Image Sensor Pulse Generator Stabilization Circuit
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Solution Overview
Problem
Image sensors face challenges in reducing power consumption and noise generation due to variations in power voltage, which affect the accuracy and reliability of pulse generation, especially when using typical pulse generators that are not designed to handle changes in power states effectively.
Innovation Solution
A pulse generator for image sensors is designed with a delay cell comprising transistors arranged in series, stabilization capacitors, and switches, which maintains a constant voltage across the transistors, reducing noise and power consumption by stabilizing the power supply ripple rejection and minimizing the impact of power voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a typical pulse generator method is used to reduce power consumption during counter counting period, then power consumption is reduced, but excessive noise is generated due to pulse width variation when power voltage changes
Solution Approach 1:
The patent applies parameter changes by introducing a stabilization capacitor connected to the gate terminal of the first transistor and a stabilization switch that supplies a reference voltage to maintain the gate-source voltage constant. This compensates for power voltage variations, keeping the pulse width stable while enabling power consumption reduction during counter counting period.
2Speed
If the ADC operates at higher speeds to handle large number of pixels, then processing speed is improved, but power consumption increases in proportion to the frequency of the counter
Solution Approach 1:
The patent implements periodic action by controlling the stabilization switch to operate only during specific periods: turning on during reset period to charge the stabilization capacitor, and turning off during counter counting period. This periodic operation enables power consumption reduction while maintaining pulse stability when needed.
3Device complexity
If a delay cell is designed without stabilization components, then device complexity is reduced, but the delay cell is affected by power state changes causing noise and inaccuracies
Solution Approach 1:
The patent introduces a stabilization capacitor and stabilization switch as intermediary components between the power voltage source and the delay cell's gate terminal. These intermediaries filter and stabilize the voltage supplied to the transistor, isolating the delay cell from power state changes while maintaining minimal added complexity.
Data Source
AI summary
A pulse generator of an image sensor includes a delay cell including a plurality of transistors arranged in series between a power voltage and a ground, a stabilization capacitor, and a stabilization switch. The power voltage is supplied to a first terminal of a first transistor disposed first among the plurality of transistors, and a gate terminal of the first transistor is connected to a first node. An input voltage is supplied to a gate terminal of an n-th transistor disposed last among the plurality of transistors, and a ground voltage is supplied to a first terminal of the n-th transistor. The stabilization switch is disposed between a reference voltage input terminal providing a reference voltage and the first node. The stabilization switch is turned on by an input bias control signal to supply the reference voltage to the first node.