curves The origin of the curve is usually at the supply voltage (Vcc or Vdd) 9

176- IBIS Model I-V Curves (2/2) This is an Instructor Guide page! Switch to "Notes" view.

186- IBIS I-V Curve Rules of Thumb Generally, I-V curves will be from –Vdd to 2*Vdd: The theoretical max overshoot due to full reflection is 2X the signal swing Current is positive when flows into the device GND Clamp range is –Vdd to Vdd Power Clamp range is Vdd to 2*Vdd 10

196- IBIS I-V Curve Rules of Thumb This is an Instructor Guide page! Switch to "Notes" view.

206- Ramp and V-t Curve Measurements The [Ramp] and [Rising Waveform], [Falling Waveform] keywords describe the transient characteristics of the buffer: Information on how fast the pullup and pulldown transistors turn on and off with respect to time Die capacitance ( C_comp ) is included Package effects are not included 11

216- Ramp and V-t Curve Measurements This is an Instructor Guide page! Switch to "Notes" view.

226- Schematic of an I/O Circuit Example of a simple link simulation using I/O buffer IBIS Buffer model used to replace transistors W-element used to model transmission line 12

236- Schematic of an I/O Circuit This is an Instructor Guide page! Switch to "Notes" view.

246- IBIS Buffer Basic Syntax BufferName node1 node2 …nodeN + file=‘/fullpath/file.ibs’ + model=‘modelName’ Number of nodes depends on types of buffer Node sequence is predefined for each supported buffer type 13

256- IBIS Buffer Basic Syntax This is an Instructor Guide page! Switch to "Notes" view.

266- Supported Buffer Types and Syntax (1/2) Input buffer B_INPUT nd_pc nd_gc nd_in nd_out_of_in Output buffer B_OUTPUT nd_pu nd_pd nd_out nd_in [nd_pc nd_gc] Tr B i-state buffer _3STATE nd_pu nd_pd nd_out nd_in nd_en [nd_pc nd_gc] Input/Output buffer B_IO nd_pu nd_pd nd_out nd_in nd_en V_out_of_in [nd_pc nd_gc] Input ECL Buffer B_INPUT_ECL nd_pc nd_gc nd_in nd_out_of_in Output ECL Buffer B_OUTPUT_ECL nd_pu nd_out nd_in [nd_pc nd_gc] Tristate ECL Buffer B_3STATE_ECL nd_pu nd_out nd_in nd_en [nd_pc nd_gc] 14

276- Supported Buffer Types and Syntax (1/2) This is an Instructor Guide page! Switch to "Notes" view.

286- Supported Buffer Types and Syntax (2/2) Input-Output ECL Buffer B_IO_ECL nd_pu nd_out nd_in nd_en nd_out_of_in [nd_pc nd_gc] Terminator Buffer B_TERMINATOR nd_pc nd_gc nd_out Series Buffer B_SERIES nd_in nd_out Series Switch Buffer B_SER_SW nd_in nd_out Open Drain, Open Sink, Open Source Buffers Same as output buffer Open drain and open sink buffers do not include pull-up circuitry but, always specify nd_pu Open source buffers do not include pull-down circuitry but, always specify nd_pd I/O Open Drain, I/O Open Sink, I/O Open Source Buffers Same as input-output buffer I/O open drain and I/O open sink buffers do not include pull-up circuitry but, always specify nd_pu I/O open source buffers do not include pull-down circuitry but, always specify nd_pd 15

296- Supported Buffer Types and Syntax (2/2) This is an Instructor Guide page! Switch to "Notes" view.

306- BUFFER Keyword buffer = {buffer_number | buffer_type} Buffer numbers INPUT = 1 OUTPUT = 2 INPUT_OUTPUT = 3 THREE_STATE = 4 OPEN_DRAIN = 5 IO_OPEN_DRAIN = 6 OPEN_SINK = 7 IO_OPEN_SINK = 8 OPEN_SOURCE = 9 IO_OPEN_SOURCE = 10 INPUT_ECL = 11 OUTPUT_ECL = 12 IO_ECL = 13 THREE_STATE_ECL = 14 SERIES = 15 SERIES_SWITCH = 16 TERMINATOR = 17 16

316- BUFFER Keyword This is an Instructor Guide page! Switch to "Notes" view.

