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50-500 GHZ Wireless: Transistors, ICs, and System Design
[email protected] 805-893-3244
Plenary, 2014 German Microwave Conference, 10-12 March, Aachen
Mark Rodwell University of California, Santa Barbara
Coauthors:
J. Rode, H.W. Chiang, T. Reed, S. Daneshgar, V. Jain, E. Lobisser, A. Baraskar, B. J. Thibeault, B. Mitchell, A. C. Gossard, UCSB
Munkyo Seo, Jonathan Hacker, Adam Young, Zach Griffith, Richard Pierson, Miguel Urteaga, Teledyne Scientific Company
50-500 GHz Electronics: What Is It For ?
Video-resolution radar→ fly & drive through fog & rain
Applications100+ Gb/s wireless networks near-Terabit
optical fiber links
820 GHz transistor ICs today
109 1010 1011 1012 1013 1014 1015
Frequency (Hz)
microwaveSHF*
3-30 GHz10-1 cm
mm-waveEHF*
30-300 GHz10-1 mm
op
tical
38
5-79
0 T
Hz
sub-mm-wave THF*
0.3-3THz1-0.1 mm
far-IR: 0.3-6 THz
ne
ar-IR
10
0-38
5 T
Hz
3-0
.78
m
mid-IR6-100 THz50-3 m
*ITU band designations
** IR bands as per ISO 20473
2 THz clearly feasible
50-500 GHz Wireless Has High Capacity
very large bandwidths available
short wavelengths→ many parallel channels
harray widt
wavelength resolutionangular
1/2 RBN
NDB
R22 distance)th/(wavelengarea) (aperturechannels#
Sheldon IMS 2009Torkildson : IEEE Trans Wireless Comms. Dec. 2011.
3
50-500 GHz Wireless Needs Phased Arrays
R
dtransmitte
received eRP
P
2
2
isotropic antenna → weak signal →short range
highly directional antenna → strong signal, but must be aimed
no good for mobile
beam steering arrays → strong signal, steerable
32-element array → 30 (45?) dB increased SNR
must be precisely aimed →too expensive for telecom operators
Rrt
dtransmitte
received eR
DDP
P
2
2
Rtransmitreceive
transmit
received eR
NNP
P 2
2
50-500 GHz Wireless Needs Mesh Networks
Object having area~lR
will block beam.
Blockage is avoided using beamsteeringand mesh networks.
...high-frequency signals are easily blocked.
...this is easier at high frequencies.
50-500 GHz Wireless Has High Attenuation
High Rain Attenuation
0.1
1
10
100
109 1010 1011 1012
Rai
n A
tten
ua
tion
, d
B/k
m
Frequency, Hz
100 mm/Hr
50 mm/Hr
30 dB/km5
0 G
Hz
five-9's rain @ 50-1000 GHz: → 30 dB/km
very heavy fog
High Fog Attenuation
~(25 dB/km)x(frequency/500 GHz)
Olsen, Rogers, Hodge, IEEE Trans Antennas & Propagation Mar 1978 Liebe, Manabe, Hufford, IEEE Trans Antennas and Propagation, Dec. 1989
50-500 GHz links must tolerate ~30 dB/km attenuation
4
mm-Waves for Terabit Mobile CommunicationsGoal: 1Gb/s per mobile user
spatially-multiplexed mm-wave base stations
mm-Waves for Terabit Mobile CommunicationsGoal: 1Gb/s per mobile user
spatially-multiplexed mm-wave base stations
or optical backhaul
mm-wave backhaul
140 GHz, 10 Gb/s Adaptive Picocell Backhaul
140 GHz, 10 Gb/s Adaptive Picocell Backhaul
350 meters range in five-9's rain
PAs: 24 dBm Psat (per element)→ GaN or InPLNAs: 4 dB noise figure → InP HEMT
Realistic packaging loss, operating & design margins
60 GHz, 1 Tb/s Spatially-Multiplexed Base Station
2x64 array on each of four faces. Each face supports 128 users, 128 beams: 512 total users.Each beam: 2Gb/s.200 meters range in 50 mm/hr rain
PAs: 20 dBm Pout , 26 dBm Psat (per element)LNAs: 3 dB noise figure
Realistic packaging loss, operating & design margins
400 GHz frequency-scanned imaging radar
What you see with X-band radarWhat your eyes see-- in fog
What you would like to see
400 GHz frequency-scanned imaging car radar
400 GHz frequency-scanned imaging car radar
Image refresh rate: 60 Hz
Resolution 64×512 pixels
Angular resolution: 0.14 degrees
Aperture: 35 cm by 35 cm
Angular field of view: 9 by 73 degrees
Component requirements: 50 mW peak power/element, 3% pulse duty factor6.5 dB noise figure, 5 dB package losses5 dB manufacturing/aging margin
Range: see a football at 300 meters (10 seconds warning) in heavy fog (10 dB SNR, 25 dB/km, 30cm diameter target, 10% reflectivity, 100 km/Hr)
50-500 GHz Wireless Transceiver Architecture
III-V LNAs, III-V PAs → power, efficiency, noiseSi CMOS beamformer→ integration scale
...similar to today's cell phones.
