A 30-GHz Integrated Subharmonic Mixer based on a Multichannel Graphene FET

A 30 GHz integrated subharmonic mixer based on a single graphene field effect transistor (G-FET) has been designed, fabricated and characterized. The mixer is realized in microstrip technology on a 250 um high resistivity silicon substrate. In order to enhance the current on-off ratio, the G-FET utilizes a channel consisting of an array of bow-tie structured graphene, yielding a current on-off ratio of 7. A conversion loss (CL) of 19 ± 1 dB over the frequency range of 24 to 31 GHz is obtained with an LO to RF isolation better than 20 dB at an LO power of 10 dBm. The overall minimum CL is 18 dB at 27 GHz. The mixer has a 3 GHz ±1-dB IF bandwidth, which is achieved with a fixed LO signal of 15 GHz. The mixer linearity is characterized and the highest third order intercept point is measured to be 12.8 dBm