The future of agriculture is moving towards a more technological and efficient way to produce food for the world’s population. One key resource for that is water. A radiometer design is introduced that will be used to determine the feasibility of an 800g C-Band (6.8 GHz) radiometer for fixed-wing UAVs, giving agronomists a new cutting-edge tool to measure soil and kernel moisture in cereal grain pods. Simulation tools and computer-aided optimization were used to develop multiple design iterations, which were manufactured and measured to assess the performance of the proposed radiometer. A custom HEMT LNA was designed using ADS EM co-simulation, resulting in a 10dB gain and 1dB noise figure. The proposed system design has a theoretical NEΔT of 0.28 K and a preliminary measured NEΔT of 0.535K at 36.9ms integration time, respectively.

This article reports the first accurate and physics-based Verilog-A implementation of the fully analytic form of photocurrent in SPICE compact models for uni-traveling carrier (UTC) photodiodes (PDs). To overcome the limitations of single-pole network implementations for modeling frequency dependence of the photo-response, especially at frequencies beyond 100 GHz, we explored different solutions for the complete analytic equation of the dynamic photocurrent. A new implementation has been proposed which requires three additional nodes in the UTC-PD electrical equivalent circuit and offers the best tradeoff between accuracy and computational efficiency. Model validation has been performed against on-wafer measurements from two UTC-PD technologies depicting very good accuracy over the entire frequency range.

This paper presents Si/SiGe:C and InP/GaAsSb HBTs which feature specific assets to address submillimeter-wave and THz applications. Process and modeling status and challenges are reviewed. The specific topics of thermal and substrate effects, reliability, and HF measurements are also discussed.