1. Analog Devices Proprietary
Analog Devices solutions for Optical Networking
We like to start the brief products introduction of Optical Networks solution from Analog Devices. From the following presentation slides, you can understand more about how Analog Devices provides you the products on the optical system.
Analog Devices Proprietary

2. Analog Solutions for Leading Communications Manufacturers Worldwide
Nortel Networks, Cisco, Ericsson, Lucent, and Motorola rely on ADI products everyday:
Amplifiers and converters
ADSL chipsets
High-performance mixed-signal and RF components for cellular handsets and base stations
High-speed components for fiber optic networks
First of all, I like to introduces Analog Devices Inc. briefly that you may or may not familiar with our products.
Analog Devices is the company to provide high performance mixed Signal and RF components for the Optical fiber communication, ADSL, GSM and Base Station application. Those customers included Nortel, Cisco, Ericsson, Lucent and Motorola.
Analog Devices also is the world wide number 1 marketing share on the High performance Op-Amps and High speed high performance converters.
Analog Devices Proprietary

3. Generic ADM - ADI Presence
Physical
Layer
Framing/
Mapping
Packet
Processing
Backplane
Interconnect
Switch
Fabric
Datapath
TEC Controller
APD Bias Controller
Optical Power Monitor
Optical Supervisor
MEMS Mirror Control
Control
Here is the brief Signal-Chain(block diagram) for the optical fabric communication. ADI is focus on the optical fabric control that’s on the optical physical layer and the section between back-bone and switch fabric such as MEMS mirror control.
On the Physical side, ADI provides: TIA (Trans-Impedance-Amplifier), PA( Post Amplifier), CDR (Clock Data Recovery), LDD (Laser Diode Driver), EEPOT ( Electrical Erasable POTential-meter), Log Amplifier, DC-DC converter , ADC, DAC, Micro-converter and DSP (Digital Signal Processor).
One the back-bone side, ADI provides the Cross-point switches, MEMS(Micro-Electrical Mirror System) mirror control, Low bias amplifier, ADC, DAC and DSP.
Products
TIA, CDR, DEMUX,
MUX/SYNTH, LDD,
EEPOT, Log Amp,
DC-DC Converter,
ADC, DAC, DSP,
MicroController
Crosspoint Switch,
MEMS, FET I/P Amp,
In Amp, MUX, ADC,
DAC, DSP
Analog Devices Proprietary

