Company Confidential | 2009 Micron Technology, Inc. | 1 Micron Contact: Tim Hollis February 16 University of Utah Senior Clinic Company Confidential | 2009 Micron Technology, Inc. | 2 High-level Summary of the Proposed Project Investigate the accuracy of the so-called 2-phase or 2- pass power supply noise analysis methodology. Identify limitations in the algorithm and recommend constraints which can be applied to limit sensitivity to any inherent error. When is the analysis valid and when should a more comprehensive analysis be applied? Provide recommendations for enhancing the accuracy of the methodology. Company Confidential | 2009 Micron Technology, Inc. | 3 Background Power delivery is quickly becoming more and more complicated Company Confidential | 2009 Micron Technology, Inc. | 4 Background As integrated circuit (IC) operating frequencies and signaling datarates continue to increase: 1. The characteristics of the power delivery network (PDN) appear less and less ideal. 2. The non-idealities of the PDN become more problematic, because there is less voltage and/or timing margin to work with. R PBus Vcc Gnd C Die Vcc Gnd C DIMM C MthrBrd L DIMM L MthrBrd L DIMM L MthrBrd L Package Vcc CKT Gnd CKT = Vcc CKT = Gnd CKT Company Confidential | 2009 Micron Technology, Inc. | 5 Impact of PDN Non-idealities Same Data Pattern Company Confidential | 2009 Micron Technology, Inc. | 6 Off-Chip Power Delivery The impedance of the off-chip power delivery incorporates a combination of inductive, capacitive, and resistive effects. Even when the PDN impedance is very low (fraction of an Ohm), the large high-frequency currents drawn by todays ICs can induce large voltage variation across the PDN. Company Confidential | 2009 Micron Technology, Inc. | 7 GDDR4 (Graphics DRAM) Supply Noise 327mVpp 383mVpp Bottom of Package showing Ball Grid Array (BGA) Vdd Vss On-Chip Power Delivery Every circuit mapped to a corresponding x-y Pbus coordinate Company Confidential | 2009 Micron Technology, Inc. | 9 On-Chip Power Delivery February 16 PKG VCCQ VSSQ VCC GND PKG VCC VCCQ VSSQ GND PKG VCC VCCQ VSSQ GND Company Confidential | 2009 Micron Technology, Inc. | 10 Simulation Time vs. Model Complexity Ideal PDN + PowerBus + Package + ArrayCurrentCombine Package And PowerBus Combine Package, PowerBus, and ArrayCurrent Combine Package, PowerBus, ArrayCurrent, and LogicNoise Company Confidential | 2009 Micron Technology, Inc. | 11 Measurement Accuracy Essentially, all models are wrong, but some are useful George E. P. Box (Professor Emeritus of Statistics at the University of Wisconsin) Company Confidential | 2009 Micron Technology, Inc. | 12 2-Phase (or 2-pass) Supply Noise Analysis Vcc Gnd Vcc Gnd I Ckt Vcc Gnd I Ckt +V-+V- +V-+V- Phase 1: Run time-domain simulation with all circuitry in place and capture circuit-specific currents into and out of the supplies Phase 2: Apply extracted currents to full Power Delivery Network and capture static and dynamic voltage changes Z PDN Company Confidential | 2009 Micron Technology, Inc. | 13 2/12/20162008 Apache Design Solutions Industry Example 1 Apaches T otem, CPM, and Redhawk Tools Static and Dynamic IR/EM Maps Power nets Ground nets Taken from Early Analysis Using RH/Totem: Prototyping, Early CPM Creation and Co-design, Apache Design Solutions, 2008 Company Confidential | 2009 Micron Technology, Inc. | 14 Voltagestorm Power and Power Rail Verification, Cadence Design Systems, Inc. Online Datasheet Industry Example 2 Cadences VoltageStorm Company Confidential | 2009 Micron Technology, Inc. | 15 A recent presentation from Hynix Semiconductor shows the output of a tool applying the 2-phase analysis method J. Lee, Chip-level Power Integrity: Trend and Challenge for On-chip PDN Design, online:Industry Example 3 Images from Hynix Power Delivery Presentation Company Confidential | 2009 Micron Technology, Inc. | 16 Industry Example 4 Synopsys Power Net Reliability Analysis Tool Page taken from Synopsys HSIM Plus Reference Manual Summarizes 2-phase Method applied by PWRA (Power Net Reliability Analysis) tool Part of the HSIM Plus Suite Company Confidential | 2009 Micron Technology, Inc. | 17 Some Issues with 2-Phase Analysis Analysis runs Open-loop, whereas in reality, the circuits respond to supply variation (there is feedback) Current depends on V DS Vcc Gnd I Ckt Vcc Gnd I Ckt Gnd I PU I PD Vcc VCC and GND currents arent the same, implying the need for 2 current sources, but can they be connected in series? Nonlinear Effects Company Confidential | 2009 Micron Technology, Inc. | 18 Suggestions for Investigation General Questions: What is the error associated with an open-loop methodology? Are certain circuits more sensitive to the error (nonlinear circuits, noise-sensitive circuits, etc.)? Can this method be used to verify circuit timing? Does the method apply more accurately to certain power domains? For example, Input/Output domains where current also flows in and out of the signal path or Internal Logic domains where nearly all current flows directly from one supply to the other. What about circuits on the domain boundary? Implementation Questions: What about multi-phase analysis, rather than just two phases? Capture currents, Capture supply voltages, Recapture currents,... How should the two current sources (pull-up and pull-down) be combined, or can they? How does capturing the initial currents with the Decoupling Capacitance in place effect the accuracy? Company Confidential | 2009 Micron Technology, Inc. | 19 Deliverables Lets publish a paper! Publishing will require three things: Background: The team will need to gather details from additional references. Rigor: Quantitative data on Voltage and Timing Error versus Simulation Time and Memory Requirements. Contribution: Proposals for how to improve on the methodology or how to replace it completely. Deliverable = Publication-ready Paper Company Confidential | 2009 Micron Technology, Inc. | 20 Resources Tim Hollis Micron Technology, Inc. Fuad Badrieh Micron Technology, Inc. Eric Booth Micron Technology, Inc. Louis Do Apache Design Solutions (tentative collaboration with Apache) February 16