This thesis deals with the designing of CMOS image sensors with in-pixel analog-to-digital conversion. A 2-stage memory write scheme for Pulse-Width-Modulation digital pixel sensors is proposed. It utilizes the characteristics of Gray-code counters and partitions a single data write operation into two separated write operations such that the size of the in-pixel memory can be significantly reduced. A Pulse-Frequency-Modulation pixel significantly reduces the integration time without sacrificing the dynamic range. Finally, a Pulse-Frequency-Modulation Digital Pixel Sensor with an in-pixel variable reference voltage is proposed.
As compared with conventional Pulse-Frequency-Modulation pixels, the proposed architecture improves the dynamic range by adaptively adjusting the reference voltage in the pixel. All proposed digital pixel sensors are designed in TSMC-0.18μm 6-Metal 1-Poly 1.8 V CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3V3 device models. The effectiveness of the proposed digital pixel sensors is validated using simultation.
CNC constant voltage power is composed by the analog power circuit, MCU control circuit , pulse width modulation circuit, a power driver amplifier , analog to digital conversion circuit , the input voltage setting circuit and the output voltage display circuit. The power possesses the functions of digital regulator, high precision output, short-circuit & over-current protection and alarm functions, especially for a higher accuracy requirements for various occasions.
An array of 128×128 digital pixel sensors (DPS) that performs both in pixel light current integration and analog-to-digital conversion is presented. The pixel fabricated on a DP4M CMOS process provides a digital output of ultraviolet light intensity via an integrated multiple-channel bit-serial (MCBS) ADC. Due to low light current (~pA) of ultraviolet focal-plane-array, the architecture of capacitive trans-impedance amplifier (CTIA) is used. The proposed readout integrated circuits have a 12-bit resolution, 70dB dynamic range and 99% of linearity.
Design of a low-light-level image sensor with on-chip sigma-delta analog-to-digital conversion