backhaul
endpoint
High antenna array gain → large array area→ far too large for monolithic integration
III-V PAs and LNAs in today's wireless systems...
http://www.chipworks.com/blog/recentteardowns/2012/10/02/apple-iphone-5-the-rf/
Transistors for
50-500 GHz systems
17
THz InP HBTs: Performance @ 130 nm Node
0
4
8
12
16
20
24
28
32
109 1010 1011 1012
Gai
n (d
B)
Frequency (Hz)
U
H21
f = 480 GHz
fmax
= 1.0 THz
Aje = 0.22 x 2.7 m2
UCSB: V. Jain et al: 2011 DRC Teledyne: M. Urteaga et al: 2011 DRC
UCSB: J. Rode et al: unpublished
BVCEO=4.3 V
3-4 THz Bipolar Transistors are Feasible.
Needs:
very low resistivity contacts
very high current densities
narrow junctions
Impact:
Efficient power amplifiers,complex signal processingfrom 100-1000 GHz.
Ultra Low-Resistivity Refractory Contacts
Performance sufficient for 32 nm /2.8 THz node.
Low penetration depth: ~ 1 nm.
Refractory: robust under high-current operation.
10-10
10-9
10-8
10-7
10-6
10-5
1018 1019 1020 1021
N-InGaAs
B=0.6 eV
0.4 eV0.2 eV
0 eV
Electron Concentration, cm-3
Co
nta
ct R
esi
stiv
ity
, c
m2
step-barrierLandauer
1018 1019 1020 1021
N-InAs
Electron Concentration, cm-3
0.2 eVB=0.3 eV
step-barrier
B=0 eV
0.1 eV
Landauer
1018 1019 1020 1021
P-InGaAs
Hole Concentration, cm-3
B=0.8 eV
0.6 eV0.4 eV0.2 eV
step-barrierLandauer
32 nm node requirements
Baraskar et al, Journal of Applied Physics, 2013
Refractory Emitter Contact and Via
sputtered,dry-etched W/TiW via
low-resistivityMo contact
Refractory metals→ high currents
Needed: Much Better Base Ohmic Contacts
base
Needed: Much Better Base Ohmic Contacts
emitter
TiPd
Au
TiPd
Au
base
emitter
~5 nm deep Pt contactreaction
(into 25 nm base)
Pt/Ti/Pd/Au(3.5/12/17/70 nm)
Two-Step Base Contact Process
1) Blanket deposit 1nm Pt2) Blanket deposit 10nm Ru
(refractory)3) Pattern deposit Ti/Au
Surface not exposed to photoresist→ less surface contamination 1 nm Pt layer: 2-3 nm surface penetrationThick Au: low metal resistance
Two-Step Base Contact Process
0 100
5 1019
1 1020
1.5 1020
2 1020
2.5 1020
0 5 10 15 20 25
dopi
ng, 1
/cm
3
depth, nm
2 nm doping pulse
1018 1019 1020 1021
P-InGaAs
10-10
10-9
10-8
10-7
10-6
10-5
Hole Concentration, cm-3
B=0.8 eV
0.6 eV0.4 eV0.2 eV
step-barrierLandauer
Co
nta
ct R
esis
tivi
ty,
cm
2
32 nm noderequirement
Increased surface doping: reduced contact resistivity, increased Auger recombination.
→ Surface doping spike 2-5nm thick.
Need limited-penetration metal
"Near-Refractory" Base Ohmic Contacts
THz InP HBTs
a few more things to fix ...
2-3 THz Field-Effect Transistors are Feasible.
