High frequency laser diode (LD) and electro-absorption modulator (EAM)
integrated circuit drivers using a cascaded output switch architecture
that increases the output current and voltage edge speed and reduces the
peaking and ringing of the output waveform, thus improving the
deterministic jitter performance. Also disclosed is a method and
apparatus that provides a modulation current dependence of both turn-on
and turn-off driving currents that lead to an optimal compromise between
the edge speed and output overshoot for a wide range of modulation
currents. A PTAT temperature dependence of both voltage swing and current
level in the predriver assures a low variation of the overshoot and
rise/fall time over a wide temperature range. Using the cascaded output
switch architecture provides an easy way of on-chip summation of the
modulation and bias currents. Biasing the cascode device with a supply
and modulation current dependent base voltage provides an optimum
headroom output switch.