SiGe Millimeter-Wave (W-Band) Down-Converter for Phased Focal Plane Array

A millimeter-wave (W-Band) down-converter for Phased Focal Plane Arrays (PFPAs) has been designed and fabricated using the IBM Silicon-Germanium (SiGe) BiCMOS 8HP process technology. The radio frequency (RF) input range of the down-converter chip is from 70 95GHz. The intermediate frequency (IF) range is from 5 30GHz. The local oscillator (LO) frequency is fixed at 65GHz. The down-converter chip has been designed to achieve a conversion gain greater than 20dB, a noise figure (NF) below 10dB and input return loss greater than 10dB. The chip also has novel LO circuitry facilitating LO feed-through among down-converters chips in parallel. This wide bandwidth down-converter will be part of millimeter-wave PFPA receiver designed and fabricated in collaboration with the University of Massachusetts-Amherst Department of Astronomy. This PFPA receiver will be installed on Green Bank Telescope (GMT) / Large millimeter wave telescope (LMT) in Q2 of 2014. This project is collaboration between the University of Massachusetts-Amherst (UMass), Brigham Young University (BYU) and National Radio Astronomy Observatory (NRAO). To the best of the author’s knowledge, this is first wide bandwidth down-converter at W-band to achieve this high gain and low noise figure among Si/SiGe based systems

Flexible high frequency electronics and plasmonics using two dimensional nanomaterials

In this work, we have demonstrated novel flexible electronics and plasmonic devices using 2-dimensional (2D) nanomaterials (graphene and MoS2). The first part of this work is about design of flexible high frequency electronics using 2D nanomaterials. We report sub-THz graphene transistors with fT ~ 100GHz. We also discuss how to integrate graphene based sub blocks (antenna, mixer and speaker) to fabricate all graphene based wireless receiver. We report for the first time flexible RF transistors with GHz frequency response using CVD grown monolayer MoS2. We also demonstrate flexible low power RF nanosystems (amplifiers, mixers, AM receiver) using CVD MoS2. We have developed MoS2 transistor models for integrated circuit design application. RF MoS2 transistors results are very promising for low power internet of things (IOT) applications. In second part, we have shown design of novel plasmonic devices using 2D nanomaterials. We have demonstrated large area tunable graphene metasurface using moiré nanosphere lithography (MNSL). We have shown novel method to fabricate large area graphene nanoribbons (GNRs) using block copolymer lithography (BCPL) and its potential application towards tunable mid-IR plasmonic sensing. We report for the first time nanopatterning of CVD MoS2 on plasmonic substrate using bubble pen lithography (BPL). We have also shown light enhancement of monolayer CVD MoS2 using plasmonic nanoantenna array (PNA). These results are very useful for design of highly efficient 2D nanomaterial based LEDs, photodetectors, lasers and sensors.Electrical and Computer Engineerin

Radio Frequency Transistors and Circuits Based on CVD MoS₂

We report on the gigahertz radio frequency (RF) performance of chemical vapor deposited (CVD) monolayer MoS₂ field-effect transistors (FETs). Initial DC characterizations of fabricated MoS₂ FETs yielded current densities exceeding 200 μA/μm and maximum transconductance of 38 μS/μm. A contact resistance corrected low-field mobility of 55 cm²/(V s) was achieved. Radio frequency FETs were fabricated in the ground–signal–ground (GSG) layout, and standard de-embedding techniques were applied. Operating at the peak transconductance, we obtain short-circuit current-gain intrinsic cutoff frequency, <i>f</i>_T, of 6.7 GHz and maximum intrinsic oscillation frequency, <i>f</i>_max, of 5.3 GHz for a device with a gate length of 250 nm. The MoS₂ device afforded an extrinsic voltage gain <i>A</i>_v of 6 dB at 100 MHz with voltage amplification until 3 GHz. With the as-measured frequency performance of CVD MoS₂, we provide the first demonstration of a common-source (CS) amplifier with voltage gain of 14 dB and an active frequency mixer with conversion gain of −15 dB. Our results of gigahertz frequency performance as well as analog circuit operation show that large area CVD MoS₂ may be suitable for industrial-scale electronic applications