Touchscreen Driving Circuit With Low-Pass EMI Suppression
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Solution Overview
Problem
Conventional methods to reduce electromagnetic interference (EMI) in touch control chips, such as changing device layout and using EMI shielding films, are costly and increase design complexity, and there is a need for a more efficient solution.
Innovation Solution
A driving circuit with low-pass filter circuits integrated between control units and transistors in the pull-up and pull-down units, which reduces the switching speed of transistors and thereby suppresses high-frequency components of the switching current, effectively reducing EMI without altering the device layout or using shielding films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If EMI shielding films are used to suppress electromagnetic interference, then EMI is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the EMI suppression function from the physical domain (shielding films) and implements it in the electrical domain through low-pass filter circuits. The filter circuits are integrated directly into the driving circuit, separating the EMI mitigation function from the overall device structure and eliminating the need for additional shielding components.
Solution Approach 2:
The patent replaces the mechanical/physical EMI shielding approach (shielding films and layout changes) with an electrical solution (low-pass filter circuits). This substitution eliminates the need for physical barriers and structural modifications while achieving the same EMI suppression effect through electrical filtering.
2Object-affected harmful factors
If EMI shielding films are pasted to reduce electromagnetic interference, then EMI is suppressed, but manufacturing cost increases
Solution Approach 1:
The patent merges the EMI suppression function with the existing driving circuit by integrating low-pass filter circuits into the same chip. This consolidation eliminates the need for separate EMI shielding components and their associated manufacturing processes, thereby reducing manufacturing cost while maintaining EMI suppression effectiveness.
Solution Approach 2:
The driving circuit performs its own EMI suppression function through integrated low-pass filter circuits, eliminating the need for external EMI shielding components. The circuit serves itself by filtering out high-frequency noise generated during switching operations, making the system self-sufficient in EMI mitigation.
3Object-affected harmful factors
If device layout is changed to suppress EMI, then electromagnetic interference is reduced, but design complexity increases
Solution Approach 1:
The patent extracts the EMI suppression function from the physical layout domain and implements it in the electrical circuit domain. This allows the original device layout to be maintained while achieving EMI suppression through integrated low-pass filter circuits, thereby avoiding the design complexity associated with layout modifications.
Solution Approach 2:
The patent replaces the mechanical/layout-based EMI suppression approach with an electrical solution. Instead of modifying the physical arrangement of components, the low-pass filter circuits are integrated into the driving circuit to filter out high-frequency noise, simplifying the design process while maintaining EMI suppression effectiveness.
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 significantly reduces EMI emissions from touch control chips, saving costs and maintaining product compactness and performance.
Implementation Method 1
a first low-pass filter circuit, coupled between the control unit and the first pull-up unit; and a second low-pass filter circuit, coupled between the control unit and the first pull-down unit
Implementation Method 2
it will generate electromagnetic interference (EMI). EMI signals have both a wide range of frequencies (from a few hundred to megahertz) and a certain amplitude, which can pollute the electromagnetic through conduction and radiation
Data Source
AI summary
The present disclosure discloses a driving circuit and a related chip and electronic device. The driving circuit is configured to drive a load and includes: a control unit, configured to generate a first control signal and a second control signal; a first output terminal, coupled to the capacitive touch screen; a mutual capacitive driving circuit, including: a first pull-up unit, configured to selectively pull up the first output terminal coupled to a high voltage level according to the first control signal; a first pull-down unit, configured to selectively couple the first output terminal to a low voltage level according to the second control signal; a first low-pass filter circuit, coupled between the control unit and the first pull-up unit; and a second low-pass filter circuit, coupled between the control unit and the first pull-down unit.