Optical Pulse Detection IC LIDARX Integrated in MMX-LIDAR

LIDARX, an optical pulse detection integrated circuit (IC), has been developed for LIDAR receivers onboard planetary explorers. JAXA developed the IC, based on the experience of the Hayabusa and Hayabusa2 projects, to reduce the circuit size of the receiver, shorten the development period, and improve sensitivity. This IC has been implemented as the core device for the receiver circuit of the LIDAR installed in the explorer of the Japanese Martian Moons eXploration (MMX) mission. The explorer will perform close-up remote sensing and in situ observations of both moons and collect a sample from one of the moons to bring back to Earth. LIDARX is not a simple time-to-digital converter circuit but a sophisticated IC with micro-signal amplification, timing detection, wave height measurement, and clock interpolation functions. Furthermore, LIDARX has a wide dynamic range of 60 dB for light intensity to accommodate distance changes of about three orders of magnitude, which is expected when LIDAR is used as a navigation sensor during landing. The CMOS process is a conventional 0.35 μm, which has been well-tested in high-energy physics, to ensure radiation resistance. This report describes the details, functions, and calibration method of LIDARX’s peripheral circuits and the circuits inside the IC, and evaluates its dynamic range and measurement accuracy. In addition, test results are reported for resistance to single-event effects and total ionization dose, which are essential for onboard spacecraft components.