- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄376489 > AN649 (Maxim Integrated Products, Inc.) HFTA-04.0: Optical/Electrical Conversion in SDH/SONET Fiber Optic Systems PDF資料下載
參數(shù)資料
| 型號(hào)： | AN649 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | HFTA-04.0: Optical/Electrical Conversion in SDH/SONET Fiber Optic Systems |
| 中文描述： | HFTA - 04.0：光/電轉(zhuǎn)換/ SDH中的SONET光纖系統(tǒng) |
| 文件頁(yè)數(shù)： | 7/11頁(yè) |
| 文件大?。?/td> | 247K |
| 代理商： | AN649 |
systems in which high performance is mandatory and cost is not a major consideration. For
optical links in the majority of telecommunication trunk lines, various types of direct-
modulated semiconductor laser diode offer an optimum cost/performance ratio for short,
intermediate, and long-haul transmissions. Devices are available for operation in both the
second and third optical windows.
All semiconductor laser diodes used for direct modulation have in common the need for a DC-
bias current to set the operating point and a modulation current for signal transmission. The
values for DC-bias and modulation current depend on characteristics of the laser diode, which
can differ from type to type and version to version. The drift of these characteristics with time
and temperature should be evaluated carefully when designing a transmitter unit, especially
with regard to the more cost-effective, uncooled types of semiconductor laser. The laser driver
must therefore offer bias and modulation currents with sufficient range to support the
development of optical transmitters with a wide choice of laser diodes.
To compensate for the drift of laser characteristics over time and temperature, the laser driver
must maintain the initially adjusted DC operating point. The best way to realize this
compensation is to introduce automatic power control (APC). To detect the actual laser power,
a photodiode converts the laser light to a proportional current and feeds it to the laser driver,
where the actual value is compared with a previous fixed value. Any difference causes the DC-
bias current to increase or decrease as required to reach the initially defined laser power.
Often, the APC includes an alarm function that warns if the laser diode's optical power can no
longer be sustained due to aging. Like the operating point, optical signal strength is affected by
the drift of laser-diode characteristics over time and temperature. To maintain the optical
"amplitude," it is necessary to compensate for a decreasing slope in these characteristics caused
by time and temperature. The problem is solved either with additional external circuitry or with
an integrated Automatic Modulation Control (AMC), which may employ the photodiode
already present in the APC loop.
In addition to these fundamental functions, the system must be capable of stopping laser
transmissions by disabling the driver without interrupting data reception at the input. By adding
a flip-flop or latch (as part of the laser driver or the serializer), jitter performance can be
improved by retiming this data stream before it reaches the laser driver's output stage.
Residing between the laser-diode driver and the lower-speed CMOS system components, the
serializer converts parallel data to a serial stream for the laser driver. Like the receiver unit's
deserializer, the serializer's conversion ratio depends on the transmission bit rate and the speed
of the CMOS system interface. The retiming and serialization function requires a transmission
clock, which must to be synthesized. This clock synthesizer can be integrated with the
serializer, and usually incorporates a PLL. The challenge for the synthesizer is to ensure data
transmission with the lowest possible jitter. As a result, the synthesizer plays a key role in the
transmitter of an optical transmission system.
Complete chipset for STM 4 Rx/Tx units
All components of an optical transmission system for telecommunications must comply with
the relevant ITU-T recommendations. Provided this basic requirement is met, the next most
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AN6500 | BUILT-IN REFERENCE VOLTAGE OPERATIONAL AMPLIFIERS |
| AN6500S | BUILT-IN REFERENCE VOLTAGE OPERATIONAL AMPLIFIERS |
| AN6501 | BUILT-IN REFERENCE VOLTAGE OPERATIONAL AMPLIFIERS |
| AN6561L | Dual Operational Amplifiers |
| AN6561 | Dual Operational Amplifiers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AN-649 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Cost, Dual/Triple Video Amplifiers |
| AN6494NSA | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:Digital Communication Orthogonal Modulator IC |
| AN64V6428BQGAM | 功能描述:512MB SDRAM DUAL RANK PC 133 UNB 制造商:atp electronics, inc. 系列:- 零件狀態(tài):在售 存儲(chǔ)容量:512MB 封裝/外殼:144-UDIMM 標(biāo)準(zhǔn)包裝:200 |
| AN6500 | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:BUILT-IN REFERENCE VOLTAGE OPERATIONAL AMPLIFIERS |
| AN6500S | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:BUILT-IN REFERENCE VOLTAGE OPERATIONAL AMPLIFIERS |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。