benefits and constraints of smps integration in...

November 24, 2008

D. ChesneauF. Hasbani

Benefits and Constraints of SMPS Integration in Wireless Multi Media Terminals

Power SoC 08

November 24, 2008 2

November 24, 2008 3

Introduction: Mobile Terminal Typical Content

November 24, 2008 4

How to achieveHigh EfficiencyLow VolumeLow Cost

How to achieveHigh EfficiencyLow VolumeLow Cost

Introduction: The Problem

More and more functions in mobile terminalsNeed massive integrationPower consumption increases drasticallyBut users still request large autonomy

More and more functions in mobile terminalsNeed massive integrationPower consumption increases drasticallyBut users still request large autonomy

November 24, 2008 5

Introduction

SMPS for Digital Base Band and MemoriesRequirements / CompatibilityConstraintsPossible Solutions

SMPS for Audio and Low Power RF functions

SMPS for RF Power Amplifier

Conclusion

I

II

III

Outline

November 24, 2008 6

Companion chip of DBB Complex ICMany IOs (200 to 300)Low Cost CMOS (5V compliant)

BGA package

5 to 6SMPS5 to 6SMPS

8 to 10LDOs

8 to 10LDOs

BatteryChargerBatteryCharger

AUDIOCODECAUDIOCODEC

AUDIOAMPs

AUDIOAMPs

GPADCGP

ADCClockGen

ClockGen

StateMachineState

Machine

DIGITALIF

DIGITALIF

I.0: Power Management Units Context

November 24, 2008 7

( )2mmmWMHz•

High EfficiencyPower Supply


I.1: SMPS for DBB Requirements

November 24, 2008 8

At light and medium loads

Low quiescent currentLow switching losses Low AC losses in coil magnetic core

At light and medium loads

Low quiescent currentLow switching losses Low AC losses in coil magnetic core

At heavy loads: Low ohmic losses

In Power Transistors Low RDSONIn Package Low parasitic resistanceIn power coil Low DC resistance

At heavy loads: Low ohmic losses

In Power Transistors Low RDSONIn Package Low parasitic resistanceIn power coil Low DC resistance

I.1: SMPS for DBB RequirementsHigh Efficiency Power Supply

November 24, 2008 9

( )2mmmWMHz•



DC & TransientAccuracy



November 24, 2008 10

Better DC & Transient accuracy helps toReduce static voltage & keep higher min voltageReduce bufferingReduce silicon areaReduce routing capacitanceAchieve more MHz for less mW and less area

Better DC & Transient accuracy helps toReduce static voltage & keep higher min voltageReduce bufferingReduce silicon areaReduce routing capacitanceAchieve more MHz for less mW and less area

DC Spread

mV for MHz!!!

I.1: SMPS for DBB RequirementsDC & Transient Accuracy

Load TransientResponse


( )2mmmWMHz•





Smallest PassiveComponents footprint




Must reduce L value and increase f

Must reduce C value

Coil Resistance versus frequency

0.01

0.1

1

10

10 100 1000 10000

F (kHz)

R ( Ω

)

3.0x3.0x1.02.5x2.0x0.82.0x2.0x1.02.0x1.2x1.0

Saturation Current versus Coil Values

0

1

2

3

4

0 2 4 6 8 10

L values (μH)

Sat

urat

ion

Cur

rent

(A)

4.0x4.0x1.84.0x4.0x1.23.0x3.0x1.02.0x2.0x1.42.0x2.0x1.0

0402 0603 0805

4.7µF

10µF

22µFC

Package size

…but not too much!!!

…but not too much!!!

I.1: SMPS for DBB RequirementsSmallest Passive Components Footprint








( )2mmmWMHz•

L Good Load C

Bad Load

f Switching Losses

f Coil RAC

L Coil RDC

Fast Loop High Quiescent Current

I.1: SMPS for DBB RequirementsCompatibility


( )2mmmWMHz•

High Current (>1A)

High Volume Coil

High Thermal DissipationHigh Bonding Inductance

Low Cost CMOS

Reliability vs

overshoots

5 to 6 SMPSBGA Package

I.2: SMPS for DBB Constraints


Select a low cost processSelect a package with low parasitic inductanceSelect a mid range frequency and coil value

And …

Select a low cost processSelect a package with low parasitic inductanceSelect a mid range frequency and coil value

And …

I.3: Possible integration solutions

Keep External components outside…Or

Split Power Management in 2, 3,… power modules2/3 Coil4/6 Capacitors

Keep External components outside…Or

Split Power Management in 2, 3,… power modules2/3 Coil4/6 Capacitors


Outline

Introduction

SMPS for Digital Base Band and Memories

SMPS for Audio and Low Power RF functionsRequirements / CompatibilityConstraintsPossible Solutions


Conclusion

I

II

III


Audio functionsInside PMUsorIn stand alone ASSP

< 50 IOS BGA or WLCSP

Low cost CMOS (0.13µm – 5V Compliant)

Audio functionsInside PMUsorIn stand alone ASSP

< 50 IOS BGA or WLCSP

Low cost CMOS (0.13µm – 5V Compliant)

II.0: Audio & Low Power RF Context

Low Power RF functionsIn dedicated RF chips0.65µm CMOS process WLCSP

Low Power RF functionsIn dedicated RF chips0.65µm CMOS process WLCSP






Low NoiseLow RippleLow NoiseLow Ripple

( )2mmmWSNR•

I.1: Audio and Low Power RF Requirements


Low NoiseFixed frequency Compatible with Audio or RF constraints

Low NoiseFixed frequency Compatible with Audio or RF constraints

I.1: Audio and Low Power RF Requirements Low Noise / Low Ripple

Low RippleRelatively high coil valueRelatively high capacitor valueMedium Switching frequency

