Inverting Amplifier Feedback Capacitance Control
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Solution Overview
Problem
The increasing number of pixels and frame rate in image pickup devices lead to higher power consumption due to frequent charging and discharging of the inverting amplifier's feedback capacitance, which is not efficiently managed in existing technologies.
Innovation Solution
The implementation of a semiconductor device with an inverting amplification circuit that disconnects the feedback capacitance from the output during a charge recovery period, allowing it to be connected back to the vertical signal line only between the amplification of an image pickup signal from one pixel and the dark level signal from another, reducing unnecessary power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the feedback capacitance is continuously connected to the output of the inverting amplifier for signal amplification, then the amplification function is maintained, but the power consumption increases due to frequent charging and discharging
Solution Approach 1:
The feedback capacitance is periodically connected and disconnected based on the readout phase. During the signal readout phase, the feedback capacitance is connected to enable amplification. During the dark-level readout phase, the feedback capacitance is disconnected to prevent unnecessary charging and discharging, thereby reducing power consumption while maintaining amplification functionality when needed.
Solution Approach 2:
The connection state of the feedback capacitance is dynamically changed based on the readout requirements. The system transitions between connected and disconnected states of the feedback capacitance according to whether signal amplification is currently needed, optimizing the balance between maintaining amplification function and reducing power consumption.
2Productivity
If the number of pixels and frame rate are increased to improve image quality and speed, then the performance is enhanced, but the power consumption increases due to more frequent charging and discharging cycles
Solution Approach 1:
By implementing periodic connection and disconnection of the feedback capacitance synchronized with the pixel readout cycle, the system handles increased pixel counts and frame rates without proportionally increasing power consumption. The feedback capacitance is only active during necessary amplification periods rather than continuously operating.
3Reliability
If the feedback capacitance remains connected during dark-level readout, then the circuit remains in amplification mode, but unnecessary charging and discharging occurs increasing power consumption
Solution Approach 1:
The system dynamically adjusts the feedback capacitance connection state based on operational requirements. During dark-level readout operations, the feedback capacitance is disconnected to eliminate unnecessary energy consumption, while the system maintains the capability to quickly reconnect when amplification is needed again.
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
This approach significantly reduces electric power consumption by minimizing the frequency of charging and discharging, thereby enhancing the efficiency of charge recovery and lowering overall power consumption, especially as pixel counts and frame rates increase.
Implementation Method 1
an inverting amplification circuit configured to amplify a signal level obtained through the vertical signal line with an amplification factor determined according to a capacitance ratio between an input capacity and a feedback capacity
Implementation Method 2
the feedback capacity is disconnected from an output of the inverting amplification circuit and connected to the vertical signal line in a charge recovery period set in a period between a first timing and a second timing
Data Source
AI summary
In a related-art image pickup device, there is a problem that the power consumption increases. A semiconductor device includes a plurality of pixel circuits connected to one vertical signal line SL, and an inverting amplification circuit configured to amplify a signal level obtained through the vertical signal line SL with an amplification factor determined according to a capacitance ratio between an input capacitor Ci and a feedback capacitor Cf, in which the feedback capacitor Cf is disconnected from an output of the inverting amplification circuit and connected to the vertical signal line SL in a charge recovery period set in a period between a first timing and a second timing, the first timing being a timing when amplification of an image pickup signal read from a first pixel circuit by the inverting amplification circuit has been completed, the second timing being a timing when amplification of a dark level signal read from a second pixel circuit by the inverting amplification circuit is started.