Data Output Circuit High-Speed Readout CMOS Image Sensors
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Solution Overview
Problem
The increase in column lines in CMOS image sensors leads to a decrease in readout speed due to increased data loading, and amplifying the sense amplifier to improve speed results in higher current consumption.
Innovation Solution
A data output circuit that includes a line memory to latch and amplify digital signals, a precharge circuit to precharge column lines, a charge circuit to charge input nodes of the sense amplifier, and a charge controller to manage precharge voltages, allowing for high-speed data readout while managing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of column lines increases to support higher resolution, then image quality and resolution improve, but readout speed decreases due to increased data loading
Solution Approach 1:
The precharge circuit precharges the column lines to a reference voltage level before the sensing operation begins. This preliminary action prepares the column lines in advance, reducing the time required for signal amplification and enabling faster readout speeds without compromising image quality
Solution Approach 2:
The data output circuit is divided into multiple independent sense amplifiers, each handling a specific column line. This segmentation allows parallel processing of data from multiple column lines simultaneously, thereby maintaining high readout speed even as the total number of column lines increases for higher resolution
2Speed
If the gain of the sense amplifier increases to read out data at a higher speed, then readout speed improves, but current consumption increases
Solution Approach 1:
The precharge circuit changes the voltage parameter of the column lines by precharging them to an optimal reference voltage level. This parameter optimization enables the sense amplifier to operate at lower gain settings while maintaining high readout speed, thereby reducing current consumption
Solution Approach 2:
By precharging the column lines in advance, the circuit reduces the amplification burden on the sense amplifier during the actual sensing operation. This preliminary preparation allows for lower amplifier gain and reduced current consumption while maintaining high readout speed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high-speed data readout in CMOS image sensors by amplifying voltage differences between column lines, thereby increasing operation speed without significantly increasing current consumption.
Implementation Method 1
a precharge circuit coupled to precharge the pair of column lines with a first precharge voltage level in response to a first precharge signal
Implementation Method 2
a sense amplifier in communication with the line memory to amplify the digital signal on the pair of column lines in response to a sensing enable signal
Implementation Method 3
a charge circuit structured to couple the line memory to the sense amplifier and configured to pass the digital signal to the sense amplifier
Data Source
AI summary
Disclosed are devices, systems and methods for reading out data at a high speed. The data output circuit includes a line memory configured to latch a digital signal, and output the latched digital signal to a pair of column lines in response to an output control signal, a precharge circuit configured to precharge the pair of column lines with a first precharge voltage level in response to a first precharge signal, a charge circuit configured to charge the pair of column lines with a voltage, a charge controller configured to charge the charge circuit with a second precharge voltage level in response to a second precharge signal, and a sense amplifier configured to amplify an output voltage of the charge circuit in response to a sensing enable signal.