PWM Serial Transceiver Waveform Shaping for Fast Low-Noise Links
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Solution Overview
Problem
Existing communication systems face a challenge in achieving a balance between increasing data transmission rate and minimizing noise on the communication path, as steeper edge slopes required for higher speeds lead to increased noise and potential signal overlap.
Innovation Solution
A transceiver design that generates shaped transmission signals with steeper leading edges and more gradual trailing edges, using a waveform shaping circuit to ensure data transmission without signal overlap, allowing for increased data transmission rates without corresponding noise increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the edge slope is made steeper to increase data transmission rate, then the communication speed increases, but the noise on the communication path increases
Solution Approach 1:
The patent segments the edge slope characteristics into two distinct parts: a steep leading edge for rapid signal transition and a gradual trailing edge for noise suppression. This segmentation allows each part of the signal waveform to serve different functions - the leading edge determines transmission speed while the trailing edge controls noise levels, thereby resolving the contradiction between speed and noise.
Solution Approach 2:
The patent applies different quality characteristics to different portions of the signal waveform. Specifically, the leading edge is designed with high slope (steep transition) to enable fast communication, while the trailing edge is designed with low slope (gradual transition) to minimize noise. This local differentiation of signal properties allows simultaneous optimization of both transmission rate and noise control.
2Speed
If the interval between successive edges is shortened to increase data transmission rate, then the communication speed increases, but signal overlap occurs causing unstable operation
Solution Approach 1:
The patent segments the bit interval into two functional zones: a leading edge region with steep slope for rapid state change and a trailing edge region with gradual slope for controlled decay. This segmentation ensures that even when bits are transmitted in quick succession, the gradual trailing edges prevent overlap between consecutive signal transitions, maintaining stable operation at high transmission rates.
Solution Approach 2:
The patent implements preliminary action by ensuring that each signal transition completes its full decay through the gradual trailing edge before the next transition begins. This preliminary completion of signal decay prevents any potential overlap with subsequent bits, thereby maintaining reliability even at increased transmission rates where bit intervals are shortened.
Data Source
AI summary
Serial data are transmitted between transceivers via a communication path, each bit expressed by a dominant code or a recessive code which vary between dominant and recessive levels, the dominant code having a greater proportion of duration at the dominant level. A device (clock master) can continuously output successive recessive codes to the communication path, in which condition a transceiver can transmit a dominant code by producing an output drive signal which overwrites a part of a recessive code, currently being received from the communication path, to the dominant level. The output drive signal is shaped with a steeper edge slope at a transition from an inactive to an active level than from the active to the inactive level, enabling an increased data transmission rate without increased noise.