A High Precision Programmable Reference Generator for Monolithic Active Pixel Sensor Using 3D Integrated Technology

Abstract

Monolithic active pixel sensors (MAPS) are promoted to high performance on particle tracking in high energy physics experiment by using three-dimensional integrated technology (3DIT). During the development of MAPS architectures from 2D to 3D, the discriminators for digitizing the detected signal are moved from column level to pixel level. The programmable reference generator (PRG) providing the threshold voltage for the discriminators needs drive load capacitance varying from hundreds of Pico farads to tens of nanofarads. In addition, high precision is still required for evaluating the noise and detection efficiency. This paper presents a design of a 10-bit PRG for 3D MAPS. The architecture of a voltage-scaling network combined with a voltage reference is proposed in order to obtain good stability in a large range of the load capacitance. A resistor-scaling network and a band gap voltage reference are carefully designed due to the absence of output operational amplifier. The proposed PRG is implemented in a 0.13 µm process. The simulation results indicate that the proposed PRG performs good differential non-linearity (INL) and integrated non-linearity (DNL), and the equivalent output noise is less than 200 µV. The voltage resolution of the PRG is about 500 µV. The PSSR of the PRG is about-65 DB in low frequency and is lower than-43 DB during the whole frequency domain. In addition, the PRG performs good tolerance to the variation of temperature and power supply voltage. Therefore, the PRG in this work is suitable for 3D MAPS and the other applications that require high precision and low noise with large load capacitance but ignorable load current.