4. Analog Devices Proprietary
Physical Layer
ADSP21065L – Low Cost SHARC
ADM7xx – Microprocessor Supervisor
ADP333x – LDOs with Any-Cap
ADM103x – Thermal Mgmt and Fan Ctrl
ADN2820 – 10Gbps Trans-impedance Amp (TIA)
AD8015 – 155 Mbps TIA
Framer
Digital
ASIC
Power
Management
TIA PA
CDR
DES
SerialData
Digital
X-POINT
ADN2809 – PA + CDR (Multi-rate to 2.5Gbps)
ADN2811 – 2.5/2.7 Gbps PA + CDR
ADN2812 – Anyrate (10 Mbps to 2.7 Gbps ) Integrated PA+CDR
ADN2815 – Integrated PA+CDR+DES/SER (10 Gbps)
AD808– 622 Mbps PA + CDR
AD807 – 155 Mbps PA + CDR
AD800 – 52 Mbps CDR
FIBER
Coupler
AD8150 – 33x17 Digital X-Point (1.5Gpbs)
AD8151 – 33x17 Digital X-Point (3.2Gpbs)
AD x34 Digital X-Point (3.2Gpbs)
1%- 5%
Framer
Digital
ASIC
Optical Tap
Stratum Clock (PLLs, DDS’s)
SER /
SYNTH
AD985x/3X – DDS
uHz – 500MHz resolution
28/32-Bit Frequency and Phase programmable
AMP
LDD
ADC /
uConverter
FIBER
Here is the detail Signal Chain for the Optical fabric communication physical system. The “black” marked parts mean those parts are released. The “Blue” marked parts mean sampling and the “red” marked parts mean will be released in the next 6 months.
Let’s start from the fiber section. The fiber carries the optical signal from the transmitter. The Photo sensor transfer the optical signal into the electrical signal by the TIA. The PA boosts (amplify) the small electrical signal and provides to CDR. The CDR circuits is to get back the data and clock from the electrical signal with very low jitter. The DESerilizer get the serial data back to parallel data and send to the ASIC to remove the frame header and CRC and get the real data back. Over here, ADI can provides some parts such as the TIA, PA+CDR and Low jitter Clock sources.
If this signal is used for the back-plane or O/E(Optical to Electrical) processing, it could uses the X-POINT digital cross point switches to do the signal routing. Or, this signal can be processed to another data format on the ASIC and send it into the SERilizer. It becomes a serial data and send to Laser Diode Driver to driver the fiber. Here we have: Digital cross point switches, LDD (Laser Diode Driver), EEPOT(Electrical Eraserable Potential-meter) and TEC (Thermal Electrical Cooler) Controller.
If it needs to monitor the receive or the Laser diode output power. Usually, this will used a fiber coupler. The power from the laser coupler is around 1~5% optical power. However, since the optical coupler has very high percentage tolerance (+/-100%), the optical power monitoring amplifier needs to consider the covering range. And, most of the optical power monitoring needs to monitor very wide range current( might down to couple hundred pA and up to few mA). With this high dynamic range signal, The best solution to use is the LOG amplifier that is “linear in dB” to help on this case. After the LOG amplifier, you have to use the ADC (>12bits) to get the digital data. Here we have: LOG Amplifiers, ADC and ADuC (ADC+DAC+8051+flash+memory).
ADuC812 – 8 Channel 12-bit ADC with uC
AD747x – Low Cost 10 and 12-bit ADCs
AD7671 – 1.2 MSPs, 16-Bit ADC
ADSP218x – Low Cost, General Purpose DSP
AD532x – Low Cost 12-bit DACs
AD555X/4x – 14/16Bit Quad Iout DACs
EEPOT
TEC
CTRL
AD8310 – 95dB Log Amp
AD8304 – 160dB Log Amp
AD620 – High Accuracy In-Amp
AD622 – Low Cost In-Amp
AD855x – <50nA bias, <5uV Offset, No Drift
AD854X – <5pA bias, Low Power, low cost
AD pA bias Current
AD8610 – 5pA Bias, 5fA /ÖHz, 6nV/ÖHz
ADN2841 – 155 Mbps to 2.7Gbps Any Rate LDD with Dual Ctrl Loop (5V)
ADN2847 – 155 Mbps to 3.3Gbps Any Rate LDD with Dual Ctrl Loop (3V)
ADN2848 – 155 to 622 Mbps LDD with Dual Ctrl Loop (3V)
ADN2843 – 10Gbps Any Rate LDD with Dual Ctrl Loop
ADN2850 –Dual 10-bit Programmable non-volatile resistor (<35 ppm/C)
ADN8830 – TEC Controller
Analog Devices Proprietary

5. ADI Optical Data Path Products
Part No. Function Samples Release
AD Mbps Clock and Data Recovery (CDR) Available Released
AD Mbps Transimpedance Amp (TIA) Available Released
AD Mbps Post-Amp/CDR Available Released
AD MHz VCO Available Released
AD Mbps Post-Amp/CDR Available Released ADN Gbps Multi-Rate Post-Amp / CDR Sept ‘ Q01
ADN & 2.7 Gbps Post-Amp / CDR Q Q02
ADN Gbps TIA Q H02
ADN Mbps to 2.7Gbps Anyrate Dual-Loop LDD (5V) Available Q01
ADN Mbps to 3.3Gbps Anyrate Dual-Loop LDD (3.3V) Nov ‘ Q02
ADN Mbps to 622Mbps Dual-loop LDD(3.3V) Dec ’ Q02
ADN Gbps LDD with Dual-loop Control, Q H02
ADN Dual Programmable Resistors (LDD calibration) Available 4Q01
Here is the parts ADI provides for the data path signal process on optical fabric communication system. On the right side, it shows those parts’ samples schedule and released date.
Analog Devices Proprietary

