Digital transmission circuit and method providing selectable power consumption via single-ended or differential operation
First Claim
1. A transmission circuit for transmitting a digital signal to one or more interface conductors, comprising:
- an output driver having a differential input for receiving a differential input signal pair and one or more outputs coupled to said one or more interface conductors;
a pair of pre-driver circuits each having an output coupled to an associated signal of said differential input signal pair;
a control circuit for selectively disabling power supplied to at least one of said pre-driver circuits in response to a low-power selection state of a control signal, whereby power consumption of said transmission circuit is reduced while transmitting data through said output driver, wherein said control circuit disables at least a portion of both of said pair of pre-driver circuits in response to said low-power selection state of said control signal; and
a single-ended to differential signal converter having an output coupled to an input of said output driver, and wherein said control circuit disables power supplied to said single-ended to differential signal converter when said control circuit enables said pair of pre-driver circuits in response to a high-power selection state of said control signal.
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Accused Products
Abstract
A digital transmission circuit and method providing selectable power consumption via single-ended or differential operation improves the flexibility of an interface while reducing power consumption when possible. A differential path is provided through the transmitter output driver stages and portions are selectively disabled when the transmission circuit is in a lower-power operating mode. A single-ended to differential converter circuit can be used to construct a differential signal for output to the final driver stage. The selection of power mode can be made via feedback from a channel quality measurement unit or may be hardwired or selected under programmatic control. The longer delay or skew of the lower-power single-ended mode is compensated for by the relaxed requirements of the channel when conditions permit the use of the lower-power single-ended mode.
46 Citations
21 Claims
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1. A transmission circuit for transmitting a digital signal to one or more interface conductors, comprising:
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an output driver having a differential input for receiving a differential input signal pair and one or more outputs coupled to said one or more interface conductors; a pair of pre-driver circuits each having an output coupled to an associated signal of said differential input signal pair; a control circuit for selectively disabling power supplied to at least one of said pre-driver circuits in response to a low-power selection state of a control signal, whereby power consumption of said transmission circuit is reduced while transmitting data through said output driver, wherein said control circuit disables at least a portion of both of said pair of pre-driver circuits in response to said low-power selection state of said control signal; and a single-ended to differential signal converter having an output coupled to an input of said output driver, and wherein said control circuit disables power supplied to said single-ended to differential signal converter when said control circuit enables said pair of pre-driver circuits in response to a high-power selection state of said control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A transmission circuit for transmitting a digital signal to one or more interface conductors, comprising:
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an output driver having a differential input for receiving a differential input signal pair and one or more outputs coupled to said one or more interface conductors; a pair of pre-driver circuits each having an output coupled to an associated signal of said differential input signal pair; a control circuit for selectively disabling power supplied to at least one of said pre-driver circuits in response to a low-power selection state of a control signal, whereby power consumption of said transmission circuit is reduced while transmitting data through said output driver; a first multiplexer for selecting between a pair of input signals and alternatively selecting an input signal from said pair of input signals in conformity with a data clock input, and wherein said first multiplexer has an output coupled to an input of a first one of said pre-driver circuit pair; and a second multiplexer for selecting between an inverted pair of signals corresponding to said pair of input signals and alternatively selecting an inverted input signal from said inverted pair of signals in conformity with said data clock input, and wherein said second multiplexer has an output coupled to an input of a second one of said pre-driver circuit pair, and wherein said control circuit selectively disables said second multiplexer when said control signal is in said low-power selection state. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification