Sensing Device Gain Control via Segmented Capacitor
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Solution Overview
Problem
In large-sized and high-resolution image sensor applications, the output signal from the amplifier often exceeds the linear operation range due to the need for increased data capacitors, leading to inefficiencies in signal processing.
Innovation Solution
A sensing device is designed with an additional capacitor electrically connected to the data line, allowing for control of the readout circuit's gain by adjusting the ratio of the first capacitor to the feedback capacitor, thereby maintaining linear response even with high parasitic capacitance at the data line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the data capacitor is increased for large-sized and high resolution applications, then the signal capacity is improved, but the output signal exceeds the linear operation range of the amplifier
Solution Approach 1:
The patent divides the data capacitor into two separate capacitors: the original data capacitor and an additional capacitor. This segmentation allows independent control of each capacitor's contribution to the total capacitance, enabling the data capacitor to be increased for high resolution while the additional capacitor compensates to maintain linear operation range.
Solution Approach 2:
The patent introduces dynamic control through switches that can connect or disconnect the additional capacitor based on operating conditions. This dynamic configuration allows the system to adapt the total capacitance value, maintaining linear operation range while supporting high resolution requirements.
2Measurement precision
If the data capacitor is increased to support high resolution, then the resolution capability is improved, but the gain control of the readout circuit becomes difficult
Solution Approach 1:
By segmenting the data capacitor into two independent capacitors, the patent enables separate control of their respective capacitances. This allows the data capacitor to be optimized for high resolution while the additional capacitor is used to adjust and control the gain of the readout circuit independently.
Solution Approach 2:
The patent changes the electrical parameters by introducing an additional capacitor with controllable capacitance value. This provides an extra degree of freedom for adjusting the gain parameter of the readout circuit without affecting the resolution capability determined by the data capacitor.
3Ease of operation
If the additional capacitor is added to control gain, then the gain control is improved, but the device complexity increases
Solution Approach 1:
The patent merges the additional capacitor with the existing data line and readout circuit structure. The additional capacitor is electrically connected in parallel with the data capacitor, sharing common nodes and control mechanisms, which minimizes the increase in device complexity while achieving improved gain control.
Solution Approach 2:
The additional capacitor serves multiple functions: it controls the gain of the readout circuit, compensates for the effects of increased data capacitor capacitance, and maintains linear operation range. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
Data Source
AI summary
A sensing device provided herein includes a first pixel circuit, a readout circuit, a first switch, a second switch, and a first capacitor. The readout circuit is electrically connected to the first pixel circuit. The first switch is electrically connected between the first pixel circuit and the readout circuit. The second switch is electrically connected between the first switch and the readout circuit. The first capacitor includes a first electrode electrically connected to the first switch and the second switch.