towards a highly-integrated front-end module rf-soi …

TOWARDS A HIGHLY-INTEGRATED FRONT-END MODULEIN RF-SOIUSING ELECTRICAL-BALANCE DUPLEXERS

BAREND VAN LIEMPD

PHD RESEARCHER

IMEC & VRIJE UNIVERSITEIT BRUSSEL

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© IMEC 2015

CONTENTS

Introduction

EBD Challenges

Results

Conclusion & Future work

WARNING: Technical contents ahead…

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© IMEC 2015

CONTENTS

Introduction

- Evolution of the Smartphone

& Highly integrated FEM

- Electrical-Balance Duplexers

EBD Challenges

Results


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© IMEC 2015

SMARTPHONE EVOLUTION2007 2009 2012

iPhone 1st gen iPhone 3GS iPhone 5

Battery & Size ~

Cellular:

4-band – 250Kbps

Connectivity

1-band – 54Mbps

Cellular:

9-band – 100Mbps

Connectivity

2-band – 150Mbps

Battery & Size ~

2016

?

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HIGHER ENERGY EFFICIENCY IS NEEDEDD

ata

rate

san

dN

r. co

nc.

sta

ndar

ds

1995 2000 2005 2010 2015

GSM

GPRS

UMTS

HSPA,

...

HSPA+

LTE, ...

LTE-A,

60 GHz, ...

Battery Capacity

Source: J. Glossner: Trends in Low Power Handset Software Defined Radio, 2007

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COMMUNICATIONS FOR THE I-O-T

A NEED FOR MULTI-STANDARD RADIOS

Cellular Peak data rate of 1Gbps* (DL) and 500Mbps (UL)

4 by 4 MIMO

Carrier aggregation of up to five (non-)contiguous 20MHz channels

In 44 different bands (of which 28 FDD)

256-QAM modulation in 3.4-3.6 & 3.8-4.2GHz

WLAN Supporting peak data rates up to 7Gbps

8 by 8 MIMO

Channel bandwidths up to 80MHz

Carrier aggregation of two (non-) contiguous 80MHz channels

256-QAM modulation

… WPAN, Positioning, Broadcasting

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THE FEM CHALLENGESMARTPHONE EXAMPLE

4-band GSM & 5-band

W-CDMA/LTE incl. Rx diversity:

- >9 SAWs,

- 5 SAW duplexers

- RF switches

- 7 Pas

How to reduce the complexity?

A

S

M

5-band

WCDMA

LTE

TRX

800/900

PA OUT

GSM/

EGSM

bands IN

Cellular

radio

S

W

I

T

C

H

Diversity

RX

Primary

Antenna

Diversity

Antenna

1800/1900

PA OUT

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FEM IS THE FUTURE

STRONG NEED TO REDUCE COST AND

FOOTPRINT DRIVEN BY LTE

Integrated reconfigurable FEM in CMOS SOI?

- Low cost, high performance

- Digital (tuning?) included with passives

- Already in volume-production

Antenna switches

Power amplifiers

Antenna tuners

×Tunable filters/duplexers Hi-FEM

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LONG-TERM VISION (>+3YR)

IMEC HIGHLY-INTEGRATED FEM

RESEARCH (Hi-FEM)

Full TRx context must be considered

Complex multi-dimensional requirements

- Rx: (blocker) linearity & filtering, cascaded losses

- Tx: power efficiency & EVM, harmonics filtering

What does the highly-integrated FEM dream look like?

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Highly integrated Front-End Module (SOI) SCALDIO TRx (bulk CMOS)

LB/MB/HB

Wideband

GM-LNA

Duplexer

(LB/MB/HB)

Antenna

TunerBand-filterSP3T

Matching

&

Harmonics filter

Low-Distortion

PA

HR

GM

HR

8-path mixer

DDRM

LB/MB /HB

SP3T

0.7G-3G

Wideband

antenna

ADC

ADC

D

I

G

I

T

A

L

B

B

Tx Rx

LO

Integrated

balun

BB

LONG-TERM VISION (>+3YR)

