driving laser diodes - ic-haus · 2 apc or acc? acc apc ... additional tec controller required ......
TRANSCRIPT
Driving Laser Diodes
Uwe M. Malzahn
iC-Haus GmbHIntegrated Circuits
GERMANY
Webinar, April 27, 2006
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 1 / 35
Introduction
iC-HausFounded in 1984 byDr. Heiner Flocke andManfred HerzASiC/ASSP manufacturer(Si-fabless)160 employees world wideAnnual sales $30 millions
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 2 / 35
Introduction
Integrated CircuitsASiCsASSPsAnalogue, DigitalMixed SignalOpto iCs, Hall iCsPower iCsIndustrial and automotiveapplications
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 3 / 35
Introduction
iC-Haus’ third extension38,500 sq ft→ 81,000 sq ft production and R & D floor space→ 6,500 sq ft cleanroom (Class < 10 k)COB packaging facility
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Introduction
Who is Uwe M. Malzahn?Graduated in 1991 from theUniversity Darmstadt in SolidState ElectronicsJoined iC-Haus as an R&Dengineer in 1991Since 2000 Sales andApplications Manager atiC-HausAttending to the laser diodedrivers and optical sensorsamongst others
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 5 / 35
Introduction
Why this webinar?Help to better understand laser diode characteristicsReplace uncertainty with confidence when choosing a driverShed some light onto the working principles of the different driversand operation modesExplain the advantages of integrated laser diode drivers byiC-Haus
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 6 / 35
Outline
1 Characteristics of laser diodesThe laser diode basicsDriver selection criteria
2 APC or ACC?ACCAPC
3 Solutions available by iC-HausWhy use an integrated driver?Operating laser diodes in CW modeOperating laser diodes in pulsed mode
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 7 / 35
The laser diode basics
I(LD)
P(LD)
T = 27 °CT = 40 °C
M−Type N−Type P−Type
I(LD)
P(LD)
T = 27 °CT = 40 °C
M−Type
N−Type
P−Type
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CharacteristicsOptical output vs. laser currentVariation over temperaturePin configuration (if applicable)
What kind of laser diode do we have?
With or without monitor diode?With⇒ output power control (APC)Without⇒ current source resp. current control (ACC)
Do the required currents match the driver’s specification?Driver must provide the required laser diode currentDriver must be able to process the corresponding monitor current
Which pin type configuration?Driver must support the configuration (alternative monitor input?)Power supply must match the configuration (single supply?)
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Laser diode configurations
P−Type
N−Type M−Type
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 12 / 35
How does it work?
ACC(Automatic Current Control)
Constant currentFixed current (no danger ofovercurrent)Requires constanttemperature for constantoutput powerAdditional TEC controllerrequired
Mostly low volume “research”resp. ultra highspeed datatransmission applications
RM
VREF − +
LD
VCC
I(LD)I(LD) const.
P(LD)
P1
T = 27 °CT = 40 °C
P2
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 14 / 35
How does it work?
+
− CI
MD LD
VCC
VREF
RM
I(LD)
P(LD)
P(LD) const.
T = 27 °C
I(LD)1
T = 40 °C
I(LD)2
APC(Automatic Power Control)
Current from the integratedmonitor diode closes thecontrol loopConstant optical output powerRisk of overcurrent with selfheating or ageing effects ofthe laser diode
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Conclusion
iC-Haus ICs focus on APCTargetting industrial clienteleIndustrial sensor principles and applications usually requireconstant optical power
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Why use an integrated driver at all?
IC vs. discrete solutionLower part count (< 1:4)Lower board space ( 1:4)Lower assembly costsHigher reliability (> 4)Excellent performance
High precision (< 1%)High temperature stability (integrated band-gap reference)Integrated reverse polarity protection (iC-WK family)
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 19 / 35
Easy to set up
0.5 VVREF
..47 nF..
OVERTEMP.
TRANSIENT
iC−WK
OVERCURRENT/ ..100 nF..
CIR
..1 uF..
CLDA
LD
AGND
CVCC
MD
LDK
MDK
CI
MDA
NQ
LDA
GNDGND
VCC+2.4..+6 V
5
1 3
4
2
8
7
RM
6
PROTECTION
+
−
D1
FEEDBACK MON.
