An Autonomous micro-Digital Sun Sensor Implemented with a CMOS Image Sensor Achieving 0.004o Resolution @ 21mW

The micro-Digital Sun Sensor (μDSS) is a sun detector which senses a satellite’s instant attitude by detecting its attitude angle with respect to the sun. It is composed of a solar cell power supply, a RF communication block and an imaging chip, which is called APS+. The APS+ integrates a CMOS Active Pixel Sensor (APS) of 368×368 pixels, a 12 bit Analogue to Digital Converter (ADC), and digital signal processing circuits. This paper describes the implementation of a prototype of the μDSS APS+ fabricated in a standard 0.18μm CMOS process. The APS+ is particularly characterized by its low power consumption (a factor 10 lower compared to the state-of-the-art) since power is a critical specification for space application. The power is mainly reduced by “profiling” and “windowing”, which are enabled by a specific active-pixel design. The measurement results are discussed following in this paper.