Analog Devices,inc.

Analog Devices International Unlimited Company

Analog Devices Global Unlimited Company

Edward Chapin Guthrie

Jonathan Ephraim David Hurwitz

Michael C W Coln

Junhua Shen

Baozhen Chen

Mark D Maddox

Daniel Peter Canniff

Abhishek Bandyopadhyay

Ronald Alan Kapusta

Steven J Decker

Katsu Nakamura

Mariana Tosheva Markova

Joseph Leandro Balais Peje

Masatoshi Sase

The present disclosure relates to imaging systems having functionality for detecting faults in the control and/or readout of the image sensor. In one example, there is a system comprising an image sensor having a plurality of imaging pixels and at least one diagnostic pixel coupled to a reference signal. The system also comprises control and readout circuitry configured to select one or more of the imaging pixels and, for each selected imaging pixel, readout an imaging signal that is indicative of the charge accumulated on the selected imaging pixel, select the at least one diagnostic pixel and, for each selected diagnostic pixel, readout a diagnostic signal that is indicative of the reference signal of the selected diagnostic pixel, and output the diagnostic signal for use in system diagnostics.

Image sensor

An ADC circuit that can resolve the most significant bits (MSBs) using a first circuit during a first stage of a multi-stage conversion and resolve the least significant bits (LSBs) using a second circuit during a second stage of the multi-stage conversion. This can be used, for example, in massively parallel applications where the reference level generation can be shared between thousands of converters.

Multi-stage conversion analog-to-digital converter

Embodiments of the present disclosure provide ADCs particularly suitable for PDAF image sensors, which ADCs may have an increased speed and/or reduced design complexity and power consumption compared to conventional implementations. An example ADC for a PDAF image sensor is configured to implement modified SAR techniques which reduce the number of bit trials required for conversion, and enable increased number of samples in a row-conversion time period of the image sensor. The ADC may implement the modified SAR techniques in combination with CMS in pixel readout signal chain, which may reduce noise without a proportionate increase in ADC sample rate.

Analog-to-digital converters for phase-detection autofocus image sensors

A multibit flash quantizer circuit, such as included as a portion of delta-sigma conversion circuit, can be operated in a dynamic or configurable manner. Information indicative of at least one of an ADC input slew rate or a prior quantizer output code can be used to establish a flash quantizer conversion window. Within the selected conversion window, comparators in the quantizer circuit can be made active. Comparators outside the conversion window can be made dormant, such as depowered or biased to save power. An output from such dormant converters can be preloaded and latched. In this manner, full resolution is available without requiring that all comparator circuits within the quantizer remain active at all times.

Power-efficient flash quantizer for delta sigma converter

During operation of a SAR ADC, several of the MSBs can be preloaded with predetermined bit decisions prior to carrying out bit trials. A system and method can be provided for incrementally preloading the predetermined bit decisions such as to maintain voltages present at comparator inputs within a limited range of acceptable input voltages.

Incremental preloading in an analog-to-digital converter

An analog-to-digital converter (ADC) circuit comprises a digital-to-analog (DAC) circuit including at least N+n weighted circuit components, wherein N and n are positive integers greater than zero, and n is a number of repeat bits of the least significant bit (LSB) of the ADC circuit; a sampling circuit configured to sample an input voltage at an input to the ADC circuit and apply a sampled voltage to the weighted circuit components; a comparator circuit configured to compare an output voltage of the DAC to a specified threshold voltage during a bit trial; and logic circuitry configured to perform bit trials for the at least N+n weighted circuit components and adjust one or more parameters for one or more of N bit trials according to values of the n LSB repeat bits.

SAR ADC performance optimization with dynamic bit trial settings

Embodiments of the present invention may provide an analog-to-digital converter (ADC) system. The ADC system may include an analog circuit to receive an input signal and a reference voltage, and to convert the input signal into a raw digital output. The analog circuit may include at least one sampling element to sample the input signal during a sampling phase and reused to connect to the reference voltage during a conversion phase, and an ADC output to output the raw digital output. The ADC system may also include a digital processor to receive the raw digital output and for each clock cycle, to digitally correct reference voltage errors in the analog-to-digital conversion.

Background calibration of ADC reference voltage due to input signal dependency

Previously available analog domain decimation techniques are limited to simple equally-weighted averaging of photosite outputs. Decimation of a Bayer pattern image by an even-factor, such as by two or six, using simple equally-weighted averaging of photosite outputs in the analog domain results in effective sampling locations that are unevenly spaced apart. Standard interpolation of the unevenly spaced effective sampling locations generates image artifacts that reduce the quality of the reconstructed image in the smaller format because standard interpolation methods assume that the effective sampling locations are evenly spaced. Implementations of systems, methods and apparatus disclosed herein aim to produce substantially evenly spaced effective sampling locations in the analog domain. More specifically, in some implementations, the unequally-weighted-average even-factor decimation methods disclosed herein produce substantially more evenly spaced effective sampling locations as compared to the equally-weighted-average even-factor decimation processes previously used in the analog domain.

Growing community of inventors

Charlestown, MA, United States of America

Edward Chapin Guthrie