IMEC HIGHLY-INTEGRATED FEM RESEARCH

(Hi-FEM)*

Solve problems where they are best solved

High-speed/low-power in bulk CMOS

High-power/high-linearity in SOI CMOS Hi-FEM

* Schematic interpretation only

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© IMEC 2015

CONTENTS

Introduction

- Evolution of the Smartphone

& Highly integrated FEM

- Electrical-Balance Duplexers

EBD Challenges

Results


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© IMEC 2015

ZANT

PA LNA

ZBAL

OPERATING PRINCIPLE

Electrical balance:

ZANT = ZBAL

Electrical Balance Duplexer (EBD)

k

ZANT

ZBAL

PA LNA

fTX

fRX

[Mikhemar et al., VLSI Symp., 2011]

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ZANT

PA LNA

ZBAL

OPERATING PRINCIPLE

Electrical balance:

ZANT = ZBAL

TX leakage


k

ZANT

ZBAL

PA LNA

fTX

fRX


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ZANT

PA LNA

ZBAL

OPERATING PRINCIPLE

Electrical balance:

ZANT = ZBAL

TX leakage

Must be tuned to

maintain balance


k

ZANT

ZBAL

PA LNA

fTX

fRX


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IMEC’S PAST EBD PROTOTYPES

4 prototypes, all functional

Step-by-step, improved understanding and design

Today: Hi-FEM1

DPX V1

ZBAL only

TM

ZBAL

ANTI/O

CSH

T1

R

Csec Cpr

R1

R

C1

RX

out

Lpar

R2C2

TX

in

T2

Lpar

R

R

DPX V2

EBD with real antenna

EU FP7-DUPLO

In-Band Full-Duplex

EBD @ 2.45GHz

Hi-FEM1Breakthrough linearity

2015

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THE ANTENNA INTERFACE

Low loss

Linear

X Not tunable

X Large BoM

4G SAW-based(in products)

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THE ANTENNA INTERFACE

Low loss

Linear

X Not tunable

X Large BoM

4G SAW-based(in products)

EB Duplexer-based(research)

Tunable

Single-chip

? Tuning complexity

? Linearity

? Loss

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Hi-FEM1

Linear

3GPP jammers

27dBm at antenna

Competitive loss

Enabled by

Design techniques

SOI CMOS

EB Duplexer-based(research)

Tunable

Single-chip

? Tuning complexity

Linearity

Loss

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© IMEC 2015

CONTENTS

Introduction

EBD Challenges

- Common-mode vs. Differential-mode

- EB Duplexer Linearity

- RF SOI for highly linear EBD

Results


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Hybrid transformer

+ Allows integration of EBD

ZANT

PA LNA

ZBAL[Mikhemar et al., JSSC, Sept. 2013]

COMMON-MODE VS DIFFERENTIAL

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Hybrid transformer


Need:

Tunable, high-power

sustaining ZBALZANT

PA LNA

ZBAL

PA output

+30dBm

ANT +27dBm

BAL +27dBm

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Hybrid transformer


+ Differential subtraction of transfer paths TX-RX isolation

ZANT

PA LNA

ZBAL

Path 1

Path 2

Differential-mode

+

-

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Hybrid transformer


+ Differential subtraction of transfer paths TX-RX isolation

Capacitive coupling limits CM transfer

[Abdelhalem et al.,

TMTT, March 2013]

ZANT

PA LNA

ZBAL

Differential-mode

Common-mode

+

-

CM leakage

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SINGLE-ENDED DUPLEXER

Hi-FEM1: ground one side of secondary winding

+ Avoids the CM problem

ZANT

PA

LNA

ZBAL

Grounded

sec. winding

Single-ended LNA

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ZANT

PA

LNA

ZBAL

Path 1

Path 2

Leakage cancelled!

Φ

Φ-180°

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+ Cancellation of 2 paths requires impedance compensation

Φ

Φ-180°

ZANT

PA

LNA

ZBAL

Path 1

Path 2

Leakage cancelled!

