USB Circuit Apparatus Dynamic Signal Path Selection
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Solution Overview
Problem
Existing USB circuit apparatuses fail to effectively improve signal characteristics for full-speed (FS) and low-speed (LS) USB communications, as they rely on bus switching circuits that can degrade signal quality due to internal resistance and other factors, unlike high-speed (HS) communication which involves resynchronization and amplitude adjustment.
Innovation Solution
A circuit apparatus with a bus monitoring circuit that controls a bus switching circuit to disconnect and reconnect USB buses based on signal detection, allowing for FS and LS packet transfer through physical layer circuits and processing circuits, thereby improving signal quality by bypassing the bus switching circuit for FS and LS modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If FS USB signal propagates through the bus switching circuit, then the circuit can maintain simple signal path routing, but the internal resistance and factors of the bus switching circuit degrade signal characteristics
Solution Approach 1:
The patent implements dynamic signal path selection by detecting communication mode (HS or FS/LS) and automatically switching between two different signal routing paths. For HS mode, signals route through the processing circuit for resynchronization and amplitude adjustment. For FS/LS mode, signals route directly through the bus switching circuit without processing circuit intervention, thereby optimizing signal characteristics for each mode.
Solution Approach 2:
The patent segments the signal transmission path into two distinct routes: one through the processing circuit for HS mode with resynchronization capability, and another direct route through the bus switching circuit for FS/LS mode. This segmentation allows each path to be optimized independently for its specific communication mode, preventing FS signals from deteriorating while maintaining HS signal quality.
2Device complexity
If the bus switching circuit is used for FS communication, then the circuit structure remains simple, but no signal characteristic improvement is performed and signal quality deteriorates
Solution Approach 1:
The patent implements dynamic path selection that activates the processing circuit only when HS mode is detected. For FS mode, the system uses the simpler direct routing through the bus switching circuit but with the understanding that this path is intentionally selected for FS operations. The bus monitoring circuit dynamically determines which path to use based on communication mode detection.
Data Source
AI summary
A circuit apparatus includes physical layer circuits to which buses compliant with the USB standard are coupled, a processing circuit that performs an FS transfer process, a bus monitoring circuit that monitors the buses, and a bus switching circuit that turns on or off the coupling between a first bus and a second bus based on the result of the monitoring. One of the physical layer circuits includes an FS receiver, an FS driver, and a pull-up control circuit, and the other physical layer circuits includes an FS receiver and an FS driver. When FS_J is detected on the second bus, the bus monitoring circuit turns off the coupling achieved by the bus switching circuit, turns on the pull-up operation performed by the pull-up control circuit, and turns on the FS transfer process performed by the processing circuit.