USB Data Receiving Apparatus Stabilizing Output During EOP Period
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Solution Overview
Problem
USB communications during the EOP period and preceding periods are not reliable due to noise and minimal signal differences, leading to unreliable output from receiving comparators.
Innovation Solution
A data receiving apparatus with a comparator for differential input, a trigger generation section, a storage section, and a selection section that generates and uses a trigger signal to stabilize outputs before phase changes, ensuring reliable data reception during EOP and preceding periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a receiving comparator is used to receive USB differential signals, then data reception function is achieved, but output reliability deteriorates during EOP period due to noise and minimal signal differences
Solution Approach 1:
The trigger generation section generates a trigger signal in advance when detecting the transition from out-of-phase to in-phase signals, before the EOP period begins. This preliminary trigger signal activates the storage section to save the last valid output, preparing the system to maintain reliable output during the upcoming EOP period when noise would otherwise cause unreliable comparator output.
2Reliability
If noise canceling circuits are added to reduce noise influence, then signal quality improves, but device complexity increases
Solution Approach 1:
The trigger generation section acts as an intermediary that detects signal phase transitions and generates trigger signals to control the storage and selection sections. This intermediary mechanism provides a simple yet effective way to manage the EOP period without requiring complex noise canceling circuits, thus improving signal quality while minimizing circuit complexity.
3Stability of the object's composition
If a correction circuit is added to stabilize comparator output during EOP, then output stability improves, but device complexity increases
Solution Approach 1:
The storage section saves the last valid output signal before the EOP period begins, based on a trigger signal generated in advance. During the EOP period, the selection section outputs this saved signal, providing stability without requiring a complex correction circuit that would continuously adjust the comparator output. This preliminary action approach achieves output stability with minimal circuit complexity.
4Duration of action of moving object
If the receiving comparator operates during EOP period, then continuous data reception is maintained, but output reliability deteriorates due to minimal potential difference
Solution Approach 1:
The selection section acts as an intermediary between the receiving comparator and the output, switching to output the saved signal from the storage section during the EOP period when the comparator output is unreliable. This intermediary mechanism maintains continuous data reception functionality while ensuring output reliability by bypassing the unreliable comparator output during EOP.
Data Source
AI summary
A data receiving apparatus which makes it possible to obtain reliable received data during EOP period and a preceding period, and which makes it possible to receive serial data in a reliable manner. Data receiving apparatus 100 is provided with receiving comparator 102 which has first signal line 101a and second signal line 101b for differential input; NOR circuit 105 that outputs a logical output, as a trigger signal, at the time the first signal and the second signal have changed from out-of-phase to in-phase; and D-FF circuit 107 that retrieves, by means of a trigger signal from NOR circuit 105, and holds an output RCV of receiving comparator 102; wherein selection circuit 108 selects the output of receiving comparator 102, when the first signal of first signal line 101a and the second signal of second signal line 101b are out-of-phase with each other, and outputs, as received data, a value held in D-FF circuit, when the first signal and the second signal have changed from out-of-phase to in-phase.