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Copyright © 2012 MIPI Alliance. All rights reserved.
Jeremy Hendy Nujira
Copyright © 2012 MIPI Alliance. All rights reserved.
Coolteq.L Single-Chip Envelope Tracking Supply Modulator
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Copyright © 2012 MIPI Alliance. All rights reserved.
Legal Disclaimer
The material contained herein is not a license, either expressly or impliedly, to any IPR owned or controlled by any of the authors or developers of this
material or MIPI. The material contained herein is provided on an “AS IS” basis and to the maximum extent permitted by applicable law, this material is
provided AS IS AND WITH ALL FAULTS, and the authors and developers of this material and MIPI hereby disclaim all other warranties and conditions,
either express, implied or statutory, including, but not limited to, any (if any) implied warranties, duties or conditions of merchantability, of fitness for a
particular purpose, of accuracy or completeness of responses, of results, of workmanlike effort, of lack of viruses, and of lack of negligence. ALSO,
THERE IS NO WARRANTY OR CONDITION OF TITLE, QUIET ENJOYMENT, QUIET POSSESSION, CORRESPONDENCE TO DESCRIPTION OR
NON-INFRINGEMENT WITH REGARD TO THIS MATERIAL.
All materials contained herein are protected by copyright laws, and may not be reproduced, republished, distributed, transmitted, displayed, broadcast or
otherwise exploited in any manner without the express prior written permission of MIPI Alliance. MIPI, MIPI Alliance and the dotted rainbow arch and all
related trademarks, tradenames, and other intellectual property are the exclusive property of MIPI Alliance and cannot be used without its express prior
written permission.
IN NO EVENT WILL ANY AUTHOR OR DEVELOPER OF THIS MATERIAL OR MIPI BE LIABLE TO ANY OTHER PARTY FOR THE COST OF
PROCURING SUBSTITUTE GOODS OR SERVICES, LOST PROFITS, LOSS OF USE, LOSS OF DATA, OR ANY INCIDENTAL, CONSEQUENTIAL,
DIRECT, INDIRECT, OR SPECIAL DAMAGES WHETHER UNDER CONTRACT, TORT, WARRANTY, OR OTHERWISE, ARISING IN ANY WAY OUT
OF THIS OR ANY OTHER AGREEMENT RELATING TO THIS MATERIAL, WHETHER OR NOT SUCH PARTY HAD ADVANCE NOTICE OF THE
POSSIBILITY OF SUCH DAMAGES.
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Copyright © 2012 MIPI Alliance. All rights reserved.
Nujira Company overview
• Fabless IC vendor
• World leader in Envelope Tracking
• The only technology for broadband, high efficiency PAs
• >250 man-years investment in High Accuracy Tracking™
• Coolteq™ products cover power levels from <1W to 10kW+
• 133 patents granted & pending • Most extensive ET patent portfolio in the industry
• Headquartered in Cambridge, UK
• Design Centres in Edinburgh and Bath, UK
• Founder member of OpenET Alliance
• Active participant in new MIPI ACI WG • Analog Control Interface – Envelope Tracking subgroup
• Standardising physical interface between chips
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Copyright © 2012 MIPI Alliance. All rights reserved.
Envelope Tracking – an overview
Supply
Voltage
Transmitted
Dissipated
as Heat
Fixed
Supply
Voltage
Dissipated
as Heat
Transmitted
Conventional PA
Power
Amplifier
Baseband /
RF up converter
DC/DC
Converter
Power
Amplifier
Baseband /
RF Up converter
Envelope signal
Envelope Tracking PA
ET
Power
Supply
Planned standard from MIPI ACI Working Group
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Copyright © 2012 MIPI Alliance. All rights reserved.
Envelope Tracking vs Average Power Tracking
Direct battery connection • Simple, but poor efficiency
• Efficiency is strong function of waveform PAPR
• LTE dissipation ~2x W-CDMA
3GPP power
control slot time
0.5 ms / 1 ms
Average Power Tracking (APT) DC:DC
• Per-slot tracking based on TX power control level
• Improves efficiency at low power
• Doesn’t help at high power
• Same waveform dependence
Envelope Tracking • Dynamic, high bandwidth supply
tracking of signal amplitude
• Improves efficiency in top 90% of TX power control range
• Waveform-independent; LTE dissipation ~1.2x W-CDMA
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Copyright © 2012 MIPI Alliance. All rights reserved.
RF PA becoming the dominant consumer of power in handsets
• LTE data = 10x 3G voice
• Less than 1 day between recharges
• More than 3W • Gets hot!
• Challenging
thermal design
• High peak currents
0 mW
500 mW
1000 mW
1500 mW
2000 mW
2500 mW
3000 mW
3500 mW
4000 mW
W-CDMA voice0 dBm
HSUPA 15 dBm
LTE23 dBm
RF PA
Transceiver
Modem
WiFi/BT/GPS
Audio
Apps Processor
Screen & backlight
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Copyright © 2012 MIPI Alliance. All rights reserved.
