Macrocell Layout for USB Differential Signal Consistency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The signal characteristics of USB differential signals (DP, DM) change depending on the type of integrated circuit device due to varying placement positions of circuit cells in the physical layer circuit, which complicates manufacturing and increases development costs.
Innovation Solution
A macrocell design with line-symmetrically disposed transmission drivers and receiver circuits, along with strategically placed resistor circuits, maintains signal characteristics across different locations and reduces the macrocell area, while allowing for efficient routing and placement of signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If automatic placement/routing technique is used for physical layer circuit, then placement flexibility is improved, but signal characteristics consistency deteriorates
Solution Approach 1:
The patent applies asymmetry by intentionally designing the macrocell layout to be line-symmetric with respect to differential signal pairs. The transmission drivers and receiver circuits are positioned asymmetrically relative to each pad, but symmetrically relative to the differential pair as a whole, ensuring that both signals experience identical signal characteristics regardless of macrocell placement location on the chip.
2Manufacturing precision
If transmission drivers and receiver circuits are disposed line-symmetrically, then signal characteristics consistency is improved, but macrocell area increases
Solution Approach 1:
The patent merges the transmission driver and receiver circuit placements by positioning both on the same side of the differential signal pads, rather than distributing them on opposite sides. This consolidation reduces the overall macrocell area while maintaining line-symmetric signal characteristics through careful positioning relative to the differential pair.
3Manufacturing precision
If resistor circuits are added for pull-up and dummy purposes, then signal characteristics are improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by adding resistor circuits only to specific signal lines that require pull-up or dummy functionality, rather than uniformly adding resistors to all signal lines. This selective approach improves signal characteristics where needed while minimizing the increase in overall device complexity.
Data Source
AI summary
A macrocell including a physical layer circuit includes a transmitter circuit and a receiver circuit connected with pads for differential signals DP and DM. The transmitter circuit includes a transmission driver which drives a signal line for the DP and a transmission driver which drives a signal line for the DM. When a direction from a side SD1 to a side SD3 of the macrocell is defined as a first direction, the transmission drivers are disposed on the side of the pads for the DP and DM in the first direction and are disposed line-symmetrically about a line SYL, and the receiver circuit is disposed on the side of the transmitter circuit in the first direction. A routing region of signal lines SLR1 and SLR2 for connecting the receiver circuit with the pads for the DP and DM is provided in the region between the transmission drivers.