lowlow--power cmos power cmos--drivendriven ......[m. fields, avago, ofc 2010, paper otup1] current...

LowLow--Power CMOSPower CMOS--DrivenDrivenTransmitters and ReceiversTransmitters and Receivers

© 2010 IBM Corporation

Benjamin G. LeeBenjamin G. Lee, Clint L. Schow, Alexander V. Rylyakov,, Clint L. Schow, Alexander V. Rylyakov,Fuad E. Doany, Richard A. John, Jeffrey A. KashFuad E. Doany, Richard A. John, Jeffrey A. KashIBM T. J. Watson Research Center

Conference on Lasers and Electro-Optics | May 2010 | San Jose, CA

Evolution of Optical Interconnects

WAN, MANmetro,long-haul

LANcampus, enterprise

Systemintra/inter-rack

Boardmodule-module

Modulechip-chip

Chipon-chip buses

1980’s 1990’s 2000’sTime of Commercial Deployment (Copper Displacement):

> 2011

DeployedOptical Links

CMB5: Low-Power CMOS-Driven Transmitters and Receivers © 2010 IBM Corporation2

Distance 10’s – 100’s km 100 m – 2 km< 10 m intra< 100 m inter

< 1 m < 10 cm < 2 cm

Density (Gb/s/mm2)

10-3 10 1000

Cost ($/Gb/s)

1000 1 10-5

Power (mW/Gb/s)

500 5 0.5

# of lines 10’s 1M’s100’s 1k’s 10k’s 100k’s

TelecomTelecom DatacomDatacom ComputercomComputercom

TerabusProgram

Integration requiredto meet cost, power,and density targets.


Computercom Copper Displacement

IBM Roadrunner (2008)IBM Roadrunner (2008)

[M. Fields, Avago, OFC 2010, paper OTuP1]

IBM Blue Waters (2011)IBM Blue Waters (2011)Current System Implementations

microPODTM paralleloptical TX/RX

Fiber to the RackFiber to the Rack50,000 optical links

Fiber to the ModuleFiber to the Module1,000,000 optical links


Hub/switch module, with IC and 56 microPODs

Active optical cables plugged into back of switch rack

Node DrawerNode Drawer

[A. Benner, IBM, OFC 2010, paper OTuH1]


TRX2:

16TX + 16RX

TRX1:

16TX + 16RX

980-nm Terabus Full Optical Link (320 Gb/s)[F. Doany et al., T. Adv. Packaging 2009]


16 Channels TRX1 → TRX2 at 10Gb/s + 16 Channels TRX1 ← TRX2 at 10Gb/s

Terabus ProgramTerabus ProgramOptical Links over PCB


TRX2:

16TX + 16RX

TRX1:

16TX + 16RX

980-nm Terabus Full Optical Link (320 Gb/s)[F. Doany et al., T. Adv. Packaging 2009]

Now moving to industry standard 850-nm wavelength range for:


16 Channels TRX1 → TRX2 at 10Gb/s + 16 Channels TRX1 ← TRX2 at 10Gb/s

Terabus ProgramTerabus ProgramOptical Links over PCB

850-nm wavelength range for:1. Increased commercial availability

of OE components, and2. Decreased losses (or extended

reach) in polymer waveguides.


RX ICRX ICTX ICTX IC

-HighHigh--speed probe padsspeed probe pads

VCSEL arrayVCSEL array

850-nm Terabus Transceiver§ Previously Demonstrated 130-nm CMOS, 24-Channel TRX at 850 nm§ Scale to 90-nm CMOS for Power, Speed, and Area Improvements


Silicon CarrierSilicon Carrier

VCSEL arrayVCSEL arrayPD arrayPD array

Silicon Carrier

PCB and Waveguides

RX IC

Organic Carrier

TX IC PDVCSEL

Lens Array

12.5

Gb/

s/ch

[F. Doany et al., ECTC 2008]


Transmitter Single-Channel Analog IC

Custom Laser Diode Driver

VDD_PA

RL2

M2M1

ILD

VCSELx1 x2 x3 x5x4

VDD_OS VDD_LD

I0

RL1

L1


Custom Laser Diode Driver• 0.027 mm2 circuit area• common-anode VCSEL connection for low power• series inductor peaking at the output (L1)

VCSEL [N. Li et al. OFC 2010]• fabricated by Emcore Corp.• 6.5-µm aperture diameter• sub-mA threshold current• 3-dB electrical bandwidth of 14 GHz

Sample VCSEL Eye: 20 Gb/s, 6 mA, 25°C 1 mm1 mm


Transmitter Performance (231–1 PRBS)15.0 Gb/s15.0 Gb/s

(26.7 ps/div)(26.7 ps/div)17.5 Gb/s17.5 Gb/s

(22.9 ps/div)(22.9 ps/div)12.5 Gb/s12.5 Gb/s

(32 ps/div)(32 ps/div)20.0 Gb/s20.0 Gb/s

(20 ps/div)(20 ps/div)

0.75 pJ/bit0.75 pJ/bitprevious record: 1.5 pJ/bit at 10 Gb/s *

11.2 mW (7.5 mV/div)11.2 mW (7.5 mV/div)

10.0 Gb/s10.0 Gb/s(40 ps/div)(40 ps/div)

19.6 mW (10 mV/div)19.6 mW (10 mV/div)