6. Multirate Clock and Data Recovery Unit (ADN2809) - Key Features
Multi-rate post-amp and clock-and-data recovery for:
OC-48 / OC-48-FEC
Gigabit Ethernet
OC-12 / OC-12-FEC
OC-3 / OC3-FEC
Also: OC-48/OC48 FEC only CDR (ADN2811)
Adjustable slicing level
Patented six-sigma design for jitter performance. Exceeds SONET/SDH requirements for:
Jitter tolerance
Jitter transfer
Jitter generation
Single reference clock frequency for all rates
This is the ADN2809 for the multi-rate clock and data recovery. Inside this chip, there is a Post Amplifier and a CDR inside. This chip can bypass the CDR to get the amplified signal output without pass the on chip CDR.
ADN2809 provides superior jitter performance than the standard SONET/SDH specifications on the multi-rate application. The low bit rate and high bit rate has same superior performance which is build in two high performance PLLs inside. One of the PLLS provides lower frequency application and another provides higher frequency clock generation. Those frequency range can be selected by two external pins. This chip also build in the adjustable slicing feature for the customers to adjust the eye-diagram move up and down.
ADN2809 is 48-pins LFCSP(7mmx7mm) package.
Analog Devices Proprietary

7. ADN2809 Measured Performance
Here is the performance measurement chart on ADN2809. You can see the OC-48 International Standard(specifications) on the bottom-right side that ADN2809 can provides much better jitter performance than the standard. The jitter specifications(on the top-left side) is much better than the standard too.
Equipment
Limitation!
Analog Devices Proprietary

8. OC-192 / OC-192 FEC Trans-Impedance Amplifier (ADN2820) - Key Features
Trans-impedance: 1400 ohms
Silicon Germanium
Low power dissipation: 100 mW typ
Bandwidth: 8 Ghz
TIA PA
Data
CDR
DES
FIBER
Clock
Input Current Noise: 1.2 uA
Sensitivity: -16dBm
Differential 50 ohm output
Single Bias 5 Volt Operation
Here is the 10Gbps OC-192 TIA for the optical fabric communications system. This chip is base on Si-Ge process that can provide high performance high frequency range operation. The power dissipation also as low as 100mW. This chip also provides 50-Ohm differential output impedance and operated at +5V.
Analog Devices Proprietary

9. OC-48 Laser Diode Driver (ADN2841/ADN2847) - Key Features
OC-48 Any Rate (155 Mbps – 3.3 Gbps) LDDs:
2.7 Gbps 5V Any Rate (ADN2841)
3.3 Gbps 3V Any Rate (ADN2847)
Closed loop control of laser diode average-power and extinction-ratio
Maintains optimal laser diode performance over:
Time (lifetime)
Temperature
Diode process variations
Diode supplier (enables diode 2nd source)
Reduces diode tuning time required at assembly.
High-current drive capability:
Imod up to 80 mA
Available in two package sizes:
32-Pin CSP - 5mm x 5mm
48-Pin CSP - 7mm x 7mm
Here is the Laser Diode Driver (LDD). Both of those two chips(ADN2841 and ADN2847) are support from 155Mbps up to 3.3Gbps(ADN2847) any rate Laser Diode. The differentiation between the Any rate and Multi-rate is: the Any rate LDD can operate with any bit rates of the signal and Multi-rate just support some of the popular bit rate such as OC-3, OC-12 and OC-48/OC-48 FEC.
ADN2841 and ADN2847 are base on the dual loop control mechanism which can monitor and control the Laser power as always as the setting point. No matter the laser diode performance varying in time (lifetime decay), Temperature, Diode process(included the lot to lot variation) and Diode suppliers.
Those two LDD can drive up to 80mA Modulation current without use external MOSFET or Transistor. ADN2841 is +5V operation and ADN2847 is 3.3V. Both of them support two package: 48 pins LFCSP(7mmx7mm) and 32 pins LFCSP(5mmx5mm).
Analog Devices Proprietary

