A versatile Si-bipolar driver circuit with high output voltage swing for external and direct laser modulation in 10 Gb/s optical-fiber links

Broadband SiGe HBT Amplifier Concepts for 40 Gbit/s Fibre-Optic Communication Systems

“…5. Double emitter-followers are used to perform high-speed decoupling [8]. A capacitive emitter degeneration is introduced to the two cascode stages in order to trade gain for a higher cut-off frequency.…”

Driving high-speed VCSELs

“…The design of a laser diode driver (LDD) is a challenging task, since clear eye diagrams at high speeds require abrupt signal edges and low jitter. Traditionally, LDDs were designed to drive edgeemitting lasers (EELs) and were based on differential-pair topologies acting as current-pulse sources for the laser diodes [1]. This choice of circuit topology is straightforward for EELs exhibiting low series resistance, which is very often combined with considerable series parasitic inductance.…”

A Breakdown Voltage Multiplier for High Voltage Swing Drivers

“…Hence, the transfer function for the main path can be described as (7) Similarly, the auxiliary path's transfer function is modeled as (8)…”

“…While most of the building blocks in a fiber optics transceiver have been implemented and demonstrated in silicon at 10 Gb/s and above [1]- [6], the optical modulator electrical driver, for output voltages over 3 Vpp, has been primarily done in compound semiconductors [7]- [11]. This is mainly due to breakdown limitations of silicon transistors and large required voltage swings of today's high-speed optical modulators.…”

“…Such a large voltage swing poses a challenge for silicon-based transistors (SiGe HBT [6], [7], [12]- [14] or Si CMOS [15]) whose breakdown voltages are constantly dropping with continuous scaling for higher speed. While there have been reports of driver circuits in SiGe for optical applications, most of these circuits drop the entire voltage swing across single transistors and thus cannot exceed the collector-emitter breakdown voltages, and are, hence, limited to a voltage swing of around 3 V. Kanda et al used a driven-cascode topology in InP HEMT without the timing adjustment capacitor [16], and Li and Tsai [17] have recently demonstrated additional improvement to our original proposed BV-Doubler topology [20].…”