Impedance

compensation

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+ Cancellation of 2 paths requires impedance compensation

+ Transformer skewing for reduced TX insertion loss

ZANT

PALNA

ZBAL

Skewing

compensation

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CONTENTS

Introduction

EBD Challenges

- Common-mode vs Differential-mode



Results


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ZANT

PA

ZBAL

LNA

EB DUPLEXER LINEARITY

3GPP jammers + TX cause IMD in ZBAL

Switched passive impedance network

Limits linearity

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© IMEC 2015

ZANT

PA

ZBAL

LNA

EB DUPLEXER LINEARITY

3GPP jammers + TX cause IMD in ZBAL

Full-duplex-spaced jammer

Co-channel jammer / triple-beat test

Switched passive impedance network

Limits linearity

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ZANT

PA

ZBAL

LNA

FULL-DUPLEX-SPACED JAMMER

Freq.

+27dBm

TX represented as CW

fTX

Freq.fFD

-15dBm

3GPP out-of-band jammer

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ZANT

PA

ZBAL

LNA


Freq.

+27dBm


fTX

Freq.fFD

-15dBm


Freq.

IM3 generated in ZBAL

fTXfFD fRX

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© IMEC 2015

ZANT

PA

ZBAL

LNA


Freq.

+27dBm


fTX

Freq.fFD

-15dBm


Freq.

IM3 generated in ZBAL

fTXfFD fRX

Freq.

IM3 increases noise floor

fRX

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© IMEC 2015

ZANT

PA

ZBAL

LNA

TX represented as 2-tone

Freq.

+27dBm

fTXFreq.

-43dBm

3GPP co-channel jammer

fCC

CO-CHANNEL JAMMER / TRIPLE-BEAT TEST

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ZANT

PA

ZBAL

LNA


Freq.

+27dBm

fTXFreq.

-43dBm


fCC

Freq.

IM3, IMXMD generated in ZBAL

fTX fCC


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© IMEC 2015

ZANT

PA

ZBAL

LNA



Freq.

+27dBm

fTXFreq.

-43dBm


fCC

Freq.

IM3, IMXMD generated in ZBAL

fTX fCC

Freq.

XMD increases noise floor

fRX

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© IMEC 2015

LINEARITY CONSTRAINTS

For IMD < noise floor:

ZBAL IIP3 >+65dBm (approx.)

Tough, but important

This work: silicon-on-insulator (SOI) CMOS

for RF switch stacking

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© IMEC 2015

CONTENTS

Introduction

EBD Challenges

- Common-mode vs Differential-mode



Results


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© IMEC 2015

KEY ACHIEVEMENTS OF Hi-FEM1

>65dBm balance network IIP3

- Low jammer-caused distortion

- Maintain State-of-the-Art impedance tuning

<4dB insertion loss in 50Ω

In great part, thanks to techno!

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© IMEC 2015

RF SILICON-ON-INSULATOR CMOS

Buried oxide isolates devices

+ High substrate resistance

+ Good passive Q with good RF back-end

Smaller junction parasitics compared to bulk

+ Improved linearity

+ Better RON*COFFn+ n+

BOX (Buried Oxide)

p

sub

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© IMEC 2015

CONTENTS

Introduction

EBD Challenges

Results

- Design highlights

- Measurement results

- Comparison with State-of-the-Art


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© IMEC 2015

TOP-LEVEL SCHEMATIC

Skewed hybrid transformer

RX-side resonance tuned for best RX loss

ZBAL: 4x 8b-tuned C, 2x fixed L, 1x fixed R

Csec

ZANT

ZBAL

PA TM

TXIN

ANTI/O RXOUT

LNA

50Ω C4

C1

C2

C3

L1

L2

ANT

15μm

37μmPA

BAL

LNA

GND

11μm

380μm

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© IMEC 2015




2x CU avoids negative VG,OFF

State-dependent VDC for all nodes

CU CU V2

VB

VSD

V1

VGRG

RB

RSD

CC

VSD

VB

VG

0V

0V

2.5V

2.5V

0V

0V

On Off

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© IMEC 2015

INSERTION LOSS

3.2

3.6

4

Tx IL [dB]

1.8 2 2.2

3.6

4

4.4

Frequency [GHz]

Rx IL [dB]

<3.7

<3.9

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INSERTION LOSS AND RETURN LOSS