10. OC-3/12 Laser Diode Drivers (ADN2848) - Key Features
Datarates from 155 Mbps to 622Mbps
3.3v operation
Closed loop control of laser diode average-power and extinction-ratio
Maintains optimal laser diode performance over:
Time (lifetime)
Temperature
Diode process variations
Diode supplier (enables diode 2nd source)
Reduces diode tuning time required at assembly.
High-current drive capability:
Imod up to 80 mA
Available in 32-pin 5mm x 5mm CSP package
ADN2848
Data
LDD
SER
FIBER
Clock
Here is the ADN2848 which is a low cost version Laser Diode Driver. This chip functions same as ADN2847 and it is +3.3V operation. Also base on dual loop control mechanism. Data rate support up to 622Mbps.
The Modulation current also up to 80mA and only 32pins LFCSP(5mmx5mm) available.
Analog Devices Proprietary

11. Analog Devices Proprietary
Laser Diode Driver - LDD
THE LASER DIODE DRIVER MUST TRANSMIT THE SERIAL DATA BY DRIVING THE LASER DIODE MAINTAINING THE CORRECT DC BIAS AND AC MODULATION CURRENT VALUES.
THIS IS DONE BY MONITORING THE CURENT FROM THE MONITOR PHOTO DIODE WHICH IS IN THE SAME PACKAGE AS THE LASER DIODE.
From this slide we would like to introduce more about the Laser Diode Driver functions and its operation theory.
The Laser is used to transmit the serial data into the fiber. In order to maintain this Laser diode works correctly. There is a DC-bias current provides to the Laser to make sure the Laser diode is working on the stimulation emission region. This current we called IBIAS (Bias current). The serial data is provides to on-off the signal to the Laser diode. There is an AC modulation current which to decide the laser output power. This current we called IMOD (Modulation Current). The average power is monitored by the photo sensor which on the same package with the Laser diode.
The photo sensor is used monitoring the average power of the Laser diode that control it as the desired power setting. The desired output power is setting by external resistors.
Analog Devices Proprietary

12. Laser Diode Transfer Function - Average Power and Ext Ratio
The optical signal swings between a high and low optical power, digital one and zero.
Average optical power assumes an equal number of ones and zeroes.
Extinction ratio defines the optical signal swing.
Optical
Power
(mW)
Average Power = P1 + P0 2
25 oC
Extinction Ratio = P1 P0 P1
Optical one
On this slide, we can see more details of the Laser diode operation.
At 25o C (The reason we used this is the Laser diode’s bias point and the slope is varying by the temperature), In order to get the signal operates at the stimulated emission region (bigger slope), there is an Ib which the bias current to “bias” the Laser diode. The electrical signal (input signal) is carry on the bias current and determine what’s is the desired output power is.
From the electrical input signal which provides to the Laser diode. The laser diode will generate the optical power output as the diagram shown. If the electrical signal amplitude is change, it also changes the Im which the modulation current and also change the output optical power.
From the Photo sensor point of view, it is monitoring the average power which equal to (P1+ P0)/2. The optical swing is defined on the ER(Extinction Ratio).
Pav
Optical Signal Po
Optical zero Ib Im
Current (mA)
Electrical signal
Analog Devices Proprietary

13. Laser Diode Characteristics Change With Temperature
In an uncooled environment, a laser diode driver must compensate for these changes to maintain a constant optical output.
Optical
Power
(mW)
0 oC
25 oC
70 oC
Here is the slide to show you how the temperature influence the Laser diode operation point.
When the temperature increase, the Laser diode’s efficiency goes low (slope falls off and threshold current increase as well), that’s means the output power from the Laser diode is goes down. If without the temperature compensate mechanism, the output optical power will become lower and lower after temperature increased.
Slope efficiency falls off
Threshold current increases
Current (mA)
Analog Devices Proprietary

