||In this thesis, a new active pixel architecture is designed using TSMC 0.18μm 1P6M 1.8V mixed signal processing, which is different from linear pixel sensor (3T APS) and logarithmic pixel sensor (Logarithmic Pixel). There are cases where the dynamic range is insufficient under high and low illumination, respectively. The framework proposed in this thesis has a dynamic range of up to 160db, which is much higher than the above two architectures. It can be applied to the high dynamic range CMOS image sensors.|
In terms of circuit design, in order to achieve high dynamic range, this thesis adopts a linear-logarithmic active pixel architecture as the base for improvement. The main purpose is to pass the output value of the source follower back to transistor’s gate, which is in the logarithmic architecture. When the photocurrent is large, the output value of the source follower is lower, thereby increasing the output current of the transistor to delay the voltage drop rate of the sensing terminal of the photodiode and improve the dynamic range of the pixel sensor. In addition, due to the low complexity of the circuit, this architecture also has a higher fill factor (Fill Factor), which can be as high as 55%, which is much better in the conventional high dynamic range sensors.