Improving single-ended channel performance with a dynamic reference voltage scheme

For high-speed signaling, differential channels are now commonly used because of the improved noise immunity and receiver sensitivity that can be achieved compared to the single-ended channels that had been widely used in electronic systems until recently. However, single-ended channels have the distinct advantage of only needing one signal trace per signal, which in a well-controlled impedance, low-noise environment can provide equivalent bandwidth per pin at a lower silicon area and lower power demand than differential signals. To provide an effective low-noise environment for the receiver threshold tolerance, a power noise compensation scheme consisting of a dynamic forwarded reference voltage, is proposed. This improves the overall performance of the Elastic Interface (El) bus (Berger et al., 2007), a single-ended high speed signaling technology used in IBM systems. We explore the range of voltage differences that could be observed at the transmit and receive circuits and how those differences can be mitigated to enhance the performance of the system. Simulations for channels with varying voltage characteristics confirm the anticipated performance improvement.