326- BUFFER Keyword Example Examples: b2 nd_pu nd_pd nd_out nd_in nd_pc nd_gc + file = '.ibis/at16245a.ibs‘ + model = 'AT16245_OUT‘ + buffer = 2 b2 nd_pu nd_pd nd_out nd_in nd_pc nd_gc + file = '.ibis/at16245a.ibs‘ + model = 'AT16245_OUT‘ + buffer = output 17

336- BUFFER Keyword Example This is an Instructor Guide page! Switch to "Notes" view.

346- TYP Keyword typ={typ|min|max|fast|slow} typ={0|-1|1|2|-2} If the value of typ is either typ, min, or max, it signifies a column in the IBIS file from which the data is extracted: The default is typ=typ If min or max data are not available, typ data is used If the value of typ is fast or slow, combinations of the min and max data will be used Typ can also be set to a number -2Slow 2Fast 1Max Min 0 Typ 18

356- TYP Keyword This is an Instructor Guide page! Switch to "Notes" view.

366- Power On | Off Power = On (default): HSPICE connects buffer to power sources specified in IBIS file Do not connect the external nodes (nd_pu, nd_pd, nd_pc, nd_gc) to voltage sources in the netlist Do not use SAME external node name in different buffer Power = Off: Must connect the external nodes to voltage sources or through parasitic RLC elements to simulate power and ground bounce 19

376- Power On | Off This is an Instructor Guide page! Switch to "Notes" view.

386- INTERPOL and NOWARN Keywords INTERPOL: Interpol={1|2} The I-V and V(t) curves need to be interpolated The recommended default interpolation method is linear interpolation interpol = 1 Interpol=2 uses quadratic bi-spline interpolation NOWARN: Suppresses warning messages from the IBIS parser Do not use as the first keyword after the nodes list 20

396- INTERPOL and NOWARN Keywords This is an Instructor Guide page! Switch to "Notes" view.

406- XV_PU and XV_PD Keywords Enable state variable information of pullup and pulldown nodes: xv_pu = state_pu xv_pd = state_pd State variable information can be printed:.print v(state_pu) v(state_pd) 21

416- XV_PU and XV_PD Keywords This is an Instructor Guide page! Switch to "Notes" view.

426- RAMP_FWF and RAMP_RWF Keywords Used to select which ramp or waveform data to use from the available data Ramp_fwf controls falling waveforms or ramp: ramp_fwf= {2|1|0} Ramp_rwf controls rising waveforms or ramp: ramp_rwf= {2|1|0) Default is ramp_fwf=2 and ramp_rwf=2: The first two waveforms found in the model will be used 0 denotes use the ramp data specified in the model 1 denotes use one waveform: If more than one waveform is available, the first waveform found in the model is used 22

436- RAMP_FWF and RAMP_RWF Keywords This is an Instructor Guide page! Switch to "Notes" view.

446- FWF_TUNE and RWF_TUNE Keywords Control the algorithm for processing ramp and waveforms: Default value is 0.1 Value range is from 0 to 1 Used only if ramp_fwf and ramp_rwf are 0 or 1: fwf_tune = fwf_tune_value rwf_tune = rwf_tune_value 23

456- FWF_TUNE and RWF_TUNE Keywords This is an Instructor Guide page! Switch to "Notes" view.

466- C_Comp C_comp normally is connected between the output pin (input pin for input buffers) C_comp can be split between the pullup, pulldown, power and ground clamps using the keywords: c_com_pu= c_com_pd= c_com_pc= c_com_gc= If C_comp is split between the pullup, pulldown, power and ground clamps and the total exceeds the C_comp value specified in the IBIS model, HSPICE will continue the simulation and not give a warning 24

476- C_Comp This is an Instructor Guide page! Switch to "Notes" view.

