Differential Amplifier Circuit Slew Rate Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing differential amplifier circuits in imaging devices face challenges in achieving a high slew rate without increasing power consumption, as the current for charging variable capacitors becomes low or zero when fully charged, leading to prolonged discharge times.
Innovation Solution
The implementation of a differential amplifier circuit with a capacitor element connected to both a current source and a voltage supply node, where the capacitor's voltage is reset and then charged as bias current, allowing for controlled high slew rates without increased current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a variable capacitor is connected in parallel with a current source circuit to achieve high slew rate, then the slew rate increases, but the current consumption increases
Solution Approach 1:
The patent applies dynamics by making the capacitor configuration adjustable through switches. The first switch connects the capacitor to the current source circuit during the charging phase to achieve high slew rate, while the second switch connects the capacitor to the voltage supply node during the discharge phase. This dynamic switching allows the system to optimize performance at different operational stages without continuously consuming high current.
Solution Approach 2:
The patent implements periodic action through the alternating connection of the capacitor to different circuits via switches. The capacitor is periodically connected to the current source circuit for charging and to the voltage supply node for discharge. This periodic switching enables the system to achieve high slew rate only when needed (during charging) while reducing current consumption during the discharge phase, rather than maintaining high current continuously.
2Quantity of substance
If the variable capacitor is fully charged, then the charging current becomes low or zero, but the discharge time becomes prolonged
Solution Approach 1:
The patent extracts the discharge function from the current source circuit by providing a separate voltage supply node connected through a second switch. When the capacitor is fully charged and the charging current becomes low or zero, the second switch connects the capacitor to the voltage supply node, creating a dedicated discharge path. This separation allows the capacitor to discharge quickly through the voltage supply node rather than relying on the current source circuit, thereby reducing discharge time without affecting the charging current quantity.
3Speed
If the capacitor voltage is reset and charged as bias current, then the slew rate increases with faster response times, but the switch control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-connecting the capacitor to the voltage supply node through the second switch before the charging process begins. This preliminary connection establishes the discharge path in advance, so that when the capacitor becomes fully charged and needs to be reset, the discharge mechanism is already in place and can immediately activate, reducing the response time without adding complex control logic during the charging phase.
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 configuration enables a higher slew rate with faster response times in the amplification circuit while maintaining low power consumption by managing the capacitor's charging and discharging through switch control, enhancing the imaging device's performance.
Implementation Method 1
a capacitor element (207) having a first terminal (TA) and a second terminal (TB)
Data Source
AI summary
An imaging device according to an exemplary embodiment includes a plurality of pixels, a differential amplifier circuit that includes a plurality of transistors forming a differential pair, and a current source configured to supply a bias current to the plurality of transistors, and is configured to receive a signal from the plurality of pixels, a capacitor element including a first terminal and a second terminal, a first switch through which the first terminal is connected to an electric path between the current source and the plurality of transistors, and a second switch through which the first terminal is connected to a voltage supply node supplied with a voltage.