Multi-phase Ground-referenced Single-ended Signaling for Noise Reduction
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Solution Overview
Problem
Conventional single-ended signaling in computing systems is susceptible to electromagnetic noise and generates significant simultaneous switching noise, while differential signaling is expensive in terms of interconnect resources and requires more pads, failing to meet the needs of high-performance, low-power, and compact computing systems.
Innovation Solution
A ground-referenced single-ended signaling system using multi-phase drivers and amplifiers that pre-charge capacitors during certain phases of a clock signal to transmit data, eliminating simultaneous switching noise by balancing transient signal and ground currents, and providing immunity to common mode noise through a common gate amplifier configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional single-ended signaling is used, then fewer signal pads and interconnect resources are required, but the system generates significant simultaneous switching noise and has poor noise tolerance
Solution Approach 1:
The patent employs multi-phase clocked operation where drivers operate in staggered phases rather than simultaneously. Each driver is enabled during specific phases of a multi-phase clock cycle, creating periodic action that distributes switching events across time. This eliminates simultaneous switching noise while maintaining single-ended signaling's resource efficiency.
2Quantity of substance
If conventional single-ended signaling is used, then fewer signal pads and interconnect resources are required, but the system has poor noise tolerance to electromagnetic noise
Solution Approach 1:
The multi-phase clocked operation creates periodic sampling windows where receivers are enabled only during specific phases. This periodic action allows the system to tolerate electromagnetic noise by integrating signals over multiple phases and rejecting noise that does not correlate with the periodic sampling pattern.
3Reliability
If differential signaling is used, then noise rejection and power efficiency are improved, but more signal pads and interconnect resources are required
Solution Approach 1:
The patent segments the signaling function across multiple phases and drivers operating in sequence rather than requiring simultaneous differential pairs. This segmentation allows single-ended signaling to achieve noise rejection properties similar to differential signaling by distributing the signaling burden across time phases while using fewer physical pads.
4Quantity of substance
If conventional single-ended drivers are used, then resource costs are reduced, but simultaneous switching noise increases with signal level
Solution Approach 1:
The patent uses multi-phase clocking to distribute switching actions across multiple time phases, preventing simultaneous switching of multiple drivers. This periodic staggering of driver operation eliminates the accumulation of supply noise that occurs when multiple drivers switch simultaneously, while maintaining resource-efficient single-ended signaling.
Data Source
AI summary
A system includes a control circuit and first, second, and third ground-referenced single-ended signaling (GRS) driver circuits that are each coupled to an output signal. The control circuit is configured to generate a first, second, and third set of control signals that are each based on a respective phase of a clock signal. Each GRS driver circuit is configured to pre-charge a capacitor to store a charge based on the respective set of control signals during at least one phase of the clock signal and drive the output signal relative to a ground network by discharging the charge during a respective phase of the clock signal.