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(pp) at BER = 10(-9) with 2-V(pp) maximum input (55-dB dynamic range). The total gain is over 60 dB, and S(21) bandwidth exceeds 15 GHz at 10-mV(pp) input. parameters Sri and S-zz 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(pp), with IC power dissipation from 250 mW to 1.1 W. The chip area is 1.2 x 2.6 mm(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.