0.2..50 kΩiC−WK
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Laser/monitor current range covered
iC−WKNiC−WKM
iC−WKP
iC−WKLiC−WK
iC−WJ
iC−WJZiC−WJB
1 mA
100 uA
10 uA
Laser current
Monitor current
100 mA 200 mA 300 mA 350 mA
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 22 / 35
Configurations covered by the iC-Haus CW drivers
Driver IC Optimised for N-type M-type P-typeiC-WK/L N-type yes yes1 yes12
iC-WKN N-type yes yes1 yes12
iC-WJ/Z N-type yes yes1 noiC-WJB N-type yes yes1 noiC-WKM M-type yes1 yes yes2
iC-WKP P-type yes12 no yes
1Laser diode case cannot be grounded2Alternative monitor input utilised
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Modulation
What does “modulation” stand for with CW drivers?“Analogue modulation”Modulation depth 100%Superimposed control loopSinusoidal (or other shape) output
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 24 / 35
Modulation
MDLD
+5 V
+5 V
iC−WJ/WJZ
REF
WDOG22 nFCI
100 nFC2
C1100 uF
10 kΩR2
0..1.5 VVMOD
10 kΩRSET
12ΩR1
2 nFC3
KLD8
CWD2
GND1
CI3
ISET4
AMD
7
IN6
VCC5
3 AGND
2 CI
1 GND
7 LDA
8 LDK
5 MDA 4 MDK
6 VCC
I J
+ −
0.5V
iC−WK
C3 100nF
+VB
100nF C2
1µF
C1
2.2nF C4
200Ω...50kΩR1
3 AGND
2 CI
1 GND
7 LDA
8 LDK
5 MDA 4 MDK
6
VCC
I J
+ −
0.5V
iC−WK/L
C3 100nF
+VB
100nF C2
1µF
C1
2.2nF C4
200Ω...50kΩ
Rmod D/A
GND
R1
How is it done?Modulation of the setup inputUtilising the second monitorinput (iC-WK family only)Maximum modulationfrequency limited by cornerfrequency of the control circuit(typ. several 10 kHz)
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 25 / 35
Pulsed operation
What does “pulsed operation” mean?“On/off” modulationModulation depth near or equal 100%Control priciples
“Switched” CW mode (low frequencies)Averaging control (moderate to high frequencies)“Peak Control” (low to high frequencies)“Burst mode” with a “learned” output power (high to ultra highfrequencies)
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 27 / 35
Frequency range
100 MHz10 MHz1 MHz100 kHz10 kHz1 kHzCW
Frequency
CW Op.
Averaging Ctrl.
100 MHz10 MHz1 MHz100 kHz10 kHz1 kHzCW
Frequency
CW Op.
Peak Ctrl.
Averaging Ctrl.
100 MHz10 MHz1 MHz100 kHz10 kHz1 kHzCW
Frequency
CW Op.
Peak Ctrl.
Averaging Ctrl.
100 MHz10 MHz1 MHz100 kHz10 kHz1 kHzCW
Burst Mode
Frequency
CW Op.
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 28 / 35
The control principles in detail
Switched CW operationiC-WK family, iC-WJ family driversMost simple approachPower on/off or switching inputLimited by turn-on/turn-off time (ca. 1 kHz max.)Pulse delay by turn-on/turn-off time
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 29 / 35
The control principles in detail
Averaging controliC-VJ, iC-WJ family drivers, (iC-HK plus iC-WK)Simple, established approachWorks well with most applicationsLower frequency limited by averaging capacitorRequires fixed duty cycleTurn-on delay
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 30 / 35
Averaging control
+
− CI
MD LD
EN
VCC
VREF
RM
I(MD)
V(CI)
EN
I(MD)
EN
V(CI)
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 31 / 35
The control principles in detail
Peak controliC-NZMost flexible approachWidest operation frequency rangeVariable and wide duty cycle rangeTurn-on delay after long pauses“Burst mode” for very high frequencies
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 32 / 35
Range covered by iC-Haus drivers
iC−HKiC−HKBiC−NZ
iC−WJZiC−WJ
iC−VJiC−VJZ
iC−WJB
iC−WKMiC−WKNiC−WKP
iC−WKiC−WKL
1 kHzCW 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz
Frequency
Laser diode current
300 mA
200 mA
100 mA
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 33 / 35
Conclusion
Benefit from using iC-Haus laser diode drivers!Large range of laser diodes and (industrial) applications coveredby iC-Haus laser diode driversLow part count and board space requiredEasy setupSafe operation and high reliabilityExcellent application support
Uwe M. Malzahn (iC-Haus GmbH) Driving Laser Diodes April 27, 2006 34 / 35
For Further Reading
Uwe M. MalzahnDriving Diode LasersEuroPhotonics, 8/9:22–23 2004.
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