AGaAs PHEMT Distributed Amplifier with Low Group Delay Time Variation for 40 GBit/s Optical Systems

A four stage distributed amplifier MMIC with 11.2 dB ± 1.0 dB gain and a bandwidth exceeding 50GHz has been demonstrated in a commercially available 0.15¿m pseudomorphic GaAs HEMT technology. Group delay time variation from 1.5GHz to 40GHz equals to ± 3.5 ps. When used as preamplifier, biasing can be applied from a single 5.2V supply via the reverse drain load without the need for an expensive external RF-coil for decoupling. The resulting overall power consumption is less than 230mW. The noise figure was measured to be between 5.1 dB and 3.0dB in the band from 3 GHz to 17 GHz. The output voltage swing of the 20GHz fundamental at the 1-dB gain compression is 2.1V, this makes the circuit also suitable as preamplifier for a modulator driver.