14. Analog Devices Proprietary
Analog’s Dual Loop Capability – Allows Laser Driver to Automatically Compensate for Laser Diode Temperature Variations
The ADN2841 maintains constant optical output power levels for the “optical 1” and “optical 0”
Optical
Power
(mW)
Optical
Power
(mW)
Increased Imod
25 oC
70 oC P1 P1
Increased Ibias
Pav
This diagram shows how the basic ADN2841 LDD mechanism works.
On the left side of this slide(25o C), The average power is the average value of the optical power one(P1) and optical Power zero(P0). When the temperature change( say, 70oC here). The Laser diode slope is changed ( it become more un-efficient), the ADN2841 get the slope change information from the photo diode and will increase the Modulation current until get same output optical power.
Unlike with some competitors which the Imod and temperature compensation is setting by external resistors. ADN2841/47 don’t need those extra resistors.
Pav Po Po
Ibias
Imod
Ibias
Imod
Current (mA)
Current (mA)
Analog Devices Proprietary

15. ADN2841 and ADN2847 Optical Performance Results
Temperature Extinction Ratio Average Optical Power
( oC) ( dB ) (dBm )
Extinction Ratio Range = 0.61dB
Average Power Range = 0.56 dB
Here is some testing results we get from the the Mitsubishi FU-455 Laser diode worked on ADN2841 and ADN2847’s Evaluation board. You can see when the temperature change, the Extinction ratio and Average power doesn’t get too big change based on the ADN2841/47’s dual loop control mechanism.
Notes:
Laser used = Mitsubishi FU-445, ( typical tracking error = 0.5 dB ).
Measurement taken from ADN2841 Optical Demo Board Rev C.
Analog Devices Proprietary

16. Analog Devices Proprietary
Optical Eye Diagram – ADN2841 5v operation
这是采用ADN2841设计的评估板测出的没有进行滤波的2.5Gbps光眼图
2.5 Gbps unfiltered optical eye at 25 oC, Mitsubishi FU-445 laser diode and ADN2841.
Analog Devices Proprietary

17. Analog Devices Proprietary
Optical Eye Diagram – ADN2841 5v operation
这是采用ADN2841设计的评估板测出的滤波后的2.5Gbps光眼图
2.5 Gbps filtered optical eye at 25 oC, Mitsubishi FU-445 laser diode and ADN2841.
Analog Devices Proprietary

18. Analog Devices Proprietary
Optical Eye Diagram – ADN v operation
这是采用ADN2847设计的评估板测出的没有进行滤波的2.5Gbps光眼图
2.5 Gbps unfiltered optical eye at 25 oC, Mitsubishi FU-445 laser diode and ADN2847.
Analog Devices Proprietary

19. Analog Devices Proprietary
Optical Eye Diagram – ADN v operation
这是采用ADN2847设计的评估板测出的滤波后的2.5Gbps光眼图
2.5 Gbps filtered optical eye at 25 oC, Mitsubishi FU-445 laser diode and ADN2847.
Analog Devices Proprietary

20. OC-192 / OC-192-FEC Laser Diode (ADN2843) Key Features
155Mbps to 10.7 Gbps operation
Direct Drive, no AC coupling required
3.3Volt Operation
First 10 Gbps LDD to market with closed loop control of laser diode average-power and extinction-ratio
Leverages architecture developed for ADN2841
High-current drive capability:
Imod up to 60 mA
+3.3V
ADN2843
FIBER
Data
LDD
SER
Clock
ADN2843是一颗OC-192/STM-64 速率以下的任意连续速率激光驱动器，由于该芯片的速率还在设计中，可能最后实际的最高速率可达到12.5Gbps 或13Gbps.供电电压为3.3V，对消光比和平均功率采用了双环控制技术。调制电流可达到60mA.
Analog Devices Proprietary

