Image sensor with s/h-to-adc voltage range matching

A method of operating an image sensor that comprises a plurality of image pixel circuits arranged in an array, image processing circuitry including a sample-and-hold circuit and an analog-to-digital converter, and a reference adjustment circuit, the method comprising:

• receiving, by the sample-and-hold circuit, a first reference voltage;
• receiving, by the analog-to-digital converter, a second reference voltage;
• and
• selectively adjusting, by the reference adjustment circuit, the first reference voltage and/or the second reference voltage, thereby to match an operating range of the sample-and-hold circuit with an operating range of the analog-to-digital converter, based on a measurement signal.

An image sensor, comprising:

• a plurality of image pixel circuits arranged in a first array having M rows and N1 columns, wherein M and N1 are positive integers;
• a plurality of dummy pixel circuits arranged in a second array having M rows and N2 columns, wherein N2 is a positive integer;
• image processing circuitry including a sample-and-hold circuit configured to receive a first reference voltage and an analog-to-digital converter configured to receive a second reference voltage;
• and
• a reference adjustment circuit configured to selectively adjust the first reference voltage and/or the second reference voltage, thereby to match an operating range of the sample-and-hold circuit with an operating range of the analog-to-digital converter, based on a measurement signal.