Balanced impedance method for differential signaling
AssigneeAnalog Devices, Inc.
InventorsMark Sayuk, Ronald Kapusta
Life of this patent
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Abstract
A system and method for implementing a differential signaling driver with a common-mode voltage not equal to one half the power supply voltage using voltage-mode techniques. Embodiments of the present invention maintain balanced impedance at the signal output. In an embodiment, a driver may have multiple operating modes for each potential supply voltage or common-mode voltage. In an embodiment, each potential mode may involve configuring the driver by activating or deactivating switches or resistors in the driver and each potential mode may have different resistor values.
Claims19
A differential signaling driver comprising:
- a first pair of switches, each provided in a circuit path from a respective output terminal to a first supply voltage,
- a first pair of resistors, one provided in each circuit path from the respective output terminal to the first supply voltage
- a second pair of switches, each provided in a circuit path from the respective output terminals to a second supply voltage,
- a second pair of resistors, one provided in each circuit path from the respective output terminal to the second supply voltage, and
- a third pair of resistors, one coupled to each output terminal and to a common one of the supply voltages;
- wherein output impedances at the output terminals are balanced.
A transmission system, comprising:
- a differential signaling driver having a pair of outputs for a differential output signal, the driver circuit having balanced impedances at the outputs, the differential output signal having a common-mode voltage that deviates from one-half the supply voltage;
- a transmission line having a pair of conductors coupled to output terminals of the driver circuit;
- and
- a receiver circuit having a termination resistor coupled across the conductors.
Dependencies are inferred from the claim text.