A 60-dB gain, 55-dB dynamic range, 10-Gb/s broad-band SiGe HBT limiting amplifier

A limiting amplifier IC implemented in a silicon-germanium (SiGe) heterojunction bipolar transistor technology for low-cost 10-Gb/s applications is described. The IC employs 20 dB gain limiting cells, input overload protection, split analog-digital grounds, and on-chip isolation interface with transmission lines. A gain enhancement technique has been developed for a parallel-feedback limiting cell. The limiting amplifier sensitivity is less than 3.5 mV/sub pp/ at BER=10/sup -9/ with 2-V/sub pp/ maximum input (55-dB dynamic range). The total gain is over 60 dB, and S/sub 21/ bandwidth exceeds 15 GHz at 10-mV/sub pp/ input. Parameters S/sub 11/ and S/sub 22/ are better than -10 dB in the 10-GHz frequency range. The AM to PM conversion is less than 5 ps across input dynamic range. The output differential voltage can be set from 0.2 to 2 V/sub pp/ with IC power dissipation from 250 mW to 1.1 W. The chip area is 1.2/spl times/2.6 mm/sup 2/. A 10-Gb/s optical receiver, built with the packaged limiting amplifier, demonstrated -19.6-dBm sensitivity. The IC can be used in 10-Gb/s fiber-optic receivers requiring high sensitivity and wide input dynamic range.