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Bob Giometti Vice President R&D and Engineering, SkyCross [email protected]

New Antennas for Mobile Technology

Presented at the Antenna Systems Conference December 12-13, 2013 Las Vegas, NV

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Contents

1. Introduction

2. LTE-A and the Mobile Device Antenna

3. LTE-A: Impact on the Antenna System a. Requirements

b. Carrier Aggregation c. Drivers for Antenna Tuning

4. Enabling Technologies a. Aperture Tuning b. Tunable Match Network c. Hybrid Approach d. Co-location of antennas e. Isolated Mode Antennas (iMAT) - Beam Forming Application

5. Summary

Introduction

- Over 20 years experience in the wireless industry

- Mobile phone product development at Motorola/Google

- Electrical design lead for the original RAZR

- BSEE/MSEE Illinois Institute of Technology

- Joined SkyCross as VP of R&D and Engineering Jan. 2013

Background/Bio

Presenter

Presentation Notes

Good morning everyone, my name is Bob Giometti and it’s an honor to be selected as the keynote presenter at Antenna Systems 2013. Today I will be presenting how advanced antenna technology is making an impact on mobile device communication services along with some of the challenges that lie ahead.

LTE- A and the Mobile Device Antenna

• Many bands (40+ and counting….) – 700 MHz in US (sub-bands for AT&T and Verizon) – AWS (2.1/1.7 GHz) in US – 790-862 MHz in Europe – 2.6 GHz FDD – mainly in Europe – 2.6 GHz TDD – China, Europe – 2.3 GHz TDD – China, Korea, India – 600MHz on the way!

• GPS, BT, FM, NFC,…

• WiFi (Dual Band)

• Tx Diversity

• MIMO 2x2, 3x3, 4x4,…

• Carrier Aggregation

– Low/Low, Low/High, High/High

LTE-A: Squeezing Even More Into The Mobile Device

Challenges facing today’s Mobile Device Antenna Engineer

Traditional antenna performance is inadequate to meet market demands for: Increasing number of frequency bands (4G/LTE ) Increased data traffic clogged networks Real life use cases (head, hand, slider phone ) Thinner phones Smaller antennas Quality of Service challenges

Bands of Interest vary by: Country / Region Network provider Protocol

Need for advanced adaptive antenna/RF solutions

“Advanced Smart Antennas” provide improved RF Performance & Increased Flexibility

LTE-A: Impact on the Antenna System

Enables more users, more applications, and a better experience

Source: Rysavy Research/4G Americas, 2012

LTE 2010 to 2012 •5 or 10 MHz Radio Channels •2X2 Multiple Input Multiple Output (MIMO)

LTE- A 2013 to 2016 Higher Capacity/Throughput and/or Efficiency

•Wider Radio Channels: 20 MHz •Carrier Aggregation: up to 100 MHz •Advanced Antenna Configurations •More Advanced MIMO (Higher Order, Multi-User, Higher Mobility) •Coordinated Multipoint Transmission •Het-nets (Microcells/Picocells/Femtocells)

• Easiest way to arrange aggregation: use contiguous component carriers within the same operating frequency band (as defined for LTE), so called intra-band contiguous.

• May not always be possible, due to frequency allocation scenarios.

• For non-contiguous allocation it could either be intra-band, i.e. the component carriers belong to the same operating frequency band, but are separated by a frequency gap, or it could be inter-band, in which case the component carriers belong to different operating frequency bands.

Carrier Aggregation Considerations

• LTE smartphones are challenged to achieve tightening carrier performance expectations – 4G LTE speeds/capacity require MIMO (multiple LTE antennas) – Growing number of operating frequency bands (number of antennas) – Aggressively styled device form-factors (constrained space)

• OEMs seeking new technical solutions to address challenges – Tunable antenna solutions seen as the desired approach – Progressive OEMs already initiating smartphone architectures that support

tunable antenna modules

• LTE-A Requirements – Carrier Aggregation – Higher Levels of MIMO – Tx Diversity

LTE-A Drivers for Antenna Tunability

Antenna Tuning Technologies

Tunable vs. Passive Antennas

• Integrates tuning elements, antenna, and interface

• Smaller size (smaller than

conventional passive antennas at same efficiency) or higher gain in same size to reduce Tx power consumption (increased battery life)

• Separate from and complementary to feed-point impedance matching

• Supports Carrier Aggregation requirements

• Primary/secondary antennas can

be co-located for greater space reduction

• Potential to simplify filter circuits • Simple 1 or 2 bit interface and

control

Motivation for Tunable Antennas 1. Greater band coverage +MIMO in accepted form factor allocated

space

2. Smaller Antenna: 1000 cubic millimeters or less (handset OEMs)(need more tuning states)

3. Head/Hand Effect mitigation (requires sensor and algorithm) (Operators)

4. Higher ASP stemming from integration of antenna and tuning elements/control (Antenna Suppliers)

5. Lower VSWR (PA Suppliers)

6. Reduced Filter Requirements (Filter suppliers)

Aperture Tuning • Integrates tuning element, antenna,

and interface

• Antenna resonance is changed directly by the tuning element.

