High-speed Laser Diode Drivers with an Auto-Power Control Technique for Optical Transmission
碩士 === 國立中興大學 === 電機工程學系所 === 94 === One of the most important factors for applying optical system is its cost. Conventionally, high speed optical transceivers are implemented in expensive GaAs process. Nowadays, with the blooming progress in VLSI technology, several GHz front-end circuits in CMOS a...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2006
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| Online Access: | http://ndltd.ncl.edu.tw/handle/38112666770203124064 |
| Summary: | 碩士 === 國立中興大學 === 電機工程學系所 === 94 === One of the most important factors for applying optical system is its cost. Conventionally, high speed optical transceivers are implemented in expensive GaAs process. Nowadays, with the blooming progress in VLSI technology, several GHz front-end circuits in CMOS and SiGe process have been successively demonstrated.
This thesis explores circuit techniques for optical transmitter front-end design in 0.35µm BiCMOS technology. The objective goals of this research are to realize a single chip of 3.3V high speed (3.125Gb/s & 10Gb/s) optical transmitter front-end ICs including laser diode drivers, and auto-power control circuits.
In the thesis two different kinds of laser diode drivers are presented. The output driving value of modulated and bias current can operate form 10mA to 100mA. In order to supply enough current to reach the maximum desired optical output power with a low-efficiency laser and high threshold current under high- temperature.
Because of the strong temperature and age dependence of the laser’s L/I curve, laser diode driver need a feedback mechanism so-called auto-power control (APC) that actively maintains consistent laser diode performance by continuously monitoring the optical output and correcting it for variations caused by changes in operating temperature and laser diode degradation. In the thesis two kinds of APC circuit are presented. One is an analog dual loop control which can maintain constant output power without disturbing extinction ratio another has both analog and digital control mechanism which not only has same advantage of last control mechanism but also can control the bias current more accurate. In order to apply in burst mode optical transmitter the second auto-power mechanism also can store the selected power level in up-down-counter which help the feedback loop to be stable faster.
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