Circuitry and methods minimizing output switching noise through split-level signaling and bus division enabled by a third power supply

摘要

Disclosed herein are circuitry and methods for transmitting data across a parallel bus using both high common mode and low common mode signaling. The transmitter stages are configured to work with two of three possible power supply voltages: a high Vddq voltage, a low Vssq voltage, and an intermediate Vx voltage. In one embodiment, the odd numbered transmitter stages, that drive the odd numbered outputs to the bus, use the Vddq and Vx supplies, such that the odd numbered outputs comprise high common mode signals. The even numbered transmitter stages, that drive the even numbered outputs to the bus, use the Vx and Vssq supplies, such that the even numbered outputs comprise low common mode signals.

主权项

1. A method, comprising:
generating a first power supply voltage from a first power supply, a second power supply voltage from a second power supply, and a third power supply voltage from a third power supply; supplying power to at least one circuit block from the first power supply voltage and the second power supply voltage, the second power supply voltage being lower than the first power supply voltage; generating an output from each of a plurality of transmitters; arranging the plurality of transmitters into an unbalanced configuration with a larger number of transmitters in a first group of transmitters than in a second group of transmitters; powering at least one of the plurality of transmitters having a first transmitter with the first power supply voltage and the third power supply voltage, the third power supply voltage being intermediate between the first power supply voltage and the second power supply voltage; and powering at least one of the plurality of transmitters having a second transmitter with the third power supply voltage and the second power supply voltage, the powering of the plurality of transmitters being arranged such that no one of the three power supplies source or sink current to or from more than half of the plurality of transmitters at any point in time.