Amplified Charge Cancellation Circuit for Touch Baseline Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional charge compensation circuits in touch sensing systems require large silicon area and high driving capability to handle large baseline signals, which can lead to non-optimal resolution, accuracy, and linearity due to the dominance of baseline signals over induced signals.
Innovation Solution
An amplified charge compensation circuit that uses a programmable current conveyor to inject an amplified cancellation charge, reducing the need for a large capacitor and minimizing the impact of baseline signals, thereby improving charge compensation efficiency and reducing silicon real estate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional charge compensation circuits are used, then charge cancellation is achieved, but large silicon area and high driving capability are required
Solution Approach 1:
The patent changes the gain parameter of the cancellation charge through a programmable gain amplifier. By adjusting the gain parameter, the system can achieve effective charge cancellation with a smaller capacitor size, thereby reducing silicon area while maintaining measurement precision
Solution Approach 2:
The patent introduces a programmable gain amplifier that can dynamically adjust the cancellation charge magnitude. This dynamic adjustment capability allows the system to optimize between charge cancellation accuracy and silicon area usage based on different operating conditions
2Measurement precision
If conventional charge compensation circuits are used, then charge cancellation is achieved, but resolution and accuracy are degraded due to dominance of baseline signals
Solution Approach 1:
The patent uses programmable gain adjustment to precisely control the cancellation charge magnitude. This allows the system to cancel baseline signals effectively while preserving the weaker induced signals, preventing information loss and maintaining high measurement precision
Solution Approach 2:
The system measures the actual baseline signal and uses feedback to adjust the cancellation charge through the programmable gain amplifier. This feedback mechanism ensures accurate cancellation of baseline signals while minimizing impact on induced signal detection
3Power
If conventional charge compensation circuits are used, then baseline signal handling is achieved, but strong driving currents are required
Solution Approach 1:
The patent changes the operational parameters by using a programmable gain amplifier instead of relying solely on large capacitor discharge. This allows effective charge compensation with reduced driving current requirements while maintaining or improving compensation efficiency
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
The solution effectively cancels baseline signals, allowing for precise measurement of induced capacitance without the need for strong driving currents, enhancing the resolution and accuracy of touch sensing systems while being more cost-effective in terms of silicon usage.
Implementation Method 1
a current conveyor having a programmable gain, the current conveyor arranged to amplify an initial charge generated by the capacitor in response to the pulsed voltage signal and provide an amplified charge to an output of the charge cancellation circuit
Data Source
AI summary
A charge compensation circuit is disclosed that provides amplified charge cancellation. A touch controller is disclosed that includes such a charge compensation circuit and may realize improved immunity to baseline capacitance signals that are much larger than a change in capacitance due to proximity of an object. Such a charge compensation circuit may include a capacitor, a driver circuit arranged to apply a pulsed voltage signal to the capacitor, and a current conveyor having a programmable gain and arranged to amplify an initial charge generated by the capacitor in response to the pulsed voltage signal and provide an amplified charge to an output of the charge cancellation circuit.