PCIe Sideband Voltage Negotiation Without Level Shifters
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Solution Overview
Problem
Current PCIe standards lack a standardized method for negotiating lower sideband voltages between adapters and platforms, often requiring space-consuming level shifters to default to higher voltages, which is inefficient and wasteful.
Innovation Solution
The implementation of a voltage control pin and voltage indication signal (VIO_CFG) that allows PCIe adapters and platforms to negotiate and select compatible sideband voltage levels, such as 0.8V, 1.2V, 1.8V, and 3.3V, without the need for level shifters, enabling backward compatibility and power savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If level shifters are used to default to higher voltages, then voltage compatibility is ensured, but device area increases
Solution Approach 1:
The patent extracts the voltage level indication function from the data signal itself by using a dedicated voltage indication signal (VIO_CFG) that separately communicates the desired voltage level. This allows the system to eliminate level shifters while maintaining voltage compatibility, as the voltage level is negotiated through this separate indication mechanism rather than forcing all devices to default to higher voltages.
Solution Approach 2:
The voltage indication signal acts as an intermediary between the PCIe adapter and platform, carrying voltage level information without requiring direct voltage level matching. This intermediary mechanism enables voltage negotiation and compatibility without the need for physical level shifter circuits, thereby reducing device area while maintaining adaptability.
2Adaptability or versatility
If level shifters are used to ensure voltage compatibility, then voltage negotiation is possible, but device complexity increases
Solution Approach 1:
The patent separates the voltage negotiation function from the data communication function by extracting voltage level indication into a dedicated signal path. This eliminates the need for complex level shifter circuits while preserving voltage negotiation capability, as the voltage level is communicated through the simplified VIO_CFG indication mechanism.
Solution Approach 2:
The patent replaces the mechanical/electrical level shifter circuitry with a signal-based voltage indication mechanism. Instead of using physical voltage level conversion circuits, the system uses electrical signals (VIO_CFG) to communicate voltage level preferences, thereby reducing device complexity while maintaining negotiation capability.
3Adaptability or versatility
If higher voltage is used by default, then compatibility with existing standards is maintained, but power consumption increases
Solution Approach 1:
The patent introduces dynamic voltage negotiation through the VIO_CFG indication signal, allowing the system to adaptively select voltage levels based on actual requirements rather than statically defaulting to higher voltages. This dynamic mechanism enables backward compatibility while reducing power consumption by operating at lower voltages when appropriate.
Solution Approach 2:
The patent changes the voltage parameter from a fixed default value to a negotiable parameter communicated through the voltage indication signal. This allows the system to select optimal voltage levels (including lower consumption levels) while maintaining compatibility with existing standards through the negotiation mechanism, thereby reducing overall power consumption.
Data Source
AI summary
Aspects relate to techniques for controlling signal voltage levels across a wired data link for data communication between apparatuses. A first device can advertise multiple supported signal voltage levels to a peer device connected by the wired data link. The devices can implement the same signal voltage level(s) or different signal voltage levels. The peer devices can compare and select a compatible signal voltage level for data communication. The first device can provide a signal voltage indication signal that is configurable to a plurality of voltage levels corresponding to a plurality of signal voltages. At least one of the plurality of voltage levels can indicate that the first device can operate the data link at a plurality of signal voltages. In some examples, the wired data link can be a peripheral component interconnect express (PCIe) link.