Michael Guidash

Hardware validated unified model of multibit temporally and spatially oversampled image sensors with conditional reset

Abstract. We describe a photon statistics-based theoretical model of the response to incident light of an image sensor and show that conditional reset and multibit temporal oversampling increase the dynamic range significantly. This photon-based modeling approach describes the full image sensor design space of temporal and spatial oversampling either with a binary comparison or with a multibit read of each sample. We find excellent quantitative agreement between measurements on custom hardware and our theoretical predictions. We then use this model to show what improvements in dynamic range and low-light response can be achieved by oversampling and what the limits of improvement caused by pixel size and lens parameters are.

Reduction of CMOS Image Sensor Read Noise to Enable Photon Counting.

Recent activity in photon counting CMOS image sensors (CIS) has been directed to reduction of read noise. Many approaches and methods have been reported. This work is focused on providing sub 1 e− read noise by design and operation of the binary and small signal readout of photon counting CIS. Compensation of transfer gate feed-through was used to provide substantially reduced CDS time and source follower (SF) bandwidth. SF read noise was reduced by a factor of 3 with this method. This method can be applied broadly to CIS devices to reduce the read noise for small signals to enable use as a photon counting sensor.

Non-destructive threshold assessment of a pinned photo diode pixel with correlated double sampling

This paper presents a pixel architecture and method of operation that enables a non-destructive assessment of the charge collected in a pinned photo diode pixel with transfer gate. The proposed architecture allows both true correlated double sampling for low noise at low light and per-pixel control of oversampling to increase the dynamic range of small pixels with limited full well capacity.