Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION...

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CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15 Power Delivery Network (PDN) Analysis Edoardo Genovese

Transcript of Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION...

Page 1: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Power Delivery Network (PDN)

Analysis

Edoardo Genovese

Page 2: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Importance of PDN Design

Power

Deliver

Network

(PDN)

Ensure clean power

EMC Limit

Signal Integrity

Page 3: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Power Delivery Network (PDN)

Power net

Ref. net

PDN consists:

1. VRM (voltage regulator module)

2. Capacitors (Decoupling/Bypass)

3. PCB parasitic impedance

4. Active device (On Package Decap)

Bulk

caps

VRM MB

caps

Active

device

Page 4: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

IR-Drop

AC PI Analysis

Decap Analysis Tool

SSO from DDR2 Module

PCB+Pckg+Chip

Power Integrity Simulation

Courtesy of SIEMENS

Page 5: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Board Description

130mm

70mm

8 metal layers board with

total thickness 1.696mm

1.8V power plane to be

analyzed located in 4th

layer

1 memory controller and

2 DDR2 memory modules

Courtesy of SIEMENS

Page 6: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

IR-Drop Simulation 19 CPU pins, 16 Mem I pins & 16 Mem II pins

@ 20mA 1.8V

Component Voltage (V) VDD Drop

(V)

GND Drop

(V)

DC

Resistance

Memory

controller

Group

1.78849 10.507m 1.007m 575mOhm

Memory

Module I

Group

1.7889 10m 0.969m 498mOhm

Memory

Module II

Group

1.789 9.409m 0.929m 469mOhm

JEDEC 79-2F

Mem.

Ctrl

II I

Page 7: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

PDN Impedance of 1.8V Net

3 PDN Impedances are plotted

from three different components:

D1 the memory controller

D3 and D4 the memory modules

Page 8: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Spatial Impedance Plot

Impedance plot on P1V8 plane

seen from memory controller

@2.6GHz

Impedance plot on P1V8 plane

seen from memory module I

Impedance plot on P1V8 plane

seen from memory module II

Page 9: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

220pF

Decap Placement

Decaps shifts the high impedance

at its placement area

Page 10: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

SSO Analysis for 2 DQ lines

VRM

2 I/O

Buffer:

Driver

2 I/O

Buffer:

Input

DDR2-400 I/O Buffer IBIS

PRBS N=7

11010101101…

Page 11: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Transient Response

No Decaps With Decaps

Power Supply VDD

Page 12: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Over designing the PCB Additional BOM cost

slightly or without performance improvement

Decap Analysis Tool

Define the target impedance

Define the list of parts for

optimization

Start the optimization

Multiple goals:

Optimizing the BOM cost

Optimizing the PDN impedance

Page 13: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Decap Analysis Tool Optimization (Step 1)

Target Impedance

Part lib. of current

Decaps mounted on PCB

Page 14: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Decap Analysis Tool Optimization (Step 2)

Removing the decaps

from PCB (Bare board)

Page 15: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Decap Analysis Tool - Results Locate the marker to impedance curve manually and

optimizing the impedance

Initial config. with

23 decaps

Impedance curve

with 10 decaps

Before: 76¢

After : 52¢

Page 16: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Decap Analysis Tool – Results (II)

Run the automatic impedance optimization

Impedance curve

after optimization

Before: 76¢

After : 33¢

Page 17: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

PDN Impedance: PCB + I/O Buffer Pckg

PCB PACKAGE

VDD Line

VSS Line

+ - PDN Impedance Z VRM

Page 18: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

PDN Impedance Comparison

Series resistive

and inductance

from package

Page 19: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

PDN Impedance: PCB + Package + Chip

PCB PACKAGE

VDD Line

VSS Line

+ -

Total PDN

Impedance Z

VRM CHIP

SPICE

model

from Vendor

or

using “c_comp”

keyword from

I/O buffer IBIS

Page 20: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

PDN Impedance Comparison

Lumped RC DIE or

better SPICE

improve the high

frequency PDN Imp.

Page 21: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

SSO Analysis Setup

CHIP SPICE

model

RLC Package

Page 22: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

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Transient Response

Max Noise: 1.89V

Max Noise: 1.84V

PCB only PCB + Package + Chip

Page 23: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Impedance Measurement Method

Two port shunt-through measurement:

Measuring the ZDUT

connectionZconnectionZ

DUTZ

connectionZ

One port measurement:

Measuring the Zconnection + ZDUT

DUT

DUTconn

DUT

I

DUTconn

I

ZZZ

Z

I

V

I

VZ

ZZI

VZ

.2

2

02

112

.

01

111

1

2

Page 24: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Probing Position

GND pins

PWR pins

Goals:

Very small layout area

for probing (2mm²)

High frequency

measurement (up to 10GHz)

Page 25: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Comparison

Measurement of bareboard Measurement with mounted decaps

Page 26: Power Delivery Network (PDN) Analysis - CST · PDF fileCST – COMPUTER SIMULATION TECHNOLOGY | | Jun-15 Importance of PDN Design Power Deliver Network (PDN) Ensure clean power EMC

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jun-15

Conclusions

Frequency Domain Analysis

• Quick and less computational effort

• Optimization via Decap Tool analysis

• No charging effect

Time Domain Analysis

• Provides more realistic I/O behavior (using IBIS buffer)

• Higher simulation time for complex board HPC

Impedance Measurement

• One Port measurement

• Two port measurement