Circuit Device Power Supply Segmentation for Ground Shift Isolation
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Solution Overview
Problem
Existing circuit devices that address voltage drop in USB cables primarily focus on VBUS voltage drop, neglecting issues related to voltage drops in ground lines and resulting communications errors.
Innovation Solution
A circuit device with a physical layer circuit coupled to a data bus, featuring a processing circuit that operates with ground line voltage, a level shifter, measurement circuit, and voltage generation circuit to manage power supply voltages independently of the ground line, preventing GND shifts and associated communications errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage drop compensation is performed using ground line voltage, then VBUS voltage drop can be compensated, but ground line voltage drops cause communication errors
Solution Approach 1:
The patent segments the power supply system into two independent parts: (1) ground line voltage for the processing circuit, and (2) a separate power supply line providing first and second power supply voltages for the physical layer circuit. This segmentation isolates the physical layer circuit from ground line voltage drops, preventing communication errors while maintaining the ability to compensate for VBUS voltage drops.
Solution Approach 2:
The patent introduces a separate power supply line as an intermediary between the VBUS line and the physical layer circuit. This intermediary line provides stable reference voltages (first and second power supply voltages) that are not affected by ground line potential shifts, thereby mediating the harmful effect of ground line voltage drops on communication.
2Reliability
If a separate power supply line is used for the physical layer circuit, then ground line voltage drops are prevented from affecting communication, but device complexity increases
Solution Approach 1:
The separate power supply line serves multiple functions: it provides the first power supply voltage for the physical layer circuit, provides the second power supply voltage for level shifting operations, and serves as a reference for voltage drop compensation. By making this single power supply line multi-functional, the patent reduces the need for additional separate circuits, thereby limiting the increase in device complexity.
3Adaptability or versatility
If voltage levels are shifted between processing circuit and physical layer circuit, then signal compatibility is achieved, but additional level shifter components are required
Solution Approach 1:
The patent combines the level shifting function with the power supply voltage generation. The first and second power supply voltages from the separate power supply line are used directly to enable level shifting between the processing circuit and physical layer circuit. By merging the power supply function with the level shifting requirement, the patent achieves signal compatibility without adding separate level shifter components.
Data Source
AI summary
A circuit device includes a physical layer circuit coupled to a data bus, and a processing circuit that controls the physical layer circuit and performs communications processing through the data bus. The processing circuit operates with a voltage supplied from a ground line as a power supply voltage VSS on a low potential side, and the physical layer circuit operates based on a power supply voltage VSSA on the low potential side supplied from a power supply line not coupled to the ground line in the circuit device, and a power supply voltage HVDDA on a high potential side set with reference to the power supply voltage VSSA.