21. Dual Programmable Resistors (ADN2850)
Enables automated set-up of laser bias and modulation current levels
Programmable laser calibration, minimizes setup time during assembly
Non-volatile memory for set-point storage
Industry’s lowest temperature coefficient by 10X (35 ppm/oC typical)
10-bit resolution - Largest range available. Full-scale values:
25 Kohms
250 Kohms
Available in 2 package types:
LFCSP - 5mm x 5mm, 16-pin
TSSOP - 5mm x 6.5mm, 16-pin
ADN2850 used to set LDD nominal values for:
Average Power
Extinction Ratio
By adjusting resistance value to ground on PSET and ERSET
通常在LDD的应用中，需要电位器来调整设定消光比和平均功率，这种电位器一般是需要高精度，低温漂，尤其是在DWDM的应用中。而ADN2850就是为这种需求而设计的。它的温漂为35ppm/oC ，精度为10比特( 1024个点可调)。芯片内部有 Flash存储器，可记忆以前的设置，这样在掉电重起后，可以自动恢复以前的设置。ADN2850有25K 和250K 欧姆两种。封装也有两种。
Analog Devices Proprietary

22. Backplane Electronics
Common
Data Format
Common
Data Format
ATM Cells
SONET Frames
PHY
ASIC
XPT
XPT
ASIC
PHY
Fiber
Fiber
N-1
N-1
PHY
ASIC
ASIC
PHY
N-1
N-1
PHY
ASIC
ASIC
PHY
PHY
ASIC 1 N
ASIC
PHY
ATM Card
OC3 Drop Card
Common
Data Format
Common
Passive
Serial
Backplane
Full Or
Partial
Mesh
IP Packets
Data Format
SONET Frames
PHY
ASIC
XPT
XPT
ASIC
PHY
Fiber
Fiber
N-1
N-1
PHY
ASIC
ASIC
PHY
N-1
N-1
PHY
ASIC
ASIC
PHY
PHY
ASIC 2
N-1
ASIC
PHY
通常在通信产品中，在背板部分需要进行数据的交换。上图就是一个例子。各种类型，速率的数据在背板进行交换。找到一种高速，多通道的交换芯片，对于背板和系统设计是非常重要的。
IP Card
OC3 Drop Card
SMPTE
259/292
Common
Data Format
SONET Frames
PHY
CODEC
XPT
XPT
N-1
N-1
ASIC
ASIC
PHY
N-1
N-1
ASIC
ASIC
PHY
PHY
CODEC 3
N-1
Video Card
OC12 Trunk Card
Analog Devices Proprietary

23. AD8152 X-streamTM 34x34, 3.2 Gb/s/port Digital Crosspoint Switch
3.2 Gb/s per Port NRZ Data Rate
- Supports SONET, OC-48 Standard w/ FEC
Wide Power Supply Range: +2.5 V, +3.3 V
- Programmable Iout up to 25mA
Lowest Power: <2.5W, No Heat Sink Required
50 ohm Termination Resistors on-board
34x34, Fully Differential, Non-blocking Array
Suitable for Giga-bit Ethernet and OC-48 optical network switching.
Fully differential signal path reduces jitter and crosstalk using singled ended voltage swing
Lowest cost solution for 3.2GB/s, 34x34 ($195)
Compact 256L SBGA package, 0°C to +85°C.
Also see AD8151: 33x17, 3.2 Gb/s/port Digital Crosspoint Switch, 184L LQFP
AD8152是34x34通道高速交叉矩阵，每个通道的最高速率达3.2Gb/s( 不归零数据 )，可以支持Giga-bit, OC-48/STM-16数据交换，输出电流可驱动至25mA。另外，ADI还有较少通道 17x34的 AD8151芯片。
Analog Devices Proprietary

