Design Of 10Gb/s GaAs/SiGe Preamplifier

Optic-fiber communication was invented in the 1970s, which take the light wave as its data-carrier and the optical-fiber as its transport-medium. Due to its merits, such as great capacity, long transmit distance, and low power dissipation etc, Optic-fiber communication systems have been considered the principal part of information super-highway.Being the forefront of the optical receiver, preamplifier converts the weak current signal produced by PD detecting light wave to amplified voltage signal. To some extent, the performance of a preamplifier decides the performance of the whole optical receiver. Therefore the capability of a competent preamplifier should meet the requirements of all aspects. Current-mode preamplifiers is a transimpedance amplifier with a common gate (or common base) input stage using current shunt feedback technology. Because the current-mode preamplifiers have many advantages, such as high gain, wide band, low noise, and high sensitivity etc, they are widely used in high-speed and ultra-high-speed optical transmission systems.In this project, we designed the current-mode preamplifier for SDH STM-64 (10Gbps) in a 0.2μm GaAs PHEMT technology and a 0.35μm HBT BiCMOS technology respectively. Due to high transit frequency and high transconductance, these two kinds of technology are always the first choice in the design of high-speed ICs. In this paper, we firstly introduce the device composition and the characters of these two kinds of technology; subsequently we analyze the structure of the circuits and describe the design procedure and simulation results based on different technology. Layouts of two circuits are designed after simulation, and they have been delivered to the chip manufacturer and successfully fabricated. The measure results of the GaAs PHEMT preamplifier validate our design specifications. This chip has successfully passed the achievement examination of the 863 program (2003AA31g030)" Research on chip technology of key device of 10-40Gb/s optical transceiver ", and gained a high comment from the experts. Because of the time limitation, the SiGe BiCMOS preamplifier is still waiting for the test.