JPL has been developing the Water Hunting Advanced Terahertz Spectrometer on an Ultrasmall Platform (WHATSUP) instrument to detect water on comets, asteroids, and other planetary bodies. This next generation THz molecular spectrometer can detect different isotopes of water and organic molecules contained inside towards detecting the conditions necessary for supporting life. As a first test JPL will be launching the WS-2 mission in June 2023 using a high-altitude balloon and demonstrating these measurements on Earth’s own atmosphere. The FWB4 chip provides the THz signals necessary to drive the WHATSUP instrument, covering the full “W-Band” frequency range from 70-120 GHz which is further multiplied to cover the full 420-720 GHz band.

To protect the microchip, they’re typically encapsulated in a supporting case called a package. Given the extreme performance requirements of this mission, JPL needed an architecture where the chip’s die is mounted directly to the board before being wire bonded to avoid parasitic loss from the package. Second Order Effects (SOE) has a long history of working on aerospace projects that require high-effiency bare die bonding, and began working on JPL on this project. In less than two months, SOE designed a circuit board with a custom bare die footprint and 20 GHz RF layout that can operate at low temperatures and high altitudes.

NASA’s Jet Propulsion Laboratory is a research, development, and flight center, operated by Caltech.