Low RippleRelatively high coil valueRelatively high capacitor valueMedium Switching frequency






Low NoiseLow RippleLow NoiseLow Ripple

( )2mmmWSNR•

L Bad for C

Bad for

f Switching Losses

f Coil RAC

L Coil RDC

I.1: Audio and Low Power RF Requirements Compatibility


( )2mmmWMHz•

Low Current (<200mA)

Low Volume Coil

Low Thermal DissipationWLCSP Package

Low Inductance

Low Cost CMOS

Reliability vs

overshoots

1 to 2 SMPS

II.2: SMPS for Audio and Low Power Constraints


Low current requirementOK for coil volumeOK for WLCSPOK for medium frequency

Low current requirementOK for coil volumeOK for WLCSPOK for medium frequency

II.3: Possible integration solutions

Possibility to build modules with Stand alone ASSPMay be also with PMUs (1 coil)

Possibility to build modules with Stand alone ASSPMay be also with PMUs (1 coil)


Outline

Introduction



SMPS for RF Power AmplifierRequirements / CompatibilityConstraintsPossible Solutions

Conclusion

I

II

III


Power supply of an Envelope Reconstruction RF PA

EER- The PA operates in saturation- The SMPS provides the envelope signal- The full RF signal reconstructs at the output

RF

Env.

IQ

Mixer

RF-PA

SMPS

RF out


SMPS in the signal path

From Analog … … to SMPS specification

Large signal rate Output filter cutoff freq.

Spurious & Noise Fixed freq, output filter mask

Stability Load modeling

Signal AC BW Switching frequency

Linearity large BW close loop control

Low Z_out over full BW Low Z_in over full BW


SMPS accuracy : WCDMA envelope tracking

Symbol rate : 3.84MHzPeak output power : 2.2WV battery : 3.6VPAPR : 3.5dB


Spurs filtering

-70

-60

-50

-40

-30

-20

-10

0

10

20

1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200Frequency (MHz)

Pow

er (d

Bm

)

60dB


Convergent technology requirements

RF PA driver stage : high-voltage bipolar (high Gm) output stage : NLDEMOS (gain @ large I, high voltage tolerance, no thermal runaway, efficiency)

SMPSPower switches : NLDEMOS (low Ron, low Cgate)Controller : bipolar (high Gm)

Integration on a single chip!


Implementation example in ST BiCMOS 0.25

[V.Pinon et al., ISSCC’08]


SMPS test resultsMax Out power @ 3.6V battery 2W

Peak efficiency @ 3.6V battery 83% @2W

AC BW 15MHz

Fs 130MHz

Area (with pads) 0.5 mm2

2.9V – 4.3VBattery range

-39/-47dBcACLR 1/2

-60dBcPeak switching noise

1.95GHz WCDMA EER chip test results46% @ 27dBm RF out powerChip efficiency

1.1mm2Chip area


Measured efficiencies vs. output power

01020304050607080

5 10 15 20 25 30Pout (dBm)

PAE

(%)

RF-PA

SMPS

ER chip


ST BiCMOS 0.25 die

powerswitches

driverscontrol

driver

power

stagematching

biasbandgap

1mm

1.1mm

SMPS

RF PA


Outline

Introduction




Conclusion

I

II

III


For DBB: Integration in PMUs is difficult

High number of coils (5 to 6)High current / High Power dissipationProcess and Package versus high frequency

For DBB: Integration in PMUs is difficult

High number of coils (5 to 6)High current / High Power dissipationProcess and Package versus high frequency

Conclusion

Possible solution with new partitioningSolve passive components congestionSolve power dissipation issueIs it cost competitive ? (multiple packages)

Possible solution with new partitioningSolve passive components congestionSolve power dissipation issueIs it cost competitive ? (multiple packages)

Analog solution still the most cost effective?


For Audio and Low Power RF:Good Candidates for integration

Can be outside of PMUsLess Ios than PMUs = WLCSP1 to 2 coils requiredMedium current (200mA)Do not require very high frequency

For Audio and Low Power RF:Good Candidates for integration

Can be outside of PMUsLess Ios than PMUs = WLCSP1 to 2 coils requiredMedium current (200mA)Do not require very high frequency

Conclusion

Mixed mode architecture for time to market


Conclusion

For RF PA A real need for high frequency SMPS

Saves a lot of power in a EER systemSaves coil area on PCB…… and goes towards full integration

SMPS + PA common integrationSMPS and RF PA technology requirements are totally compatibleGives a new degree of freedom for platform partitioning

For RF PA A real need for high frequency SMPS

Saves a lot of power in a EER systemSaves coil area on PCB…… and goes towards full integration

SMPS + PA common integrationSMPS and RF PA technology requirements are totally compatibleGives a new degree of freedom for platform partitioning


Saturation Current versus Coil Values

0

1

2

3

4

0 2 4 6 8 10

L values (μH)

Sat

urat

ion

Cur

rent

(A)

4.0x4.0x1.84.0x4.0x1.23.0x3.0x1.02.0x2.0x1.42.0x2.0x1.0

(Data from Coilcraft LPS series)


Coil Resistance versus frequency

0.01

0.1

1

10

10 100 1000 10000

f (kHz)

R ( Ω

)

3.0x3.0x1.02.5x2.0x0.82.0x2.0x1.02.0x1.2x1.0

(Data from Coilcraft, TDK, Toko)

benefits and constraints of smps integration in...

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