A 4-PAM 20-Gbps CMOS Laser Driver with Tunable Active Back-Termination

• Main Authors: Su, Kai-Ti, 蘇凱悌
• Other Authors: Chen, Wei-Zen
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/70861542907795658014

碩士 === 國立交通大學 === 電子研究所 === 99 === Conventional laser diode drivers adopt passive back-termination as impedance matching; however it consumes additional power on passive load. In this thesis we propose a new active back-termination for laser driver. It consumes less power dissipation compared to conventional driver with passive back-termination. Moreover, for pervasive adaptation, the active back-termination is tunable with reference resistor to match the characteristic impedance of transmission line. At the meantime, we use a pre-distortion circuit to compensate the on/off asymmetry of the laser diode. In order to achieve a higher data rate under the bandwidth limitation, the quadri-pulse amplitude modulation is used. In this way the total data rate is doubled under the same bandwidth. The Gray code is adopted to reduce the bit error rate (BER), since there is only one-bit changed between different levels. The laser diode driver is fabricated in TSMC 90nm CMOS process. Under 1.2Vand1.8V supply, the delivered data rate can reach 16Gbps, power consumption is about 100mW, and the die area is 0.53mm2.