Touch Integrator Compensation Circuit for Small Current Detection
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Solution Overview
Problem
Existing touch circuits face saturation issues due to excessively large reference currents, which hinder the detection of smaller sensing currents.
Innovation Solution
A touch circuit design that includes an integrator circuit and a compensation circuit, where the compensation circuit generates a compensation current by switching voltages to reduce the reference current, thereby increasing the compensation charge and reducing the required capacitance of the compensation capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large reference current is used in the touch circuit, then the reference current can drive the touch sensor effectively, but the current integrator saturates and cannot detect the smaller sensing current
Solution Approach 1:
The compensation circuit generates a compensation current that opposes and reduces the reference current before it reaches the current integrator. By preliminarily counteracting the excessive reference current, the integrator is prevented from saturating and can accurately detect the sensing current.
Solution Approach 2:
The compensation circuit acts as an intermediary between the reference current source and the current integrator. It introduces a compensation current that mediates the interaction between the large reference current and the sensitive integrator, enabling accurate detection without saturation.
2Quantity of substance
If a compensation voltage with limited amplitude is used to generate compensation current, then the circuit operates within voltage constraints, but a large compensation capacitance is required which increases device complexity
Solution Approach 1:
The patent changes the voltage parameters dynamically by switching between different voltage levels (first voltage level and second voltage level). This parameter change allows the generation of sufficient compensation current with a smaller compensation capacitance, reducing device complexity while maintaining effectiveness.
Solution Approach 2:
The compensation circuit employs periodic switching of voltage levels to generate the compensation current. This periodic action enables the use of smaller capacitance values by repeatedly charging and discharging the compensation capacitor, thereby reducing overall device complexity.
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 reduces the capacitance needs of the compensation capacitor, enabling accurate detection of sensing currents despite large reference currents.
Implementation Method 1
a capacitive compensation circuit is utilized to generate a compensation current that can reduces the reference current
Data Source
AI summary
A touch circuit including an integrator circuit and a compensation circuit is provided. The integrator circuit includes a first terminal, a second terminal and an output terminal. The first terminal of the integrator circuit is coupled to a touch sensor, and the second terminal of the integrator circuit is coupled to a first voltage. The compensation circuit includes a first terminal and a second terminal. The first terminal of the compensation circuit is coupled to the first terminal of the integrator circuit, and the second terminal of the compensation circuit is coupled to a second voltage. When the touch circuit senses a sensing current from the touch sensor, the first voltage is increased and the second voltage is decreased.