Design Of 2.5G CMOS Burst Laser Driver

With the development of society and the development of science and technology,people’s demand for communication and information is getting higher and higher,the exchange of information is increasing day by day.It is imperative to establish highspeed and high-data transmission system.Optical fiber communication system is the rapid development of this requirement,with its high bandwidth and low attenuation and other advantages of more and more widely used.The passive optical network(PON)transmission system with fiber as the transmission medium is an important development mode of fiber to the home(FTTH).Based on the Global Foundry 0.13μm CMOS process,a 2.5G CMOS burst mode laser driver circuit for passive optical network system is designed.The laser driver consists of a reference circuit,a laser driver core circuit and a self-test circuit.The reference circuit includes a bandgap reference and an LDO that provides bias current,bias voltage,and internal power conversion to the laser driver core circuitry.Burst mode laser driver core circuit consists of input buffer circuit,polarity flip circuit,burst enable circuit,equalizer,cross point control circuit,output pre-driver circuit and output stage nine circuit.The self-test circuit generates a square wave with a frequency of 6.68 MHz for a ring oscillator with process and temperature compensation.The basic function of the laser driver core circuit is tested to save the cost of the test and reduce the cost.When the process angle is changed,the maximum variation of the oscillation frequency of the designed ring oscillator only is 1.288 MHz.The oscillation frequency of the ring oscillator is designed to be stable with the change of the oscillation frequency.Using the Specter simulation software to simulate the laser driver circuit,the LDO circuit completes the internal power conversion of 3.3V to 1.5V,the loop gain is 86.6dB,and the loop phase margin is 64.8?,the low frequency Power supply rejection ratio of 78 d B.The reference voltage of the bandgap reference is only 1.78 mV in the range of-40°C to 125°C,and the low power supply rejection ratio is 82.59 dB.Laser driver core circuit for 50? typical load resistance of the simulation of the eye diagram of the signal cycle 400 ps that the working rate of 2.5Gbit/s,rise and fall time of 70 ps,burst enabled switching time is less than 2ns,the modulation voltage range of 0 ~ 900 mV,the bias voltage range of 0 ~ 900 mV.