A 10Gb/s Laser-Diode Driver with Active Back-Termination in 0.18μm CMOS

A laser-diode driver (LDD) requires output transmission-line back-termination that absorbs signal reflection from the imperfectly terminated load, especially when a low-cost laser diode is used to build a high-speed optical transmitter. Otherwise, it may lead to degraded waveform fidelity and reduced eye-mask margin. Conventional LDDs implement the passive back-termination with on-chip resistors due to its simplicity (H.M. Rein et al., 1994). However, the passive termination resistor inevitably becomes an additional load for the output driver, which results in significant decrease of the modulation current range.To enable low-cost and flexible CMOS solutions, this paper presents a low-voltage design topology of active back-termination by incorporating the design techniques described above.