LTE PA spending significant time at maximum power
• Short bursts of TX data at max power
• Highest spectral efficiency
• PA spends >50% of its time at maximum power
Data source: Signals Research Group, Signals Ahead report Volume 6, No. 11, Oct 7, 2010 (www.signalsresearch.com)
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Copyright © 2012 MIPI Alliance. All rights reserved.
60x increase in RF PA energy consumption from 3G to LTE
Multiband LTE1800 mW
LTE data1600 mWHSUPA data
250 mW
3G voice26 mW
0
1
2
3
4
5
6
7
8
9
10
0.1 1 10 100 1000
Wav
efo
rm P
eak
-to
-Ave
rage
Po
we
r R
atio
, dB
Average Handset transmit power control level, mW
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Copyright © 2012 MIPI Alliance. All rights reserved.
0 mW
500 mW
1000 mW
1500 mW
2000 mW
2500 mW
DC:DC converter
Coolteq ET modulator
PA dissipation (DC:DC)
PA dissipation (Coolteq)
RF front end losses
Transmitted RF (200 mW)
3G
(W-CDMA)
3.5G
(HSUPA)
4G
(LTE)
40%
saving
45%
saving
55%
saving
Measurements of
commercial PA device
at 23 dBm transmitted
RF power, comparing
traditional DC:DC converter
and Coolteq.L Envelope
Tracking
Envelope Tracking power savings
Coolteq enables 4G transmissions using less power than today’s 3G PAs
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Copyright © 2012 MIPI Alliance. All rights reserved.
>50% reduction in PA heat dissipation simplifies thermal design
Fixed supply voltage Envelope Tracking
Average Output Power 27.3 dBm
Dissipated Power (device) 1180 mW
Measured Case Temperature 62.9 ºC
Output Power 27.3 dBm
Dissipated Power (device) 487 mW
Measured Case Temperature 45.3 ºC
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Copyright © 2012 MIPI Alliance. All rights reserved.
ET enables multiband PAs which ues less power than today’s 3G PAs
3 broadband ET PAs cover 700 MHz – 2.7 GHz
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Copyright © 2012 MIPI Alliance. All rights reserved.
System Block Diagram
Page
12
© 2011 OpenET
Alliance Ltd
Power Amplifier Q-DAC
I-DAC
DAC
Magnitude
calculator
RF drive
gain
matching
Shaping
table Post-envelope
gain & offset
Delay
Balancing
Envelope
Tracking
Modulator
To
Antenna To
Rxr
Duplexer
A
B C Transmit System
• Digital logic overhead: ~50K gates in transceiver
• Fast DAC needed– similar spec to I/Q DACs
• Envelope Interface A – differential analogue interface
• Specified by OpenET Alliance; also being worked on in MIPI ACI
MIPI RFFE Control Interface
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Copyright © 2012 MIPI Alliance. All rights reserved.
PA efficiency and gain vary with supply voltage
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Copyright © 2012 MIPI Alliance. All rights reserved.
Under ET, a digital LUT controls the “shape” of the supply voltage
More gain
Higher Efficiency
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Copyright © 2012 MIPI Alliance. All rights reserved.
Nujira’s patented ISOGAIN™ ET linearizes the PA without requiring DPD
• Result: 6-10 dB ACLR improvement
• 2-3 dB more “linear power”
• Deliver full power LTE to the antenna
Fixed supply
Envelope Tracking
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Copyright © 2012 MIPI Alliance. All rights reserved.
ET delivers more power and cleaner signals, even into an antenna mismatch
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Copyright © 2012 MIPI Alliance. All rights reserved.
So what’s so difficult about Envelope Tracking?
• High power supply bandwidth requirement
• 30-60 MHz for 20 MHz LTE
• Very high slew rates
• Low noise power supply
• ACLR spec is “easy” to hit
• RX-band noise (self desens) much harder
• High efficiency ET supply modulator
• Needs ~80% power conversion efficiency
• ET<>PA supply feed is critical
• ET chip replaces decoupling capacitor
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Copyright © 2012 MIPI Alliance. All rights reserved.
Envelope Tracking ecosystem status
• 12 of 14 platform chipset vendors are committed
to include an Envelope Tracking interface
• 4 with silicon now
• 4 in silicon design phase
• 4 at specification / architecture phase
• All PA vendors have an active ETPA program
• First stage: “ET Capable” PAs available now
• Next step: “ET Optimised” PAs starting to show up
• MIPI ACI working on interoperability standard
• Expect ET-enabled reference platforms 2H2012
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Copyright © 2012 MIPI Alliance. All rights reserved.
Coolteq.L Envelope Tracking chip for smartphones & terminals
• Single chip ET supply modulator
• 0.18u CMOS process
• Replaces DC:DC converter to supply the RF PA
• Supports 20 MHz LTE bandwidths
• Includes ET and APT operating modes
• MIPI RFFE V1 control interface
• OpenET analogue differential Envelope interface
Smartphone
Chipset
PA RF
Envelope
MIPI RFFE
Control
Battery
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Copyright © 2012 MIPI Alliance. All rights reserved.
Thank you – Questions?