Ground referenced single-ended signaling
AssigneeNVIDIA Corporation
InventorsJohn W. Poulton, Thomas Hastings Greer, III, William J. Dally
Life of this patent
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Abstract
One embodiment of the present invention sets forth a mechanism for transmitting and receiving ground-referenced single-ended signals. A transmitter combines a direct current (DC) to DC converter including a flying capacitor with a 2:1 clocked multiplexer to drive a single-ended signaling line. The transmitter drives a pair of voltages that are symmetric about the ground power supply level. Signaling currents are returned to the ground plane to minimize the generation of noise that is a source of crosstalk between different signaling lines. Noise introduced through the power supply is correlated with the switching rate of the data and may be reduced using an equalizer circuit.
Claims20
A transmitter circuit, comprising:
- a precharge with flying capacitor sub-circuit that includes a first flying capacitor configured to be precharged to a ground supply voltage during a positive phase of a clock and a second flying capacitor configured to be precharged to the ground supply voltage during a negative phase of the clock;
- and
- a discharge and multiplexor sub-circuit that is configured to:
- couple the first flying capacitor to a single-ended signaling line during the negative phase of the clock to drive the single-ended signaling line based on a first data signal;
- and
- couple the second flying capacitor to the single-ended signaling line during the positive phase of the clock to drive the single-ended signaling line based on a second data signal.
A method comprising:
- precharging a first flying capacitor to a ground supply voltage during a positive phase of a clock;
- precharging a second flying capacitor to the ground supply voltage during a negative phase of the clock;
- coupling the first flying capacitor to a single-ended signaling line during the negative phase of the clock to drive the single-ended signaling line based on a first data signal;
- and
- coupling the second flying capacitor to the single-ended signaling line during the positive phase of the clock to drive the single-ended signaling line based on a second data signal.
Dependencies are inferred from the claim text.