486- IBIS Buffer Scaling Keywords All I-V and V-t curves can be scaled: Default for all scaling factors is 1 Values must be greater than 0 I-V curves scale buffer strength V-t curves scale buffer delay, rise and/or fall time Pullup and pulldown scaling factors: pu_scal= pd_scal= Power and ground clamp scaling factors: pc_scal= gc_scal= Rising and falling waveform scaling factors: rwf_scal= fwf_scal= Supply voltage variation scaling factors: spu_scal= spd_scal= 25

496- IBIS Buffer Scaling Keywords This is an Instructor Guide page! Switch to "Notes" view.

506- HSP_VER Keyword The default is the current version of the HSPICE simulator Use to set to previous version of the IBIS buffer Syntax hsp_ver = hspice_version 26

516- HSP_VER Keyword This is an Instructor Guide page! Switch to "Notes" view.

526- Using the.IBIS Command (1/2) A buffer is added to the netlist for every pin Follows the signal_name and model_name defined in the [Pin] list of the IBIS file Buffers not created for POWER, GND or NC pins The.IBIS command creates new buffers in the netlist Buffer_name = ‘cname’_‘pin_name’’  Cname is defined in the.ibis card in the netlist  Pin_name is defined by the [Pin] keyword in the.ibs file 27

536- Using the.IBIS Command (1/2) This is an Instructor Guide page! Switch to "Notes" view.

546-.IBIS Command Syntax (2/2) Buffer pin names Die side output node, if package model used: 'cname'_'pin_name'_o Output node or input node for input buffers: 'cname'_'pin_name' Enable node for buffers with enable pins: 'cname'_'pin_name'_en Input node or outofin node for input buffers: 'cname'_'pin_name'_i Outofin node for buffers other than input buffers: 'cname'_'pin_name'_outofin 28

556-.IBIS Command Syntax (2/2) This is an Instructor Guide page! Switch to "Notes" view.

566-.IBIS Command Syntax (1/2).IBIS cname + file=‘file_name’ + component=‘component_name’ + package=[3|0|1|2|] + pkgfile=‘pkg_file_name’ + Keywords Cname - Instance name of the.IBIS command in the netlist File_name - IBIS model file name Component - define using the [Component] keyword in the IBIS model file Note: The component name and file name are case-sensitive 29

576-.IBIS Command Syntax (1/2) This is an Instructor Guide page! Switch to "Notes" view.

586-.IBIS Command Syntax (2/2) Package – (optional, default is 3) defines package parasitics to be added to each pin 0 - does not use package parasitics 1 - use [Package] definition from the IBIS model file 2 - use [Pin] definition from the IBIS model file 3 – use the [Package Model] if it is defined in the IBIS model file  If [Package Model] is not defined, the [Pin] model will be used  If [Pin] is not defined, the [Package] model will be used  Package Model can be defined in either the IBIS file or the PKG file Pkgfile – defines file containing package model file Required if package model is not defined in the IBIS model file Optional Keywords – any valid B-element optional keyword 30

596-.IBIS Command Syntax (2/2) This is an Instructor Guide page! Switch to "Notes" view.

606-.IBIS Command Examples Examples:.ibis memory + file = ’dram.ibs’ + component = ’SIMM’ + package = 2.ibis p_test + file = ‘comp.ibs’ + component = ‘cpu_133mhz_ff’ + package = 3 + pkgfile = ‘test.pkg‘ + typ=typ nowarn 31

616-.IBIS Command Examples This is an Instructor Guide page! Switch to "Notes" view.

626- Using the.PKG Command (1/2) Syntax.PKG pkgname + file = ’pkgfilename’ + model = ’pkgmodelname’ Where Pkgname – package card name Pkgfilename – name of the.pkg or.ibs file that contains package models Pkgmodelname – package model defined by [Define Package Model] in the.pkg file or [Package Model] in the.ibs file 32

636- Using the.PKG Command (1/2) This is an Instructor Guide page! Switch to "Notes" view.

