Dual-Core Crosspoint Switching for Common-Mode Signal Headroom
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Solution Overview
Problem
Existing crosspoint systems face constraints in voltage headroom when handling both differential signals and common mode voltages, limiting their ability to transmit common mode information effectively, and introducing noise associated with average common mode signals.
Innovation Solution
A dual core crosspoint system is introduced, featuring a differential signal core that switches signals with common modes removed and a separate common mode core that independently switches and recombines the removed common modes with their corresponding differential signals, allowing for simultaneous transmission of common mode information without compromising voltage headroom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single crosspoint system handles both differential signals and common mode voltages simultaneously, then the system can transmit common mode information, but voltage headroom becomes constrained
Solution Approach 1:
The crosspoint system is divided into two separate cores: a differential signal core that processes only differential signals with common mode removed, and a common mode core that processes only common mode voltages. This segmentation allows each core to operate independently within its voltage range, eliminating the headroom constraints that would exist in a unified system while preserving the ability to transmit both differential and common mode information simultaneously.
Solution Approach 2:
A common mode removal circuit acts as an intermediary between the differential signal core and the common mode core. This circuit extracts the common mode voltage from the differential input signals and directs it to the common mode core, while allowing the differential signal core to process only the differential portion. This intermediary enables the separation of functions without losing either signal type.
2Loss of information
If common mode voltage is included in differential signal processing, then common mode information can be transmitted, but input noise associated with average common mode signal increases
Solution Approach 1:
By segmenting the system into separate differential and common mode processing paths, the noise associated with average common mode signals is confined to the common mode core where it can be managed independently, rather than being introduced into the differential signal path where it would degrade signal quality.
Solution Approach 2:
The common mode voltage is extracted from the differential input signals before processing and routed to a separate common mode core. This extraction removes the source of noise from the differential signal path, allowing clean differential signal processing while still preserving and transmitting the common mode information through the dedicated common mode core.
Data Source
AI summary
A dual core crosspoint system includes a differential signal core for receiving N differential input channels with common mode voltage removed and providing m differential output channels with m output stages associated with the m output channels; and a common mode core for receiving N common mode voltage input channels derived from the N differential input channels and providing m common mode voltage output channels simultaneously with the m differential output channels.