Reference voltage stabilization in CMOS sensors
AssigneeMicron Technology, Inc.
InventorsSteve Huang, Daniel Van Blerkom, Sandor L. Barna, Giuseppe Rossi
Life of this patent
Estimating the term…
Abstract
A reference voltage generator for use in an image sensor provides a reference voltage to an S/H block during a pixel read-out operation and another reference voltage to an analog-to-digital converter (ADC) during a digitization operation. The reference voltage generator includes a variable voltage generator, a sample-and-hold circuit to sample a reference voltage prior to the pixel read-out operation or the digitization operation, and a buffer amplifier to drive the appropriate reference voltage to the relatively high impedance load presented by the S/H block and the variable impedance load provided by the ADC.
Claims22
A method comprising:
- generating a reference voltage;
- sampling the reference voltage;
- and
- driving the sampled reference voltage to a load in a pixel read-out chain with a buffer amplifier.
Apparatus comprising:
- a voltage generator operative to generate a first reference voltage for a pixel read-out operation and to generate a second reference voltage for an analog-to-digital conversion operation;
- a sample-and-hold circuit coupled to the voltage generator and operative to sample-and-hold the first reference voltage prior to the pixel read-out operation and to sample and hold the second reference voltage prior to the analog-to-digital conversion operation;
- and
- a buffer amplifier coupled to the sample-and-hold circuit and operative to amplify a sampled reference voltage.
A sensor comprising:
- a pixel array including a plurality of pixels;
- a sample-and-hold block operative to receive signals from the pixel array, said sample-and-hold block including a plurality of capacitors and a plurality of switches operatively coupling said plurality of capacitors to a first reference voltage;
- an analog-to-digital converter (ADC) operative to receive signals from said sample-and-hold block, said ADC including a plurality of capacitors and a plurality of switches, operatively coupling said plurality of capacitors to a second reference voltage;
- and
- a voltage generator operative to generate the first reference voltage and the second reference voltage, said voltage generator including
- a sample-and-hold circuit operative to sample-and-hold the first reference voltage prior to a pixel read-out operation and to sample and hold the second reference voltage prior to an analog-to-digital conversion operation;
- and
- a buffer amplifier coupled to the sample-and-hold circuit and operative to amplify a sampled reference voltage.
Dependencies are inferred from the claim text.