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US 9,040,889 B2Granted
Analog-to-digital converter with programmable ramp generator
AssigneeUniversity of Idaho
InventorSuat Utku Ay
Life of this patent
Estimating the term…
Abstract
An analog-to-digital (ADC) converter is disclosed that uses aspects of a single-slope ramp ADC, but with jump steps in the ramp voltage to increase speed. A programmable ramp generator can be used to dynamically modify a voltage level associated with the jump step. By programming a voltage level of the jump, a user can dynamically modify the speed of the ADC during operation.
Claims22
An analog-to-digital converter, comprising:
- a programmable ramp generator for providing a substantially ramped output voltage that increases at a first trajectory and for receiving input that allows for a jump step in voltage to move the ramped output to a second trajectory, wherein an amount of the jump step is dynamically programmable;
- a plurality of comparators, each having a first input coupled to the ramp generator, a second input coupled to a respective analog input voltage to be converted to digital, and a respective comparator output;
- a plurality of latches coupled to the comparator outputs;
- and
- a counter coupled to the latches for latching a counter count in response to the comparator outputs.
2 more elements
A method of converting a plurality of analog input signals to digital in an image sensor, comprising:
- receiving programming inputs to a programmable ramp generator in order to set a jump step voltage;
- ramping a voltage level that is input to a comparator at a substantially constant rate;
- jump stepping the ramping voltage level from a first voltage level corresponding to the substantially constant rate to a second voltage level that does not correspond to the substantially constant rate;
- and
- continuing the ramping from the second voltage level, an amount of jump stepping corresponding to the programming inputs in order to speed the conversion of analog input signals to digital.
2 more elements
An image sensor, comprising:
- a pixel array having multiple row selectors with multiple output columns;
- an analog-to-digital converter comprising the following:
- a) a plurality of comparators coupled in parallel having a first input coupled to a ramping voltage signal line and a second input coupled to the multiple columns in a one-to-one relationship;
- b) a plurality of latches coupled to the comparators in a one-to-one relationship, the comparators coupled to a control line of the latch;
- c) a plurality of predictor circuits coupled between the plurality of latches and the plurality of comparators;
- d) a look-ahead controller having an input signal line coupled to the plurality of predictor circuits for generating a signal indicating that a jump step in voltage should occur;
- e) a programmable ramp generator coupled to the look-ahead controller and responsive to the signal indicating that a jump step should occur, the programmable ramp generator having an input port for receiving input controlling an amount of voltage level increase associated with the jump step;
- and
- f) a counter coupled in parallel to the plurality of latches for providing a digital value of the analog signal, which is latched in response to a change in the control line of the latch, the counter further coupled to the look-ahead controller.
6 more elements
Dependencies are inferred from the claim text.