MOSCAP Passive Amplifier Using Sample-and-Hold Voltage Gain
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Solution Overview
Problem
Modern image sensors face inefficiencies and noise issues due to the use of active column amplifiers, which have high bias currents, consume excessive power, and are less accurate, making it challenging to design effective column sensing circuitry.
Innovation Solution
Implementing a passive amplifier circuit using metal-oxide-semiconductor capacitors (MOSCAPs) that provide voltage gain through a sample-and-hold mechanism, reducing noise and power consumption while maintaining high speed and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If active column amplifiers are used, then signal amplification is achieved, but power consumption increases and noise is generated
Solution Approach 1:
The patent inverts the conventional active amplifier approach by using a passive amplifier circuit. Instead of using an active device (transistor) to amplify the signal, the patent uses a passive RC circuit where the signal is amplified through the interaction of the signal charge itself with the circuit components, eliminating the need for high bias current and thus reducing power consumption while maintaining amplification capability.
2Power
If active column amplifiers are used, then signal amplification is achieved, but noise levels increase
Solution Approach 1:
The patent eliminates active devices that generate noise by using a passive amplifier circuit. The amplification is achieved through the passive interaction of the signal charge with the RC circuit components, which do not introduce the thermal noise and other harmful emissions associated with active transistor operation, thus reducing noise levels while maintaining amplification.
3Use of energy by moving object
If passive amplifier circuit is used, then power consumption is reduced, but bandwidth limitations may occur
Solution Approach 1:
The patent optimizes the bandwidth of the passive amplifier by carefully selecting and adjusting the values of the capacitor and resistor components. By changing the capacitance value and resistance value parameters, the circuit achieves a bandwidth sufficient for image sensor applications while maintaining the low power consumption advantage of passive operation. The capacitor is specifically sized to work with the signal charge from the pixel, and the resistor is selected to provide appropriate time constants for the desired bandwidth.
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 MOSCAP-based passive amplifier achieves low noise, low power consumption, and high-speed signal amplification without bandwidth limitations, improving the performance of image sensors.
Implementation Method 1
a metal-oxide-semiconductor capacitor having a gate terminal configured to receive a control signal and source-drain terminals coupled to the output port
Data Source
AI summary
A passive amplifier is provided that includes an input sampling switch, a sampling capacitance, and metal-oxide-semiconductor capacitor devices. An input signal may be sampled onto the sampling capacitance by turning on the input sampling switch while the metal-oxide-semiconductor capacitors are activated. After the sampling phase, the metal-oxide-semiconductor capacitors are deactivated to provide a voltage gain. The voltage gain can be conditionally applied depending on the signal level of the sampled input.