3.2

3.6

4

Tx IL [dB]

1.8 2 2.2

3.6

4

4.4

Frequency [GHz]

Rx IL [dB]

<3.7

<3.9

1.8 2 2.2

-60

-25

-10

Tx S11 [dB]

-25

-20

-15

-10

-5

Rx S11 [dB]

Frequency [GHz]

<-20

<-18

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© IMEC 2015

TX-TO-ANTENNA IIP3

Meets 3GPP-Jammer requirements

Result similar to simulated results (PSP)

-130

-70

-10

50

110

0 10 20 30 40 50 60 70 80 90

IM 1,3 @ antenna [dBm]

IM1

IM3 max-code

IM3 min-code

IM3 mid-code

IIP3

70...83dBm

OIP3

67...80dBm

PTX IM1/tone [dBm]

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FULL-DUPLEX SPACED JAMMER TEST

5MHz noise floor1.4MHz noise floor

-140-130-120-110

IM3 @ Rx out [dBm]+24dBm @ antenna

Δ=10dB

10 15 20 25 30Tx input power [dBm]

Jammer power:

0dBm

-5dBm

-10dBm

-15dBm (3GPP max.)

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CO-CHANNEL JAMMER TEST

AKA TRIPLE-BEAT TEST

10 15 20 25 30

-140-130-120-110

XMD @ Rx out [dBm]

Tx input power [dBm]

1.4MHz noise floor

Δ=33dB

Jammer power:

-15dBm

-17.5dBm

-20dBm

-43dBm (3GPP max.)

+24dBm @ antenna

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© IMEC 2015

COMPARISON WITH STATE-OF-THE-ART (1/3)

[1] [2] [3] [4] This work

Tech. [CMOS] 65nm 90nm 90nm 0.18µm 0.18µm SOI

Reference ZANT 50Ω 50Ω 2:1 VSWR PIFA 1.5:1 VSWR

Freq. range [GHz] 1.5–2.1 1.7–2.2 1.7–2.2 1.78–2.0 1.9–2.2

ZBAL tuning dimensions 2 4 4 4 4

Area [mm2] 0.2 0.6 2.2 0.67 1.75

Key specifications

[1] Mikhemar et al., Diff. autotransformer + LNA, JSSC, Sept. 2013.

[2] Abdelhalem et al., Fully diff. hybrid transformer + LNA, TMTT, March 2013.

[3] Abdelhalem et al., Fully diff. hybrid transformer + full RX, TMTT, Sept. 2014.

[4] van Liempd et al., Hybrid transformer (differential output), ESSCIRC, 2014.

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[1] [2] [3] [4] This work

CM isol. [dB] None >60 >60 Poor Single-ended

TX-to-RX isol. [dB] >50 >60 >50 >50 >50

TX IL [dB] 2.5 4.7 4.5 3.0 <3.7

RX IL/casc. NF [dB] 5.0 (NF) 6.7 (NF) 6.7 (NF) 11 (IL) <3.9 (IL)

Small-signal specifications





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[1] [2] [3] [4] This work

PTX,max @ ant. [dBm] <+12 +27 +27 +27 +27

TX-to-ant. IIP3 [dBm] N/A N/A+54

(ZBAL sim.)>+48 >+70

RX-to-ant. IIP3 [dBm] N/A -5.6 inc. LNA -4.6 inc. RX >+32 +72

IMD @ RX [dBm]

(for PTX @ ant.)

FD N/A N/A N/A Poor -124 (+24)

CC N/A -105 (+25.3) -115 (+17.5) Poor -145 (+24)

Large-signal specifications





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© IMEC 2015

CONCLUSION

Single-ended EB duplexer in RF SOI

Enables frequency-flexible Hi-FEM

Avoids common-mode issues

Needs compensation in ZBAL

State-of-the-art performance

>+70 dBm IIP3

Supports 3GPP jammers

Supports ≤+27 dBm at antenna

Competitive loss & tuning capabilities

THANK YOU FOR YOUR ATTENTION

ANY QUESTIONS?

towards a highly-integrated front-end module rf-soi …

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