Switchable Capacitor Op-Amp for Faster Feedback Charging
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Solution Overview
Problem
Operational amplifiers are limited by the time required for charging or discharging feedback capacitors, which restricts their response speed and overall circuit performance.
Innovation Solution
The operational amplifier incorporates a capacitor selection circuit that selectively couples candidate capacitors to the gain stages based on the input signal magnitude, allowing only part of the capacitors to be used at a time and charging them in groups to reduce charging and discharging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback capacitors are used in operational amplifier, then the operational amplifier can function properly, but the charging and discharging time of capacitors restricts the response speed
Solution Approach 1:
The patent implements dynamic capacitor selection by using a capacitor selection circuit that can dynamically choose different candidate capacitors based on input signal magnitude. The system transitions from a static capacitor configuration to a dynamic one where capacitors are selectively coupled to the second gain stage through switches controlled by the capacitor selection circuit, enabling adaptive response speed optimization.
Solution Approach 2:
The patent changes the operational parameters of capacitors by pre-charging different candidate capacitors to different voltage values (first voltage, second voltage, third voltage) before selecting them for use. This parameter change allows the operational amplifier to quickly respond to different input signal magnitudes without requiring full charging cycles, thereby improving response speed while maintaining proper functionality.
2Speed
If multiple capacitors are used to improve response speed, then charging and discharging time can be reduced, but the device complexity increases
Solution Approach 1:
The patent segments the capacitor system into multiple independent candidate capacitors (first candidate capacitor, second candidate capacitor, third candidate capacitor), each with its own switches and control logic. This segmentation allows the system to manage complexity by dividing the overall capacitor selection task into smaller, independently controllable units, where each capacitor can be selectively activated based on specific conditions.
Solution Approach 2:
The patent creates a universal capacitor selection mechanism that can handle multiple capacitors through a standardized control approach. The capacitor selection circuit uses a consistent methodology to control switches for different capacitors, and the pre-charging mechanism applies universally across all candidate capacitors. This multi-functional design allows the same control logic to manage any number of candidate capacitors, reducing overall system complexity despite the increased number of components.
Data Source
AI summary
An operational amplifier includes: a first gain stage for generating a second signal based on a first signal transmitted from a prior stage circuit; a second gain stage for generating an output signal based on the second signal; multiple candidate capacitors; and a capacitor selection circuit for switching the coupling relationship of the multiple candidate capacitors based on the magnitude of an input signal of the prior stage circuit, so that only a portion of the multiple candidate capacitors could be coupled to the second gain stage at a time.