50-500 GHZ Wireless: Transistors, ICs, and System Design

rodwell@ece.ucsb.edu 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