InP based high gain Ka-band three stage coplanar waveguide monolithic amplifier

This paper demonstrates a comparison of two three-stage Ka-Band amplifiers in CPW-technique. The first MMIC is based on AlGaAs/GaAs HEMT devices with a gate length of 0.25μm. The second MMIC is realized with 0.25μm InAlAs/InGaAs HEMT devices on InP. Both of the applied types of transistors, the GaAs and the InP HEMT are characterized by a similar lateral layout. Therefore the idea has been investigated of making use of the identical circuit layout in both applications, the GaAs as well as the InP MMIC. Measurements demonstrate a gain of 18dB and 29dB for the GaAs and the InP amplifier, respectively. This increase of 11dB in gain confirms the benefit of the idea to just replace GaAs HEMT devices by InP based HEMTs in the same circuit layout. Especially in the case of MMICs in CPW technique the advantage of increased transconductance and reduced feedback capacitance of the InP HEMTs compared to their GaAs counterparts is achievable without any restriction concerning the circuit realization and chip handling.