High gain limiting amplifier for 10 Gbps lightwave receivers

An InP HBT technology developed at Lucent Technologies Bell laboratories, with peak ft-100 GHz is used to design and fabricate a limiting amplifier with high gain and bandwidth margin at 10 Gbps. Feedback techniques are used to obtain >30 dB differential gain with >10 GHz bandwidth for the packaged chip. The design reduces current density with standard cell transistors to improve circuit reliability (at the expense of performance). Stable operating conditions are found by adjusting the DC bias tail currents. The limiting output is set by the current in the output stage. Open eyes are obtained even with >2 V differential output. Depending on the required output swing, the power consumption is 200-500 mW (at Vee~-3.5 to -4.5 V)