Cross-Domain Interface Circuit for Modulated Supply Signal Conversion
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Solution Overview
Problem
Existing input devices face challenges in transmitting data signals between components operating at different power supply voltage domains due to incompatibility caused by modulated power supplies, leading to issues with signal interpretation and parasitic capacitance affecting sensor electrodes.
Innovation Solution
A cross-domain interface circuit is implemented within an integrated circuit, featuring a first conversion circuit in one power supply voltage domain and a second conversion circuit in another domain, which generates intermediate differential signals to facilitate communication across domains, reducing parasitic capacitance effects by modulating power supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a modulated power supply is used to guard sensor electrodes from display electrodes, then electromagnetic interference is reduced, but data signal compatibility between components is lost
Solution Approach 1:
A cross-domain interface circuit is introduced as an intermediary component between the modulated domain (sensor electrodes) and the unmodulated domain (display electrodes). This interface circuit includes domain conversion circuits that translate data signals from one power supply domain to another, enabling compatible communication while maintaining the modulated power supply structure for electromagnetic interference protection.
Solution Approach 2:
The patent changes the power supply parameters by creating separate modulated and unmodulated power supply domains. The modulated power supply (VDD_SENSOR, VSS_SENSOR) is used for sensor electrodes to provide electromagnetic shielding, while the unmodulated power supply (VDD_DISPLAY, VSS_DISPLAY) is used for display electrodes. Data signals are converted between these domains with different voltage reference levels, allowing each domain to operate with optimal parameters independently.
2Object-affected harmful factors
If separate modulated power supply domains are used for sensor and display electrodes, then electromagnetic protection is improved, but device complexity increases
Solution Approach 1:
The power supply system is segmented into distinct modulated and unmodulated domains. Each domain has its own power supply voltage references (VDD_SENSOR/VSS_SENSOR for modulated, VDD_DISPLAY/VSS_DISPLAY for unmodulated), allowing independent optimization. The cross-domain interface circuit is also segmented into separate domain conversion circuits that handle signal translation between domains, distributing the complexity across modular functional blocks.
3Device complexity
If data signals are transmitted directly between different power supply domains, then circuit simplicity is maintained, but signal accuracy deteriorates due to parasitic capacitance
Solution Approach 1:
The cross-domain interface circuit acts as an intermediary that properly translates data signals between power supply domains with different voltage references. This prevents direct coupling between domains that would create parasitic capacitance issues, while still enabling accurate signal transmission. The interface circuit buffers and converts signals, eliminating the harmful direct capacitive coupling path.
Data Source
AI summary
A method for converting data signals from one power supply voltage domain for use in another power supply voltage domain. The method includes receiving the data signal at a first node of the integrated circuit, wherein the first node is within the first power supply voltage domain. The method also includes generating a first intermediate differential signal from the data signal via a first conversion circuit of the integrated circuit. The method further includes communicating the first intermediate differential signal to a first cross-coupled latch, wherein the first cross-coupled latch generates a first output signal based on the first intermediate differential signal. The method also includes outputting the first output signal from a second node of the integrated circuit, wherein the second node is in the second power supply voltage domain. Other embodiments, such as an integrated circuit, and an input device, are also provided.