24. EDFA Control Loop (High Power)
LOG AMPS
AD8304 – 160dB Log Amp
AD8310 – 95dB Log Amp
Digital POT
ADN2850 – Dual 10-bit EEPOT (<35 ppm/C)
Transimpedance AMPs
AD825 – 10pA Ibias
AD8610 – 5pA Ibias
ADCs
AD767x – Family of 16-bit ADCs (Hi Precision AND Low Cost)
AD747x – Low Cost 10 and 12-bit ADCs
AD789x – Low Cost 12 and 14-bit ADCs
DACs
AD554x – Family of 16-bit DACs (Single and Quad)
AD555x – Family of 14-bit DACs (Single and Quad)
AD5532 – 14-bit DACs, 32 Channels
Multiplexers
ADG738/426 – 16 Channel Multiplexer (Low RON)
ADG732 – 32 Channel Multiplexer (Low RON)
DSPs
ADSP-21065L – Low Cost SHARC
ADSP218x/91 – Low Cost, General Purpose DSP
ADSP-21161N – Low Cost SIMD SHARC
TEC Controller
ADN8830 TEC Controller
DAC
Erbium Doped Fiber Amplifier
Isolator
Isolator
1-5%
Coupler
1-5%
Coupler
WDM
WDM
I/P
Power
adj
O/P
Power
adj
Pump
Pump
TEC
TEC
DAC
ADC
DAC
ADC
图示是一个输出高功率，控制速度需要很快的EDFA模型，所以采用了高速低价的DSP作为控制用的MCU。同时，因为为了控制EDFA中TEC(半导体温差制冷器), 可以采用AD8830单片TEC控制器。DSP也通过一些AD转换器和DA转换器来控制TEC控制器及泵浦。为了检测动态范围大光功率，可以采用对数放大器来将大范围的电流转变成小范围变化的信号。AD8304是专为光通信设计的一颗对数放大器，动态范围可达160dB。
TEC Control
LOG
AMP
ADC
DAC
TEC DRV
TEC Control
LOG
AMP
ADC
DAC
DAC
TEC DRV
ADC
Ther Mon
EEPOT
ADC
Ther Mon
ADC
TEC
Bias
EEPOT
DSP
ADC
TEC
Bias
Analog Devices Proprietary

25. Analog Devices Proprietary
EDFA Control using uConverters
Erbium Doped
Fiber Amplifier
Isolator
Isolator
Coupler 1%
Coupler
WDM
WDM
WDM 1%
Input
Power
adj
Output
Power
adj
Pump
Pump
Pump
LOG
AMP
LOG
AMP
TEC
TEC
TEC
TEC Control
TEC Control
TEC Control
TEC DRV
TEC DRV
TEC DRV
Ther Mon
Vt set
Ther Mon
Ther Mon
Vt set
Vt set RC
AMP
对于那些要求控制速度不是很快的EDFA，就不必采用DSP作为控制的MCU，可以采用ADI的一颗称为Microconverter的综合处理器ADuC812。它内置一颗8052单片机的内核，并且有8K字节的片内Flash存储器，8通道的12位，200KSPS的AD转换器，两个12位电压输出的DA转换器。该芯片不需要任何开发工具，可以在PC机上将编译好的程序通过ADuC812的SPI口下载。同时，它内置的记数器也可以作为PWM输出，再通过一个RC网络对ADN8830进行温度设置。该芯片还内置了WatchDog. RC
AMP
PWM
12B
DAC
12B
DAC
PWM
AMP
ADuC812 2x
12Bit
DACs
8052 Core
SPI
8X 12Bit ADCs
Analog Devices Proprietary

26. MEMs Control & Measurement
Control Electronics for a Cross-Connect Fabric
‘All ADI’ Closed Loop Mirror Control
16-Bit DAC
250V 50uA ~
AD767X
16-Bit ADC
ADG732
32:1
MUX
14/16-Bit DAC
250V 50uA
Discrete Drivers
Multi channel Inst Amps
Multi channel 16-Bit DACs
Multi channel MEMs Mirrors
Multi channel Buffer Amps
Multi channel FET I/P Amps
ADSP21065L
DSP
在全光交换通信中，精确控制微机电系统是个关键。上图是一个全光交换的控制电路，全部都是采用ADI的产品来完成的。因为需要高速控制，所以采用ADSP-21065L作为主控制器。
AD767X
16-Bit ADC
ADG732
32:1
MUX
16-Bit DAC ~
REF
16-Bit DAC
One Vref Per 32 (used for calibration)
Analog Devices Proprietary

