Jae Wook Lee

SIC R&D Lab.

LG Electronics

Contents

• Introduction

• Why power validation on mobile application processor? • Then, what to validate? Who is in charge of validation?

• Power Validation • Components of power • Lower power techniques and validation challenge • Type of power debugging • Why leakage power became so important? • Scenario power • Low power validation essentials • Correlation effort • High volume manufacturing

• Summary

Why are we validating power on mobile AP?

[Source: http://www.embedded.com/design/mcus-processors-and-socs]

Heat Sink, Cooling Fan

Cooling fan inside a mobile phone? Maximum power consumption on a mobile phone < several watts

[Source: http://anandtech.com]

Why are we validating power on mobile AP?

Skin surface temperature while using a mobile phone

[Source: http://www.eetimes.com/document.asp?doc_id=1279666] [Source: http://thebestsmartphones.org/iphone/the-iphone-5-review/]

Users want longer battery life !

Then, what to validate?

Various low power techniques are used when mobile AP are developed.

[Source: http://www.synopsys.com/Company/Publications/SynopsysInsight/Pages/Art4-low-power-IssQ2-12.aspx]

Who is in charge of validation?

Previously, one person, but now a team is needed with a good collaboration.

[Source: http://www.synopsys.com/Company/Publications/SynopsysInsight/Pages/Art4-low-power-IssQ2-12.aspx]

Components of power

Power = Static Power + Dynamic Power (+Short Circuit Power)

[Source: http://electronicdesign.com/power/understanding-low-power-ic-design-techniques]

Major leakage components

- Gate tunneling leakage - Sub-threshold leakage - Junction leakage

Dynamic power

- Charging/discharging Short circuit power - Shoot-through power

So, expecting simple validation?

Low-power techniques and validation challenge

[Source: http://soccentral.com/results.asp?CatID=488&EntryID=25950]

[Source: http://low-powerdesign.com/article_mentor_NarayananJilla.htm]

[Source: http://www.tela-inc.com/products/power-

optimization/leakage-speed-tradeoffs/]

Multi-Vt optimization Leakage power

MCMM Scenario power, Dynamic power

PG, DVFS Scenario power, DVFS, Minimum Vdd

Low Vdd Standby Power management, PG

[Source: http://www.pcworld.com/article/2010642/meet-clover-trail-

intels-chip-for-mid-range-windows-8-tablets-and-hybrids.html]

Type of power debugging

Leakage power validation Block (CPU, GPU, ISP, PLL, SRAM, etc.) Power-gating efficiency SoC

Dynamic power validation In-house power-virus Industrial standard power-virus: i.e. Dhrystone Benchmark tests

DVFS (Dynamic Voltage and Frequency Scaling) validation Adaptive/Dynamic voltage scaling considering process variation

Scenario power validation including idle/stand-by power validation

IR-drop/PMIC-droop validation Low-power validation, power-management validation, etc.

Why leakage power becomes so important?

We cannot disregard leakage power any more !

[Source: http://www.eetimes.com/]

Leakage current has a strong dependency on Voltage Temperature Process

Leakage power while enjoying a game? Voltage condition in

DVFS scheme?

Necessitates power-gating with multiple power domains low leakage cells for non-critical paths good power-management in both AP and S/W

Why leakage power becomes so important?

Leakage current is a good indicator of process along with Vth in power and performance optimization process tuning improving yield or reducing test cost

Performance (1/Vth)

Leakage

(in log scale)

Target

Target Target

Target

Target

Target

Target

Target

Target

Target

Type of power debugging – DVFS/DVS/AVS

[Source: http://www.cadence.com/Community/blogs/lp/archive/2010/08/24/dynamic-power-management-closed-loop-voltage-scaling.aspx]

[Source: http://www.eetimes.com/document.asp?doc_id=1202563]

Open-loop scaling requires statistical silicon data

using a tester safe margin from coarse

granularity

Closed-loop scaling validating HPM better optimization

Scenario power validation

3G Talk, Web browsing, Camera burst-shot, Idle, 1080p playing, etc.

Usage Case 1

Usage Case 2

Usage Case 3

Usage Case 4

Usage Case 5

Usage Case 6

Po

wer

Low power validation essentials

Debugging tools/environment

[Source: http://www.extremetech.com/extreme/166413-post-post-

pc-the-new-materials-tech-and-cpu-designs-that-will-revive-

overclocking-and-enthusiast-computing]

[Source: http://www.semiwiki.com/forum/content/405-moore%92s-law-semiconductor-

design-manufacturing.html]

Statistical analysis

Thermal control

Understanding DFT, clock network, and power management

Measurement technique

Correlation effort

Correlation among three parties are essential in early validation stage Degree of confidence Various benchmarks and usage scenario vs. volume data

[Source: http://www1.verigy.com/ate] [Source: http://www.logicbricks.com]

Design Kit/Platform board Production Tester/ATE

Power Management/Power Estimation

High volume manufacturing

[Source: http://anandtech.com/show/5365/intels-medfield-atom-z2460-arrive-for-smartphones]

How to guarantee the power consumption of each AP? Killing/Screening parts: When? Yield? Proper test contents with good correlation Volume data analysis Dynamic Voltage and Frequency Scaling support Test hole/escape between HVM and system board test Test time is also important !

Summary

Validating power in mobile AP becomes important, especially leakage power Validating low-power features/techniques and MMMC (Multi-mode multi-corner) is always challenging Analog value, not pass/fail: many of iterations Statistical analysis for better judgment become essential Improving power estimation accuracy/confidence in defining a new project