646- Using the.PKG Command (2/2) Example:.pkg fp1 + file=‘ddr2tst.pkg + model=‘flatpack1’ The.PKG command automatically creates a series of either lumped RLCs or distributed RLCs Package pin names Nodes on the die side: ’pkgname’_’pinname’_dia Nodes on the pin side: ’pkgname’_’pinname 33

656- Using the.PKG Command (2/2) This is an Instructor Guide page! Switch to "Notes" view.

666- Using the.EBD Command Describes a PCB or substrate that can contain components or other boards through a set of user visible pins The Electrical Board Description (EBD) file describes the electrical connectivity The.EBD command is used in conjunction with the.IBIS command because the EBD file contains the reference designator of the component HSPICE automatically creates lumped RLCs or W-elements to express the paths Examples of use: SIMM, DIMM Modules MCMs Processor Modules Packages 34

676- Using the.EBD Command This is an Instructor Guide page! Switch to "Notes" view.

686-.EBD Command Syntax.EBD ebdname + file = ’ebd_filename’ + model = ’ebd_modelname’ + component = ’ibisname:reference_designator’ + … Keywords Ebdname – ebd card name Ebd_filename – name the.ebd file that contains the board description Ebd_modelname – ebd model defined by [Begin Board Description] in the.ebd file Ibisname - Name of the associated.IBIS command to identify IBIS buffer component Reference_designator - Reference designator from the node subparameter of the [Path Description] in the ebd file Note: The filename and modelname are case sensitive 35

696-.EBD Command Syntax This is an Instructor Guide page! Switch to "Notes" view.

706-.EBD Example.ebd mb1 + file = ’memsimm.ebd’ + model = ’16X8 SIMM’ + component = ’mem:u21’.ibis mem + file = ’mem16x8.ibs’ + component = ’SIMM’ + package=3 + pkgfile=‘fpsim.pkg’ Pin names Pins associated with the board will be named ebdname_pin_name Where  Pin_name is the pin name given in the [Pin Description] of the ebd file 36

716-.EBD Example This is an Instructor Guide page! Switch to "Notes" view.

726- EBD Example Example from IBIS 4.0 specification 37

736- EBD Example This is an Instructor Guide page! Switch to "Notes" view.

746- EBD Limitations No coupling between paths No correct modeling of differential signaling Transmission line parameters have to be derived with respect to well defined reference planes Insufficient connector modeling 38

756- EBD Limitations This is an Instructor Guide page! Switch to "Notes" view.

766- Using the.ICM Command ICM = IBIS Interconnect Modeling Specification “Interconnect” can be connector, cable, PCB traces or even an IC package  Defines structure as path between “sections”  Defines the electrical data for each section Connector Stub Connector T-line Described by [Begin ICM Model] … (path description) … [End ICM Model] Described by [Begin ICM Section] … (RLGC or S-params) … [End ICM Section] Connector Stub T-line 39

776- Using the.ICM Command This is an Instructor Guide page! Switch to "Notes" view.

786- ICM Structure (1/2) Header Information [Begin Header] and [End Header] keywords Spec. Version Filename and Revision Date Source, Notes, Disclaimer and Copyright ICM Family Description of model “family” or group List of models in the “family” 40

796- ICM Structure (1/2) This is an Instructor Guide page! Switch to "Notes" view.

806- ICM Structure (2/2) ICM Model Description Type (SLM, S-parameter, MLM_*, etc.) Signal-to-ground ratio & (optionally) reference Z Tree Path Description  Links groups of signals through cascaded “sections” of model data  Describe one-to-one connections between sections and ports or endpoints of the interconnect  Allows “forks” with same number of conductors Nodal Path Description  Links sections of model data through input & output nodes per section  Connections need not be one-to-one –Allows internal “dangling nodes” Nodal and Tree Path Descriptions are mutually exclusive 41

816- ICM Structure (2/2) This is an Instructor Guide page! Switch to "Notes" view.

