An Implantable CMOS Image Sensor With Self-Reset Pixels for Functional Brain Imaging

Sasagawa, Kiyotaka; Yamaguchi, Takahiro; Haruta, Makito; Sunaga, Yoshinori; Takehara, Hironari; Takehara, Hiroaki; Noda, Toshihiko; Tokuda, Takashi

doi:10.1109/ted.2015.2454435

Cited by 35 publications

(35 citation statements)

References 21 publications

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“…This feature is not only critical to consumer photography [29] but also plays an important role in life sciences and bio-imaging. For instance, last year, Sasagawa [30] and Yamaguchi [31] developed SR-ADCs for functional brain imaging.…”

Section: B a Solution Via Modularmentioning

confidence: 99%

“…In comparison to the remarkable progress that has been made on the hardware front of the new ADCs, theoretical and algorithmic aspects related to the identifiability and recovery properties of the modulo samples remain largely unexplored. Namely, all previous approaches [28], [30], [31] would require additional information such as a detailed account of how often the amplitudes have been folded (cf. Fig.…”

Section: B a Solution Via Modularmentioning

confidence: 99%

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On unlimited sampling

Bhandari

Krahmer

Raskar

2017

2017 International Conference on Sampling Theory and Applications (SampTA)

158

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Shannon's sampling theorem provides a link between the continuous and the discrete realms stating that bandlimited signals are uniquely determined by its values on a discrete set. This theorem is realized in practice using so called analog-to-digital converters (ADCs). Unlike Shannon's sampling theorem, the ADCs are limited in dynamic range. Whenever a signal exceeds some preset threshold, the ADC saturates, resulting in aliasing due to clipping. The goal of this paper is to analyze an alternative approach that does not suffer from these problems. Our work is based on recent developments in ADC design, which allow for ADCs that reset rather than to saturate, thus producing modulo samples. An open problem that remains is: Given such modulo samples of a bandlimited function as well as the dynamic range of the ADC, how can the original signal be recovered and what are the sufficient conditions that guarantee perfect recovery? In this paper, we prove such sufficiency conditions and complement them with a stable recovery algorithm. Our results not limited to certain amplitude ranges, in fact even the same circuit architecture allows for the recovery of arbitrary large amplitudes as long as some estimate of the signal norm is available when recovering. Numerical experiments that corroborate our theory indeed show that it is possible to perfectly recover function that takes values that are orders of magnitude higher than the ADC's threshold.

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Section: B a Solution Via Modularmentioning

confidence: 99%

Section: B a Solution Via Modularmentioning

confidence: 99%

On unlimited sampling

Bhandari

Krahmer

Raskar

2017

2017 International Conference on Sampling Theory and Applications (SampTA)

158

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“…The novelty of this image sensor over previous ones based on self-reset operation [22], [24], [25] is that pixels over-flow events are not stored on in-pixel memories. We use AER communication to transmit asynchronously the address of the pixels that overflow every time that this event occurs.…”

Section: A Operation Principlementioning

confidence: 99%

“…Fig. 22 Finally, sensors [22], [24], [25] use a self-resetting mechanism like the described in this work.…”

Section: H Event-based Operationmentioning

confidence: 99%

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A Wide Linear Dynamic Range Image Sensor Based on Asynchronous Self-Reset and Tagging of Saturation Events

Leñero‐Bardallo

Carmona-Galán

Rodríguez-Vázquez

2017

IEEE J. Solid-State Circuits

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We report a High Dynamic Range (HDR) image sensor with linear response that overcomes some of the limitations of sensors with pixels with self-reset operation. It operates similarly to an Active Pixel Sensor (APS), but its pixels have a novel asynchronous event-based overflow detection mechanism. Whenever pixels voltage at the integration capacitance reaches a programmable threshold, pixels selfreset and send out asynchronously an event indicating it. At the end of the integration period, the voltage at the integration capacitance is digitized and readout. Combining this information with the number of events fired by each pixel, it is possible to render linear HDR images. Event operation is transparent to the final user. There is not a limitation for the number of self-resets of each pixel. The output data format is compatible with frame-based devices. The sensor was fabricated in the AMS 0.18µm HV technology. A detailed system description and experimental results are provided in the article. The sensor can render images with intra-scene dynamic range up to 130dB with linear outputs. Pixels pitch is 25µm. Sensor power consumption is 58.6mW.

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