• Allows antenna to be made smaller or cover more bands than with passive antenna

• Simple interface and control to achieve open loop coverage on a band-by-band basis

• Often used with tuning devices such as switches or DTCs for open or closed loop control.

• Can be thought of as a “coarse tuner”

Tunable Matching Network • Used to improve VSWR match to

antenna.

• Not considered as producing optimal radiation efficiency compared to Aperture Tuning

• Improves power coupled to antenna over frequency of operation and under varying usage or environmental conditions

• More complex interface generally with 6 or more bits of control

• Can use analog tuning devices such as BST and Varactor diodes, may be open or closed loop

• Can be thought of as a “fine tuner”

Aperture Tuning (AT) vs. Tunable Matching Network (TMN)

Efficiency Comparison Between Passive Broad Band and State-Tuned-Aperture Antennas

State 1 State 2 Broad Band

Low Bands High Bands

Significant improvement in low band performance

>2 dB

Minimal impact to high band performance

~0.8 dB

Hybrid Approach: Aperture + Match Tuning

RF (Port 1)

Microcontroller Control Algorithm

Flash Memory

RF (Port 2)

Tunable Matching Network (Fine Tuner)

Optimize Performance

Diversity Aperture Tuned Antenna (Coarse Tuner) Band Selection

MIPI RFFE GPIO Control

Tunable Matching Network (Fine Tuner)

Optimize Performance

Diversity Aperture Tuned Antenna (Coarse Tuner) Band Selection

Antenna Co-Location

Antenna Proximity Problem • Far apart

– Negligible coupling between antennas

– spatial separation makes antenna patterns unique

– How far: generally more than about half wavelength (17 cm at 900 MHz) – size not feasible for many consumer products

• Close together - coupling between antennas may

be a problem (RX saturation or desense, TX distortion)

- coupling hurts radiation efficiency as power goes into neighboring antenna and not to far field

- patterns lose uniqueness and are highly correlated (loss of MIMO capacity or loss of diversity gain)

- Reality of many consumer products

Antenna starts to couple more to its neighbor than to the far-field

The MIMO Antenna Solution for 4G

: Isolated Mode Antenna Technology

• iMAT is a patented technology that allows a single antenna structure to behave like multiple antennas through the use of multiple feed points.

• Each feed point accesses the single antenna as if it consisted of 2, 3, or more independent antennas that are highly isolated with superior link performance gain.

• This compact solution is applicable to any mobile device! iMAT supports legacy networks and is essential for next generation protocols that require diversity or MIMO.

Patented Technology

Enables Multiple Antennas in Small Spaces

Antenna Requirements • Diversity/MIMO • High isolation • High radiation efficiency • Low correlation coefficient • Small size

d

Conventional Smart Antenna

Approach

Isol

atio

n dB

0

-10

-20

-30 Frequency

60

50

40

30

Effi

cien

cy %

ISO

EFF

SkyCross iMAT Solution

Isol

atio

n dB

0

-10

-20

-30 Frequency

60

50

40

30

Effi

cien

cy %

ISO

EFF

1 2

The iMAT solution offers high efficiency, superior isolation, and low correlation coefficient while maintaining equivalent return loss, with a single antenna!

Technology Applications • WiFi and/or WiMAX • 4G/LTE • HSDPA / HSUPA • 1XEVDO • 802.11n, 802.11ac • Mobile video (CMMB, T-DMB,

DVB-H)

SkyCross Antenna Technology

Breakthrough!

1 3 . . . 3 . . .

d

2

iMAT: Far-Field Patterns

• Each resonance mode has a unique far field pattern • With iMAT approach each antenna port couples to a different

combination of the two fundamental modes • The resulting far-field patterns are also unique to each other

resulting in low ECC

Combination

- =

+ =

Pattern phase reversal

Farfield pattern from Port 1

Farfield pattern from Port 2

Common Mode

Differential Mode

iMAT: Concurrency of Isolation and ECC

• With iMAT Port-to-port isolation and low far-field correlation are obtained from the same design optimization at the same frequency

• Both result from the condition where the

near fields associated with Port 1 are orthogonal from those associated with Port 2

• The proper conditions are achieved

through resonance and so are inherently optimized to a particular frequency band or bands

Port-to-Port Coupling

Pattern Correlation

frequency

frequency

State 1 State 2

• Aperture tuning in SkyCross tunable antenna modules permits the actual radiating elements to be configured for optimal performance at each desired frequency band

• SkyCross ST-iMAT and Aperture Tuning deliver: Smaller size Improved device performance Network improvement (fewer dropped calls, increased network capacity) Superior performance versus simple feed-point matching

SkyCross ST-iMAT™ (State-Tuned iMAT Antenna Module for Smartphone)

VersiTune-LTE™ Tunable Antenna Module

Smartphone Implementation

iMAT Radiating Elements

Tunable Antenna Module

Tunable iMAT “Isolation Notch” Drives Multiband Antenna Performance

iMAT des ign a llows “contro l” of the is o la tion be tween ports . Drives h igher e ffic iency and lower corre la tion coeffic ien t