130-nm àààà 90-nm• > 3× power reduction at PNOM

• 2× reduction in E/b with 1.5×speed increase at PLOW

• ~ 2× area reduction• BER < 10-12 verified

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0.5

mW

0.5

mW

PP--PP


previous record: 1.5 pJ/bit at 10 Gb/s *

66.5 mW (20 mV/div)66.5 mW (20 mV/div)1.1 pJ/bit1.1 pJ/bit

3.3 pJ/bit3.3 pJ/bit

19.6 mW (10 mV/div)19.6 mW (10 mV/div)

Fibe

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0.7

mW

0.7

mW

PP--PP

1.3

mW

1.3

mW

PP--PP

* [S. Nakagawa et al., OFC 2008, paper OThS3, 2008]


Receiver Single-Channel Analog IC

_Predriver

PD

VDD_CORE

TIA

VDD_IO

Chip Boundary (0.056 mm2)

LA Output Buffer

Photodiode:• Fab’d by Emcore Corp.• 25 µm diameter• R = 0.55 A/W

(QE = 0.8)• IDARK = 0.1 nA• C = 80 fF• BW > 20 GHz

[N. Li et al., OFC 2010]1 mm1 mm


Cherry-Hooper LATransimpedance Amplifier

5 stages

RPD

RPD

CAC

CAC

LIN

LIN

M1 M2

LL LL

RL RL

IIN

VDD_CORE

VPD

I1

LFRF LF RF

Vout-

Vout+

Vin-

VDD_CORE

Vin+M1 M2

R1

I1

M3 M4

R1R2

I2

R2

Vout-

Vout+

R3R3

VDD_IO

Vout-

Vout+

M1 M2

RL RL

I1

Vin-

Vin+

Output Buffer


Receiver Performance (27–1 PRBS)

2.6 pJ/bit2.6 pJ/bitpreviously 4.0 pJ/bit in 130-nm CMOS

39 mW (50 mV/div)39 mW (50 mV/div)


Inci

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t Ave

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Opt

ical

Pow

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cide

nt A

vera

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al P

ower

0.4

mW

0.4

mW

PP--PP

15.0 Gb/s15.0 Gb/s(26.7 ps/div)(26.7 ps/div)

17 Gb/s17 Gb/s(23.5 ps/div)(23.5 ps/div)




130-nm àààà 90-nm• open eye at 20 Gb/s (from 15

Gb/s) at PHIGH

• 1.5× reduction in E/b at PLOW


previously 4.0 pJ/bit in 130-nm CMOS

89 mW (50 mV/div)89 mW (50 mV/div)3.5 pJ/bit3.5 pJ/bit

4.5 pJ/bit4.5 pJ/bit


Inci

den

t Ave

rage

Opt

ical

Pow

erIn

cide

nt A

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al P

ower

0.4

mW

0.4

mW

PP--PP

0.6

mW

0.6

mW

PP--PP

Reference transmitter used high-speed VCSEL driven with 40-Gb/s Pattern Generator.


Receiver Performance (27–1 PRBS)

5 Gb/s, 39 mW5 Gb/s, 60 mW10 Gb/s, 39 mW10 Gb/s, 60 mW12.5 Gb/s, 39 mW12.5 Gb/s, 60 mW


12.5 Gb/s, 60 mW15 Gb/s, 39 mW15 Gb/s, 60 mW

~ 50% increase in power improves sensitivity by ~ 3 dB at 15 Gb/s


90-nm CMOS-Driven TX & RX Results

§ Simultaneously Optimized for Power, Speed, and Area§ Demonstrated Improvements from 130-nm Designs

[Schow et al., JLT 27 (7) 915]

NominalNominalSettingsSettings

TX Power (mW)

TX Speed (Gb/s)

TX Area (mm2)

RX Power (mW)

RX Speed (Gb/s)

RX Area (mm2)

130 nm 73 15 0.050 62 12.5 0.050


§ Lowest TX E/bit: 0.75 pJ/bit at 15 Gb/s§ Lowest RX E/bit: 2.6 pJ/bit at 15 Gb/s§ Sum of TX+RX Powers: 50 mW§ Next Steps

– 24-channel TRX assemblies with 90-nm CMOS

– Complete link through optical PCB at 850 nm

130 nm 73 15 0.050 62 12.5 0.050

90 nm 20 15 0.027 60 15 0.056

This work has been partially supported by DARPA through

the Chip to Chip Optical Interconnects (C2OI) Program.


Extra Slides



Transmitter Performance (27–1 PRBS)

0.75 mW/Gb/s0.75 mW/Gb/s

11.2 mW (7.5 mV/div)11.2 mW (7.5 mV/div)

19.6 mW (10 mV/div)19.6 mW (10 mV/div)






BER < 10BER < 10--1212 verifiedverified

Coup

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Opt

ical

Mod

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ion

Am

plit

ude

Coup

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Opt

ical

Mod

ulat

ion

Am

plit

ude

--2.9

dB

m2.

9 dB

m


67 mW (20 mV/div)67 mW (20 mV/div)1.1 mW/Gb/s1.1 mW/Gb/s

3.3 mW/Gb/s3.3 mW/Gb/s

19.6 mW (10 mV/div)19.6 mW (10 mV/div)

Fibe

rFi

ber--

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led

Opt

ical

Mod

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Am

plit

ude

Coup

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Mod

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Am

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--1.5

dB

m1.

5 dB

m+1

.1 d

Bm

+1.1

dB

m

lowlow--power cmos power cmos--drivendriven ......[m. fields, avago, ofc 2010, paper otup1] current...

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