© imec 19991

BroadbandWirelessCommunication

© imec 2001

The world is going wireless !

> Wireless LANsexperience agrowing success inenterprises.

> Wireless homegateways are themissing piece in fastinternet and videoaccess.

> Wireless personalnetworks will opennew serviceopportunities

Enterprise WLAN

Wireless homegateway

Wireless personalnetwork

© imec 2001

Wireless Requirements

> Cost < 10$

> Power consumption < 100 mW

> Network capacity > 100 Mbps

> Range > 50 m

ðIMEC’s Mission: “To enable low costand low power integrated solutionsfor the next generation broadbandcommunication networks”

© imec 2001

Long term strategy executed in aphased approach

phase 1 phase 2 phase 3

home gatewaywith extended

range andcapacity

enterpriseWLAN

OFDM

Turbo codingSDMA

QoS MAC5 GHz FE SIP

high datarateterminals

ScalabilitySIP

personal areanetwork

MIMO

© imec 2001

OFDM Modem Architecture

Mapper IFFTFFT

Symbolreorder

CFOComp

EqualizerDemapper

Time Sync &Gain Comp

© imec 2001

Improved equalizer for betterperformance with QAM

QAM64 BER performance

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

12 13 14 15 16 17 18

SNR per bit (dB)

bit

err

or

rate

Improved equalizer

Standard equalizer

© imec 2001

Second generation OFDM Modem

> 0.18m CMOS 5LM

> 20MHz

> 160 PQFP

> 431 kgates

> 19 RAMs

> 20.8mm2

> Ptx = 199mW

> Prx = 212mW

© imec 2001

Wireless set-up at 5.2 GHz

© imec 2001

Long term strategy executed in aphased approach

phase 1 phase 2 phase 3

home gatewaywith extended

range andcapacity

enterpriseWLAN

OFDM

Turbo codingSDMA

QoS MAC5 GHz FE SIP

high datarateterminals

ScalabilitySIP

personal areanetwork

MIMO

© imec 2001

IMEC’s solution: WLAN-in-a-package

BiCMOS RF ASIC

Mixed-signal CMOS ASIC(s):OFDM modem, memory,

microprocessor, peripherals,FPGA

MCM-D interconnecttechnology- glass substrate- Cu interconnections

© imec 2001

System model includes 4 mostimportant front-end impairments

© imec 2001

PA can be operated with only 15dB back-off (IIP3 - Pin)

© imec 2001

Phase noise must be K<-32dBcfor a Lorentzian model

© imec 2001

Demonstrator: Single-package5 GHz receiver RF module

LNA

LNA with bare die pHEMT transistor(EC2612)

Two 5 GHz MCM Bandpass Filters

GaAs (pHEMT) bare die downconversion mixer(TGC1411)

5 GHz WLAN

© imec 2001

Single-package 5 GHz receiverRF module

Mixer:conv. gain: 15 dBpower: 25 mA @ 3V

BPF-LNA-BPF-mixer:gain: 22.4 dBNF: 7.8 dBP-1dB: -25 dBm (input)size: 6.5 x 7 mm2

© imec 2001

LO

LNA

Vcc

Tuning

Bias

Out2Out1

500 MHz IF

0.35 um BiCMOS

24 GHz fT

3.3 Volt supply

MCM-D technology

Chip-package co-designtrade-offs in VCO design

Co-Design of ASIC and MCMallows optimal trade-offs

© imec 2001S

2

m

osc2 P

FkT2ff

Q1

S⋅

⋅

⋅∝Φ

Vcc

Tuning

Bias

Out2Out1

Q LC tank

inductorsvaractorsphase noise

(dBc/Hz@ 100 kHz)

Power(mW)

on-chipQ=5.5

MCMQ=50

MCMQ=50

on-chipQ=17

on-chipQ=17

off-chipQ=40

-86

-90

-92

17.8

9.5

7.9

FOM

167

173.7

176.5

=

dc

20

P)f(L1

ff

log10FOM∆∆

(simulated results)

