CIRCUIT AND METHOD FOR CONTROL OF COUNTER START TIME
First Claim
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1. An analog to digital conversion (ADC) circuit, comprising:
- a ramp circuit coupled to output a ramp signal, wherein the ramp signal is offset from a starting voltage by an offset voltage, and wherein the ramp signal ramps towards the starting voltage;
a counter circuit coupled to the ramp circuit to start counting after the ramp signal returns to the starting voltage; and
a comparator coupled to the counter circuit and a bitline to compare the ramp signal to a pixel signal voltage on the bitline, and in response to the ramp signal equaling the pixel signal voltage, stop the counter.
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Abstract
An analog to digital conversion (ADC) circuit includes a ramp circuit coupled to output a ramp signal, and the ramp signal is offset from a starting voltage by an offset voltage. The ramp signal ramps towards the starting voltage. A counter circuit is coupled to the ramp circuit to start counting after the ramp signal returns to the starting voltage, and a comparator is coupled to the counter circuit and a bitline to compare the ramp signal to a pixel signal voltage on the bitline. In response to the ramp signal equaling the pixel signal voltage, the comparator stops the counter.
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Citations
20 Claims
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1. An analog to digital conversion (ADC) circuit, comprising:
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a ramp circuit coupled to output a ramp signal, wherein the ramp signal is offset from a starting voltage by an offset voltage, and wherein the ramp signal ramps towards the starting voltage; a counter circuit coupled to the ramp circuit to start counting after the ramp signal returns to the starting voltage; and a comparator coupled to the counter circuit and a bitline to compare the ramp signal to a pixel signal voltage on the bitline, and in response to the ramp signal equaling the pixel signal voltage, stop the counter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of analog to digital conversion, comprising:
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offsetting a ramp signal from a starting voltage by an offset voltage; ramping, with a ramp circuit, the ramp signal towards the starting voltage; starting a counter after the ramp signal returns to the starting voltage; comparing the ramp signal to a pixel signal voltage using a comparator coupled to the ramp circuit; and in response to the ramp signal equaling the pixel signal voltage, stopping the counter. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification