Characterization of Graphene FET based 200 GHz Mixer and 1 GHz Amplifier Integrated on a Si Substrate

Other conference contribution, 2018

arises for new materials and technologies which can be used in the millimeter wave and terahertz wave regime. In this context, a receiver is an important component to be developed.
It converts the received signals into useful information. A typical heterodyne receiver consists of an antenna, RF and IF filters, RF and IF amplifiers, and a mixer. The amplifiers and the mixer can be based on field effect transistors (FETs). To obtain high speed transistors the charge carrier mobility and
velocity in the transistor channel should be high. Therefore, the 2D material graphene is an interesting material since it has a high room temperature charge carrier mobility and a high saturation velocity [1].
In previous works a 10 dB small-signal amplifier designed for 1 GHz [2] and a 185-215 GHz subharmonic resistive mixer [3] (designed for a center frequency at 200 GHz) based on graphene FETs (GFETs) have been demonstrated. The amplifier was further developed in [4] and the lumped
inductor for matching used in [2] was replaced by an planar inductor. The measured and modeled gain for the two inductor types are shown in Fig. 1. The gain is reduced from 10 dBm to 5 dBm when using the planar inductor compared to the lumped inductor. The model shows that the gain can be increased to the designed gain of 10 dBm if the inductor resistance is reduced to Rs =5 by increasing the thickness of the gold conductor to 2 m.
Additionally, the mixer design in [3] has been improved compared to the mixer design in [5] by decreasing the loss in the coplanar waveguid (CPW) circuit using air bridges.
In this work, both, the amplifier and mixer are integrated together on a single silicon substrate and the characterization results are presented.