Development and performance evaluation of low-noise CMOS sensor electronics for mission Earth 2.0

The Earth 2.0 (ET) mission aims to discover Earth-like planets by deploying six transit telescopes and one microlensing telescope as its payload. High-performance CMOS sensors have been chosen as the primary imaging solution, necessitating the development of a specialized CMOS camera system. Extensive research and development efforts have focused on CMOS sensors, particularly the 9K × 9K CMOS sensor (Gsense1081BSI) designated for the telescopes. This study presents the design of the camera electronics system tailored for this sensor, including a low-noise secondary power supply, a dedicated CMOS driver module, and an FPGA-based timing control board. The electronics system exhibits low-noise performance and high gain stability. Its low readout noise primarily results from the sensor's carefully regulated low-noise power supply and bias conditions, whereas gain stability is predominantly influenced by the overall stability of the electronics circuitry. Detailed sensor performance evaluation methods and results are presented, covering essential performance parameters such as readout noise, gain, dark current, full well capacity, and linearity. Under vacuum conditions at a temperature of −40 °C, the sensor demonstrated a consistently low readout noise level of 4.6 e- and a stable gain of 1.46 ± 0.08 DN/e- . Furthermore, a series of six consecutive stability tests verified the repeatability and reliability of both gain and readout noise metrics. Overall, the test results indicate that the 9K × 9K CMOS sensor, integrated with the proposed electronics system, fulfills the demanding specifications of the ET mission and is fully capable of supporting Earth 2.0 detection.