A Study on High-Sensitivity Image Sensors Using Signal Processing Techniques for Noise Reduction

点击翻译按钮获取中文摘要

In this, study, new noise reduction techniques based on oversampled signal processing for high-sensitivity image sensors have been investigated. The proposed technique does not require any photo charge multiplication, which is a major technique for highly sensitive imaging. One of the methods uses a multiple sampling of the image array output in non-destructive readout modes. This technique predicts the signal component based on the correlation in the intermediate signal levels in the non-destructive mode of pixel outputs and greatly reduces the output random noise. Another method uses a gain-adaptive amplifier array integrated at the column of the image sensors. An experimental image sensor chip based on 0.25um technology has been developed and the lowest noise level of 260uV in CMOS image sensors is achieved. In order to investigate the low-noise sensor interface, establishment of a noise analysis method for CMOS image sensor interface circuits is indispensable. We have established a noise analysis method for high-gain switched capacitor amplifiers suitable for integrating them at the column of the image sensors. The noise analysis model includes both the thermal and 1/f noises. The analysis shows that a double stage noise-canceling amplifier has extremely low noise level if a noise component sampled at the inside node of the amplifier is cancelled.