Wireless Low Power and Verification Challenges

TM

Freescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Wireless Low Power and Verification Challenges

Presented toDVClub, Austin, Tx

Nov 20, 2006

.Milind Padhye, Noah Bamford, Ken AlbinFreescale Semiconductor Inc.

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TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Wireless Carriers

Low Power Design is business critical need and has a direct impact to carrier revenue.

If the cell phone is powered off, The source of revenue is off for carrier.

Performance needed to sell the phone. Power needed to bring revenues.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Wireless and Handheld Devices

►Standby & Talk time - Benchmark parameters in cell phone industry.►Music playback time - Benchmark for MP3 capable phones.►Frequent battery charging - Major negative in consumer mind.►Increase performance with large battery – Increased Cost►Increased Heat in phone – Increased liability and TCO.

Power Performance ratio must be very high to win consumer mind.

• End Consumers are becoming power aware and can make intelligent decisions and smart choices on power.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Trends - GSM Phone Current

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TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Leakage Current in 65nm, Major concern for Wireless Design

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Energy

It’s about Energy

• Battery life is proportional to energy consumed

• Energy is power consumed over time

• Wireless designers must manage energy

consumption.

Goal: Extend Phone Battery Life

To extend battery life, designers must minimize active and leakage power.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Problem Focus View

Design Intent Hardware support for power gating, low-power idle modes, SRPG, AWB, DVFS, DPTC, Biasing techniques at all levels.

Design Verification

Behavioral and RTL verification, Gate level verification, testbench styles, static and dynamic power Rule checking.

Low Power infrastructure

Support library infrastructure with special cells. New cells andparameters for cz. Multimode/multivoltage support infrastructure.

PROCESS node Definitions

Transistor design, Vt Optimization, memory bitcell design. custom and reusable analog. Silicon correlation.

RTL2gds, Power Integrity, Multimode synthesis, Placement, power grid creation, analysis, power estimation

Design Implementation

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Low Power Design Needs

►Support Low Power Design Techniques thru the entire design flow using a single file format.

• Design RepresentationAccurately define and capture the low power design intent, modes and constraints.

• Design ImplementationFloorplan and power grids.Common constraints for all tools (Synthesis, APR, timing, DFT)Design analysis tools with single power constraints.Accurate power estimation and measurements

• Design VerificationVoltage oriented simulatorsVarious static power technique modeling and simulations.Silicon validation and correlation.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Static Power Design

►Static Power is crucial for defining standby time of cell phone.►Multiple Leakage Reduction Techniques

• Active Well Biasing (AWB)• State Retention Power Gating (SRPG)• Save and Restore with power gating. (S&R PG)• Multi-Vt based design styles• Aggressive Voltage Reduction during standby mode (RV)• Device biasing. • Switches, Isolation collars and level shifters.

►Static Power a big part of active power • Use switches for power mode switching. • Thermal dissipation issues in packaging.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Example Leakage Reduction Techniques

C65 Leakage Reduction Example

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TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Multi Voltage Design Styles - DVFS

►Voltage has quadratic effect on power.►In Multivoltage design Style

• Unused portion of design is switched off.• Low performance portion is running at lower voltage• High performance portion is at higher voltage.

►Voltage partitioning decisions are crucial and very key for power performance factor. ►Clocking is the major challenge for multivoltage designs. Need intelligent clock tree builders.►Asynchronous protocols to enable efficient voltage partitioning.►Design is optimized for multi voltage conditions.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Isolation and Percolation

►Picture power managed vs non power managed design implementation►When a module is powered off, outputs will float.►These outputs can corrupt the state of receiving modules.►Modules must be isolated ►A separate logic is inserted to isolate and percolate.► Logic State of isolation is important and can cause adverse effects if improper.

Module BModule A

VDD

Module BModule A

VDD

ISO

Controller

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Retention Verification

►A module can be turned off to save leakage.►The state of module B must be retained during power off.►Special circuits and flipflops have been created for this purpose.►Need to verify

• The state was saved correctly.• State restored correctly.• System can function after powerup.

►The controller must ensure the correct save and restore sequence.

Module BModule A

VDD

ISO

Controller

Module BIn

RetentionModule A

VDD

ISO

Controller

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Voltage and Frequency Variation

►Voltage of module A is reduced when lower performance need.►Change of voltage is associated to change of Clock.►Isolation is now Lisolator. (level Shifter & isolation)►Need to verify

• System performance state.• Prepare & communicate regarding

voltage change..• System operational during change.• System operational after change.

►The controller must ensure the correct operating sequence and monitor progress.

Module BIn

RetentionModule A

VDD

ISO

Controller

Module BIn

RetentionModule A

VDD

LISO

Controller VDDX

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

Power Architecture Verification

►Architectural analysis required to achieve efficient voltage partition.

►Global Power Controller• Partial or full power up and power down is a controlled sequence.• Verify the sequence control and state machine completely.• The Global Power Controller should be capable of capturing and

relinquishing the controls appropriately.

►The system should be functional and must be verified• During power off process• After power off has completed• Power up decision making• During power up• Full recovery after power-up.

►Ensure consistency of Power Programming Model in specification.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

How Does the world of Verification Change

►Verilog does not have a concept of power on/off.►Verilog does not have association of voltage levels.►Power shut off and multi voltage design style has brought in multiple new components in chip.►Gate level and circuit level simulations are expensive and timeconsuming and very late to fix the problems. ►Functional coverage of state of system at the time of power off and activities following power up should be gathered►All power related features must be checked at RTL stage.►Power Equivalency Checks needed between RTL & gate.►Power estimation in various functional mode needs to be integrated with power verification.

TMFreescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006.