3 versions with constant output power

Better VCO performance withhigh-Q MCM passives

© imec 2001

4.7 GHz VCO with MCM-Dinductors

© imec 2001

Complete RF Transceiver in asingle package

Size:16 x 16 mm2

LO

VGA

AmpPA

PLL

LNA IF SAW

IF SAW

© imec 2001

Next step: from antenna to DC ina single package

> Direct downconversion

> Polar upconversion

> power amp in the package

> eventually, antenna in the package

© imec 2001

Transmitter architectureexploration

PA

Switchingpower supply

Fractional-NSynthesizer

Digitaldivider

VCO

Phase feedback

Amplitude (envelope) signal

Modulatedphase signal

Polar upconversion

© imec 2001

Single-package implementationand demonstration

LO

VGA

AmpPA

PLL

LNA IF SAW

IF SAW

Optimization of poweramplifier chain

Power device MCM

Board

© imec 2001

Long term strategy executed in aphased approach

phase 1 phase 2 phase 3

home gatewaywith extended

range andcapacity

enterpriseWLAN

OFDM

Turbo codingSDMA

QoS MAC5 GHz FE SIP

high datarateterminals

ScalabilitySIP

personal areanetwork

MIMO

© imec 2001

Turbo Decoding Scheme> Iterative decoding: D1 → D2 → D1 → D2 → ...

> A decoder module (D) for each encoder (C)

> Increasingly good solution:

closer to maximum likelihood decoding

Decoder

Π

C 2

C 1

ΠD 1 Π

Π -1

Encoder

U C Y

Û

D 2

© imec 2001

Turbo coding significantlyimproves performance

BER

Eb/No (dB)

© imec 2001

05

10152025303540

area(mm2)

energy(mJ/bit)

latency(ms)

datarate

(Mb/s)

PCCC non-optPCCC opt

*3.9 /20.9 /568 *323

Systematic memory optimiza-tions reduce power consumption

> Systematicoptimizationimproves:

• power

• decoding delay

• data rate

> At the costof area

© imec 2001

Spatial Division Multiple Access(SDMA)

wired backbone

> Improves bandwidth efficiency. Systemcapacity increases with number of antennas

> By exploiting spatial diversity

> Antenna array processing at basestation forTx and Rx

> OFDM reduces the complexity of basebandSDMA processing

© imec 2001

OFDM / SDMA Architecture withPer-carrier Processing

RF Front End

OFDMmodem

RF Front End

OFDMmodem

RF Front End

OFDMmodem

...

...

......

...

r1

r2

rk

SDMA

SDMA

SDMA

© imec 2001

OFDM/SDMA MultipliesNetwork Capacity

• 1 user@ 25 Mbps1 antenna

• 4 users@ 25 Mbps4 antennas

• Same bandwidth !

• Better performances !U = 1A = 4

U = 4A = 4

U = 1A = 1

© imec 2001

Multimedia home gatewayrequires a QoS MAC

155Mb/s WLAN 5GHz

MPEG 4>100 Gop/s 5 Gtr/s 10 Watt

WWW

Reconfigurableappliances

Broadbandsatelliteaccess

© imec 2001

Long term strategy executed in aphased approach

phase 1 phase 2 phase 3

home gatewaywith extended

range andcapacity

enterpriseWLAN

OFDM

Turbo codingSDMA

QoS MAC5 GHz FE SIP

high datarateterminals

ScalabilitySIP

personal areanetwork

MIMO

© imec 2001

Medical sensorSatellite

navigatorWatch

PDA

Credit card

Wireless Personal Networkenables new applications

Mobile phone

Camera

© imec 2001

Multiple Antennas :Scalability of Link Capacity

nT x nR channels

Total Transmitted power is the same

Link Capacity x n

BS UT

1 channel

BS UT

... ...

© imec 2001

SC-CP offers OFDM performancewith low PAPR

IDFT

X +

h nD

FT

Ser/P

ar 1H P

ar/S

er

© imec 2001

Scalability with Hybrid OFDM

Small andLow cost

Rich andfancy

© imec 2001

Capacity search : link adaptationto avoid fading margin

SNR

Bits/s/Hz Capacity

Throughput

20 dB

© imec 2001

generation

propagation impact

Substrate noise coupling is aproblem for integrated radio’s

© imec 2001

Substrate noise spectral peaks40 dB larger than noise floor

-160

-140

-120

-100

-80

-60

0 50 100 150 200 250 300 350 400 450 500

Vsub [dB]

Freq [MHz]

Ringing

40 dB

© imec 2001

Applying the analysis to theWLAN OFDM baseband chip

> Mixed-signal IC in0.35 um digitalCMOS

> embedded 8-bitADC

> digital up/down-converter andcomplex filter

> WLAN modem

> noise sensors

© imec 2001

Our Goals

> Mid term goals:• demonstrate a high performance wireless

home gateway: turbo coding, SDMA, QoSMAC.

• Demonstrate an integrated 5GHz front-end.

> Long term goals:• single-package radio for personal area

networks.

• High datarate multi-antenna terminals.