Abstract
This thesis describes work undertaken in the Electrical and Electronic Engineering Department at the University of Surrey in conjunction with the Royal Greenwich Observatory and GEC Hirst Research Centre on the noise performance of charge-coupled devices when used for astronomical imaging. Three noise reduction methods, including a novel read-out method not previously utilised, have been investigated using an astronomical imaging system designed and built at the University of Surrey. The CCD chosen as the detector was a GEC P8600, which is commonly used by astronomers and has the lowest noise level of available CCD's. The most important considerations affecting the noise performance of a CCD astronomical imaging system are the output MOSFET charge amplifier, which converts the CCD signal charge (carried as electrons) to an output voltage and the signal processing method utilised. Firstly, the noise and node capacitance of the output MOSFET charge amplifier were investigated and found to vary significantly with operating point. The correlated double sampling signal processing methods employed with CCDs were also investigated and their limitations overcome. Finally, a novel 'off-chip' charge detection amplifier was investigated, producing promising results. It has been concluded that the signal processing methods used are close to optimum and significant reductions in noise can be achieved by optimum biasing of the output MOSFET. However, devices with significantly lower 1/f noise must be fabricated to achieve the ultimate aim of less than a 3 electron noise level. Using the 'off-chip' charge amplifier noise levels around 25 electrons have been achieved, being lower than a number of other CCD devices. Employing this method with other devices would then significantly reduce their noise levels.