3 THz FETs realized by:
Regrown low-resistivity source/drain
Very thin channels, high-K dielectrics
Gates scaled to 9 nm junctions
Impact:Sensitive, low-noise receiversfrom 100-1000 GHz.
3 dB less noise → need 3 dB less transmit power.
III-V MOS Development→ Benefits THz HEMTs
VLSI III-V MOS THz III-V MOS
-0.2 0.0 0.2 0.40.0
0.4
0.8
1.2
1.6
2.0
Gm
(mS
/m)
Curr
ent D
ensi
ty (m
A/
m)
Gate Bias (V)
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2VDS
= 0.1 to 0.7 V
0.2 V increment
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70.00.20.40.60.81.01.21.41.61.82.02.22.4
Curr
ent D
ensi
ty (m
A/
m)
Drain Bias (V)
Ron
= 201 Ohm-m
at VGS
= 1.0 V
VGS
= -0.4 V to 1.0 V
0.2 V increment
III-V MOS:results @ 18nm Lg
InP HBT Integrated Circuits: 600 GHz & Beyond 614 GHz fundamentalVCO
340 GHz dynamic frequency divider
Vout
VEE VBB
Vtune
Vout
VEE VBB
Vtune
620 GHz, 20 dB gain amplifierM Seo, TSCIMS 2013
M. Seo, TSC / UCSBM. Seo, UCSB/TSCIMS 2010
204 GHz static frequency divider(ECL master-slave latch)Z. Griffith, TSCCSIC 2010
300 GHz fundamentalPLLM. Seo, TSCIMS 2011
220 GHz 180 mWpower amplifier T. Reed, UCSBCSICS 2013
600 GHz IntegratedTransmitterPLL + MixerM. Seo TSC
Integrated 300/350GHz Receivers:LNA/Mixer/VCOM. Seo TSC
81 GHz 470 mWpower amplifier H-C Park UCSBIMS 2014
220 GHz 180mW Power Amplifier (330 mW design)
2.3 mm x 2.5 mm
T. Reed, UCSBZ. Griffith, TeledyneTeledyne 250 nm InP HBT 30
PAs using Sub-λ/4 Baluns for Series-Combining
31
17.5dB Gain, >200mW PSAT, >30% PAE
Power per unit IC die area* =307 mW/mm2 (pad area included)=497 mW/mm2 (if pad area not included)
80-90 GHz Power AmplifierPark et al, 2013 CSICS
to be presented, 2014 IEEE IMS:
to be presented, 2014 IEEE IMS:
50-500 GHz Wireless Electronics Mobile communication @ 2Gb/s per user, 1 Tb/s per base station
Requires: large arrays, complex signal processing, high Pout , low Fmin
VLSI beamformersVLSI equalizersIII-V LNAs & PAs
III-V Transistors will perform well enough for 1.5-2 THz systems.
0
4
8
12
16
20
24
28
32
109 1010 1011 1012
Ga
in (
dB
)
Frequency (Hz)
U
H21
f = 480 GHz
fmax
= 1.0 THz
(backup slides follow)
35
Low transmitter PAE & high receiver noise are partially offset using arrays,
Effects of array size, Transmitter PAE, Receiver Fmin
10-2
10-1
100
101
102
103
10 100 1000
4 dB Noise Figure, 20% PAE: 84 W Minimum DC Power
Po
we
r, W
att
s
# of transmitter array elements, # of receiver array elements
PA saturated ouput power/element
PA total DCpower consumption
Phase shifter+distribution+LNADC power consumption
total DC power
0.2W phase shifters, 0.1 W LNA
10-2
10-1
100
101
102
103
10 100 1000
10 dB Noise Figure, 5%PAE: 208 W Minimum DC Power
Po
we
r, W
att
s
# of transmitter array elements, # of receiver array elements
PA saturated ouput power/element PA total DC
power consumption
Phase shifter+distribution+LNADC power consumption
total DC power
0.2W phase shifters, 0.1 W LNA
Large arrays: more directivity, more complex ICsSmall arrays: less directivity, less complex ICs
→ Proper array size minimizes DC power
but DC power, system complexity still suffer
200 mW phase shifters in TRX & RCVR, 0.1 W LNAs
50-500 GHz Wireless Has Low Attenuation ?
Wiltse, 1997 IEEE Int. APS Symposium, July
Low attenuation on a sunny day
2-5 dB/km
75-110 GHz
200-300 GHz125-165 GHz