27. Analog Devices Proprietary
FIBER
OPTICAL
COUPLER
1% .. 5%tap of main power
98% of power continues down fiber
Measurement
Amp
Vout ~ Pin
Traditional Methods
Vbias
Vbias
Vbias
TIA
In - Amp
Log Amp
Wide Range
Good Precision
Easy to Calibrate
pros
Simple
High Speed
Simple
Good Precision
上面是一个TIA(传输跨阻运放)，In-Amp（仪表放大器），Log Amp（对数放大器）的对比。TIA与Log Amp相比，虽然简单高速，但是动态范围小，而且温度特性较Log Amp要差。AD8304是ADI最新推出的面向光通信中的功率测量的一款芯片，它宽至160dB的动态范围足可以应付各种光通信设计，包括DWDM应用。
Poor Range
No Temp Comp
Requires Cal
Limited Range
Requires Cal
Higher ASP
Lack of ICs
cons
ADI
Part
AD825 – 10pA Ibias
AD8610 – 5pA Ibias
AD854X – 5pA Ibias
AD620, AD622,
AD629, AMP02
AD8304 – 20MHz 160dB
AD8310 – 500MHz, 92dB
Analog Devices Proprietary

28. Analog Devices Proprietary
Benefit of AD dB Dynamic Range (100pA – 10mA) Logarithmic Amp versus a TIA
这是一个TIA 和Log Amp的输入输出对比图。从上图我们可以看见，传统的TIA为了达到所需的测量范围，需要通过改变跨阻阻值来实现。而且从曲线的特性可以知道，在放大器的后级，需要一个很高精度的AD转换器，通常是14/16比特。而Log运放的后一级就只需采用12比特或以下精度的AD转换器就可以。
Log Amp covers wide dynamic range, classical transimpedance amplifiers (TIAs) require a specific transresistance to cover a desired range.
Analog Devices Proprietary

29. ADN8830 TEC Controller Simplified Block Diagram
Features:
High efficiency: >90%.
Low noise operation: < 1% ripple in TEC current
Frequency and phase compensation in the control loop.
Long term temperature stability: 0.01C.
Open/Short & thermal protection
Programmable maximum current limit.
External
Compensation
Network
P-Channel
(Upper MOSFET)
N-Channel
Thermistor
PWM Control
MOSFET Driver
Temp
Measure
Temp Set
这是一个TEC控制器芯片ADN8830的功能框图。Temp Measure是个温度测量模块，Temp Set是预设目标温度，Current Limit是设置输出电流最大值，Wave Locker Input用于在波长锁定的应用场合，可以直接将温度锁定在某个点。Phase control用于调整输出电流的相位，这在一块PCB板有多个ADN8830时是很有用，可以防止供电电流的过冲。Frequency control（100KHz-1MHz)决定了输出电流的频率，频率越低，效率越高，但输出电流的外接滤波电感值就需要越大。
Current Limit
Wave Locker Input
P-Channel
(Lower MOSFET)
N-Channel
OSC
Voltage Reference
Vref
Phase Control
Frequency Control
Analog Devices Proprietary

30. Analog Devices Proprietary
ADN8830 Application L1 P1 C3
SSTART NC
VCC R4
COMPOSC
SYNCIN
SYNCOUT
VTEC
Thermistor
VLIM
PGND
VREF
ANALOG DEVICES
ADN8830
TEC_C
Rth N1 NC
TEC
COMPSW1
THRMIN R8
VSET
TEMPSET NC
FREQ
COMPSW2 R7
AGND
TEC_H
THRMFAULT P2
TEMPLOCK
TEMPOUT
COMCTL
COMOUT
COMIN PH SD N2
上图是ADN8830的典型应用电路。ADI会提供推荐用的场效应管的型号和电感的型号，以及各种设定阻值的计算方法。 R9
R1, R2, R3, C1, C2
Compensation Network R4
Voltage limit
R5, R6
Temperature set point R7
Switching frequency adjustment R8
Temperature adjustment R9
Switching phase adjustment
L1, C3
Output Filter R1 R2 R3 C1 C2
Analog Devices Proprietary