• Isolation is a measure of signal interference separation from one feed point to the other • Correlation coefficient is the degree to which the two RF signals are distinct from each other

LTE-700 Corner to Corner Conventional Antenna Design

VSWR: <2:1 Efficiency:

30-40%

CC: >0.8 Coupling:

-4dB

Patterns almost identical

iMAT LTE-700 Antenna Design

VSWR <2.2:1

Isolation:

<-13 dB

Efficiency 50-58%

CC: <0.35

Significantly different patterns

50x100mm GP

iMAT Advantage vs. Dual Antenna: Correlation Coefficient

iMAT Antenna Patterns

Dual Antenna Patterns

Greater pattern diversity results in lower Correlation Coefficient for iMAT vs. Dual Co-polarized Antenna

Independent analysis of iMAT vs. Conventional antenna for handsets shows iMAT delivers significant improvement in Correlation Coefficient

Multiband Antenna Efficiency: ST-iMAT

State 1 State 2 State 3 State 4 State 5 State 6

Sing

le P

ort O

nly Primary

Spec

Diversity Spec

Meas ured Data : S ta te Tuned iMAT configura tion covering a ll LTE and Legacy 3G bands in 6 tun ing s ta tes

• Phone chassis: ~58x120mm • Modular Antenna: x=59mm, y=9.5mm

(from display edge), z=3.7mm Antenna volume (incl. keep out) = 2075mm3 Fully populated antenna module with

speaker, microphone, USB3

Versitune-LTE Antenna Speaker Module Design Example

y =9.5mm

Antenna Elements

Flex PCB Antenna (Double Sided FPCB)

Plastic Carrier With Speaker Box

Embedded Speaker

Audio Port

Microphone

USB Connector

Tuning Components

Versitune-LTE Module Performance Summary

Key Features: • Speaker, Microphone,

USB connector and associated flex films integrated into assembly

• Vibrator, cameras an associated flex films in close proximity to the antenna

• Open Loop tuning with 3 tuning states for each low band: 17, 5, 8

• Supports CA for bands 4 & 17

Versitune Performance Summary Simulations

Main TX Main Rx

Band & Freq Eff

(dB) Goal delta

Eff (dB)

Goal delta

1 1920 - 1980 -2.7 NS -3.9 NS

2 1850 - 1910 -2.9 -3 0.1 -2.6 -6 3.4

4 1710 - 1755 -3.0 -3 0 -3.7 -4 0.3

5 824 - 849 -3.8 -4 0.3 -4.2 -5 0.8

8 880 – 915 -3.4 NS -3.7 NS

17 704 - 716 -3.8 -4 0.2 -4.4 -5 0.7

Free Space Cross Correlation Diversity RX

Band & Freq CC Goal delta Eff

(dB) Goal delta

1 2110 - 2170 0.0 NS -2.8 NS

2 1930 - 1990 0.0 0.5 -0.5 -5.7 -7 1.3

4 2110 - 2155 0.0 0.5 -0.5 -2.4 -7 4.6

5 869 - 894 0.3 0.5 -0.2 -8.0 -8 0

8 925 – 960 0.1 NS -8.1 NS

17 734 - 746 0.4 0.5 -0.1 -5.1 -8 2.9

Versitune LTE Efficiency - Primary/Secondary Port Primary Port

Secondary Port

Performance data includes speaker, cameras, microphone, vibrator, micro USB and associated flex interconnects in the antenna near field

Tuning states 1,2,3

Versitune LTE Coupling (S12) - Primary/Secondary Port Primary Port

Secondary Port


Versitune LTE - Envelope Correlation Primary

Secondary


iMAT 2x2 Antenna

iMAT 2x2 Beam Forming Application

Antenna Beam Forming Problem for Handset Application

• Beam forming is accomplished by combining signals in two or more antennas at different phases

• For conventional antennas, as antenna separation decreases, the benefits of beam forming diminish due to the detrimental effects of antenna mutual coupling

• The separation between antennas, in terms of wavelength, is small for handset and mobile device applications (typically < 0.1 wavelength)

~

~

Antenna Array Combined Signal

Phase Shifter

s <0.1 wavelength at cellular frequencies

• A balanced iMAT design may be well suited for beam forming applications

• Both ports of iMAT antenna can be driven simultaneously

• Applying the same RF signal to both ports with a variable relative phase delay enables a beam forming solution

• Beam forming can provide 3 dB signal gain at the tower for same client device TRP

• Because there are two PAs, each needs to provide only half the total output power of the traditional PA.

Port 1 Excitation

Ф TX

PA

PA

iMAT antenna

Beam Forming – iMAT Technology

Beam Forming Application Analysis Comparing iMAT to Conventional Antennas

Analysis Result – single iMAT antenna produces better beam forming gain than a pair of conventional dipoles

Improvement due to iMAT

Summary

1. LTE-A requirements are driving the need for new, more complex antenna technologies

2. Close attention to the antenna early in the design stage is even more critical due to higher levels of complexity

3. Antenna designs that may utilize a combination of technologies can be used as a competitive advantage that allows for product differentiation

This is truly an exciting time to be a mobile device antenna designer!

THANK YOU!

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