© 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.