1/f Noise Modelling and Characterization for CMOS Quanta Image Sensors

Wei Deng,Eric R Fossum

doi:10.3390/s19245459

Abstract

This work fits the measured in-pixel source-follower noise in a CMOS Quanta Image Sensor (QIS) prototype chip using physics-based 1/f noise models, rather than the widely-used fitting model for analog designers. This paper discusses the different origins of 1/f noise in QIS devices and includes correlated double sampling (CDS). The modelling results based on the Hooge mobility fluctuation, which uses one adjustable parameter, match the experimental measurements, including the variation in noise from room temperature to –70 °C. This work provides useful information for the implementation of QIS in scientific applications and suggests that even lower read noise is attainable by further cooling and may be applicable to other CMOS analog circuits and CMOS image sensors.

Highlights

The Quanta Image Sensor (QIS) was proposed in 2005 [1] as a possible next-generation solid-state image sensor after charge-coupled devices (CCDs) and CMOS image sensors (CIS)
We find that the mobility fluctuation-based model fits the best
Hooge mobility fluctuation model seems to provide a good fit for all parameters under investigation in contrast to earlier modelling results we reported that favored the modified Berkeley model [15]

Summary

Introduction

The Quanta Image Sensor (QIS) was proposed in 2005 [1] as a possible next-generation solid-state image sensor after charge-coupled devices (CCDs) and CMOS image sensors (CIS). QIS features high temporal-spatial resolution and has a deep sub-electron read noise that allows photon counting. The QIS read noise target is below 0.15 e− rms [2] single electron quantization becomes apparent below about 0.45 e− rms. QIS achieving room-temperature single-photon discrimination without avalanche gain with average read noise of 0.21 e− rms [3]. In CCDs, CIS, and CMOS QIS, the signal sense node (the floating diffusion, “FD”) is connected to the gate of a source-follower amplifier. It is believed that noise from the in-pixel source-follower (SF) transistor dominates the read noise of QIS and high-sensitivity CIS. The origin of RTN is usually attributed to conduction carrier trapping and re-emission at the Si-SiO2 interface, while the theory of thermal noise is well-established. The physical origin of 1/f noise has not been well established

Methods

Discussion

Conclusion