826- Additional ICM Constructs ICM Pin Map Maps connector pins to Tree Path Descriptions ICM Node Map Maps connector pins to Nodal Path Descriptions ICM Section Data block for model sections Data is in RLGC matrix or S-parameter format  Matrices include self-inductance, capacitance, conductance, loss, etc.  Similar format to IBIS package models Each section is referenced by at least one Tree or Nodal Path Description 42

836- Additional ICM Constructs This is an Instructor Guide page! Switch to "Notes" view.

846- ICM Swath Allows minimal, economical description to be used for larger connectors or interconnects Smaller electrical parameter matrices can be repeatedly mapped over a larger structure Includes the [ICM Swath Description] and [ICM Swath Pin Numbers] keywords 43

856- ICM Swath This is an Instructor Guide page! Switch to "Notes" view.

866-.ICM Syntax.icm icm_name + file=‘filename.icm' + model=‘xxx‘ + Keywords File – specify particular ICM file to include Model – specify which model in the file Swath – indicate which method is used to expand swath matrix 1. Centering the swath around the pins of interest 2. Expand and Centering - Expanding the swath matrix into a larger swath matrix, centering both swaths about the paths of interest 3. Expand to full sized interconnect 44

876-.ICM Syntax This is an Instructor Guide page! Switch to "Notes" view.

886-.ICM Example Example:.icm icmtreemodel + file = 'test_001.icm' + model = 'dynamite' 45

896-.ICM Example This is an Instructor Guide page! Switch to "Notes" view.

906- Multi-Lingual Model Support (1/2) Supports SPICE or Verilog-A buffer model Syntax: B_SPICE node1 node2 node3 … + file='ibis_filename' model='model_name' + [nd_in=node_input] + [nd_en=node_enable] + [nd_outofin=node_out_of_in] + [typ={typ|min|max}] [power={on|off}] + [nowarn] + [para_begin para1=value1 para2=value2 … para_end] 46

916- Multi-Lingual Model Support (1/2) This is an Instructor Guide page! Switch to "Notes" view.

926- Multi-Lingual Model Support (2/2) Buffer element nodes must map port names declared in [Ports] of [External Model] The file of subcircuit listed in [Corner] of [External Model] must be manually included in netlist if the subcircuit is used by external model Keywords para_begin and para_end are used to assign values to parameters which are declared in [External Model] with Verilog-A language 47

936- Multi-Lingual Model Support (2/2) This is an Instructor Guide page! Switch to "Notes" view.

946- Example bspice Dri Out Vcc 0 Ven Rcv + file= 'extmdlva.ibs' + model= 'vatest' + nd_in=PlsV + nd_en=Vcc + nd_outofin=Oti + typ = typ + power=off.ibs file(extmdlva.ibs) example ; [External Model] Language Verilog-A(MS) ; 48

956- Example This is an Instructor Guide page! Switch to "Notes" view.

966- Component Calls for [External Circuit] Support component calls for SPICE or Verilog-A formatted [External Circuit] [External Circuit] is used to describe either buffer (similar to [External Model]) or interconnection inside component The naming rule to probe a die node declared in Port_map of [Circuit Call] in a interconnection description: ‘cname’_’die_node_name’ 49

976- Component Calls for [External Circuit] This is an Instructor Guide page! Switch to "Notes" view.

986- Name Limit Extension The limit on IBIS filenames has been extended to 44 characters from the existing 24 characters The model and signal name limit has been extended to 40 characters from the existing 20 characters 50

996- Name Limit Extension This is an Instructor Guide page! Switch to "Notes" view.

1006- Lab 6: IBIS Buffers During this lab, you will use IBIS buffers and a transmission line to do a simple signal integrity analysis. IBIS buffers Transmission line Signal Integrity analysis 45 minutes 51

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