High Speed Serial Interface Grounding and GPIO Configuration
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Solution Overview
Problem
High-speed differential signaling interfaces face challenges in achieving nominal differential impedance and adequate isolation due to the trade-offs between ground contacts and I/O contacts, leading to high cross-talk jitter and inefficient use of interconnect package size.
Innovation Solution
A rectilinear array configuration where pairs of transmitter and receiver contacts alternate with ground contacts, with a permanent ground contact adjacent to each pair in the fifth column and the remaining contacts used as general purpose input/output (GPIO) contacts, providing effective shielding while maximizing GPIO availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ground contacts are permanently connected to ground to provide adequate shielding for high-speed differential signaling contacts, then cross-talk jitter is reduced, but the number of available GPIO contacts decreases
Solution Approach 1:
The patent implements a dynamic grounding system where contacts in the fifth column can be switched between ground and GPIO functions based on real-time signal integrity requirements. The controller monitors differential signaling contacts and automatically grounds adjacent contacts when high-speed differential signals are detected, providing adaptive shielding that reduces cross-talk jitter while maximizing GPIO availability when not needed.
Solution Approach 2:
The system changes the electrical state parameter of contacts dynamically - switching between ground potential and high-impedance GPIO states based on operational requirements. This allows the same physical contacts to serve different functions (shielding or I/O) depending on the signal environment, resolving the contradiction between shielding effectiveness and contact versatility.
2Reliability
If as many ground contacts as possible are used to surround each pair of high-speed differential signaling contacts, then nominal differential impedance and isolation are achieved, but the number of I/O contacts decreases and package size increases
Solution Approach 1:
The patent employs dynamic switching to activate ground contacts only when high-speed differential signals are present on adjacent contacts. During normal operation, contacts remain in high-impedance state to maximize I/O availability. When differential signals are detected, the controller automatically grounds the surrounding contacts to provide necessary shielding, thus achieving signal isolation only when required and maximizing productivity otherwise.
Solution Approach 2:
The system periodically monitors the state of differential signaling contacts and switches grounding contacts on and off accordingly. This periodic activation ensures that shielding is provided only during periods when high-speed signals are present, reducing the overall time that contacts are dedicated to grounding and increasing their availability for I/O functions during other periods.
3Adaptability or versatility
If GPIO contacts are used instead of ground contacts in the fifth column, then contact versatility is improved, but cross-talk shielding becomes inadequate
Solution Approach 1:
The patent implements dynamic switching that allows contacts to transition between GPIO and ground functions based on real-time signal conditions. When high-speed differential signals are detected on adjacent contacts, the system automatically switches the fifth column contacts to ground state to provide necessary shielding. When no differential signals are present, the contacts remain in GPIO mode, thus maintaining versatility while providing protection when needed.
Solution Approach 2:
The controller acts as an intermediary that monitors signal conditions and mediates the functional state of contacts. It detects differential signaling activity and switches contacts between ground and high-impedance states accordingly, enabling the contacts to serve as either shielding or I/O based on the operational context, thus resolving the contradiction between shielding effectiveness and functionality.
Data Source
AI summary
A high speed serial interface comprises a rectilinear array of rows and columns of contact sites on a substrate. In the first four columns, pairs of transmitter and receiver contacts alternate row-by-row with pairs of ground contacts In the fifth column, there is a permanent (or hard) ground contact adjacent to each transmitter or receiver contact pair located in a row in the third and fourth columns and the remaining contacts in the fifth column are general purpose input/output (GPIO) contacts. As a result, up to 50 percent of the contacts in the fifth column may be GPIO contacts. In the sixth column, all the contacts are GPIO contacts.