A 32Gb/s NRZ Low-Bias DFB Driver with Frequency Boosting for High Efficiency Data Transmission

This paper presents a 32Gb/s non-return-to-zero (NRZ) distributed feedback (DFB) laser diode driver (LDD) fabricated in 65nm CMOS. The driver is directly wire-bonded to the laser diode without AC-coupling capacitors, which simplifies the packaging and ensures high bandwidth (BW). To improve power efficiency, the active back-termination (ABT) structure is employed to absorb signal reflections with lower power. A continuous time linear equalizer (CTLE), a 3-stage current mode logic (CML) buffer and a pre-driver are employed to compensate the channel loss and achieve a bandwidth extension by providing an estimated gain boosting of 7.5dB at high frequency. The clear electrical eye-diagram of the driver is obtained beyond 40Gb/s, while the measured optical transmission data-rate can still exceed 32Gb/s with a rms-jitter of 2ps. According to the experimental results, the bias current and modulation current of the driver are 40mA and 40mApp, respectively, where the power consumption is 390mW.