LVDS output driver having low supply voltage capability
First Claim
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1. An apparatus, comprising:
- a plurality of source followers, each of the plurality of source followers comprising a pull-down transistor having a source, a drain, a gate, and a bulk terminal;
a plurality of pull-up transistors, each of the plurality of pull-up transistors having a source, a drain, and a gate, wherein the drain of each of the plurality of pull-up transistors is coupled to the source of a pull-down transistor of the plurality of source followers, to output a plurality of differential signals via the drains of the plurality of pull-up transistors;
a first current source coupled to the sources of the plurality of pull-up transistors, wherein the first current source is powered by a first voltage of at least about 1.624V to 2.725V;
an operational amplifier, coupled to the first current source, to drive the first current source; and
a feedback path coupled between the drains of the plurality of pull-up transistors and an input of the operational amplifier.
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Abstract
A LVDS output driver has been disclosed. One embodiment of the LVDS output driver includes a number of source followers, each of the source followers including a pull-down transistor having a source, a drain, a gate, and a bulk terminal. The embodiment of the LVDS output driver further includes a number of pull-up transistors, each of the pull-up transistors having a source, a drain, and a gate, wherein the drain of each of the pull-up transistors is coupled to the source of a pull-down transistor of the source followers, to output a number of differential signals via the drains of the pull-up transistors. Other embodiments are described and claimed.
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Citations
13 Claims
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1. An apparatus, comprising:
- a plurality of source followers, each of the plurality of source followers comprising a pull-down transistor having a source, a drain, a gate, and a bulk terminal;
a plurality of pull-up transistors, each of the plurality of pull-up transistors having a source, a drain, and a gate, wherein the drain of each of the plurality of pull-up transistors is coupled to the source of a pull-down transistor of the plurality of source followers, to output a plurality of differential signals via the drains of the plurality of pull-up transistors; a first current source coupled to the sources of the plurality of pull-up transistors, wherein the first current source is powered by a first voltage of at least about 1.624V to 2.725V; an operational amplifier, coupled to the first current source, to drive the first current source; and a feedback path coupled between the drains of the plurality of pull-up transistors and an input of the operational amplifier.
- a plurality of source followers, each of the plurality of source followers comprising a pull-down transistor having a source, a drain, a gate, and a bulk terminal;
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2. An apparatus, comprising:
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a plurality of source followers, each of the plurality of source followers comprising a pull-down transistor having a source, a drain, a gate, and a bulk terminal; a plurality of pull-up transistors, each of the plurality of pull-up transistors m having a source, a drain, and a gate, wherein the drain of each of the plurality of the pull-up transistors is coupled to the source of a pull-down transistor of the plurality of source followers, to output a plurality of differential signals via the drains of the plurality of pull-up transistors;
a first current source coupled to the sources of the plurality of pull-up transistors;
an operational amplifier, coupled to the first current source, to drive the first current source; anda feedback path coupled between the drains of the plurality of pull-up; transistors and an input of the operational amplifier, wherein the feedback path further comprises a sensing circuit, the sensing circuit includes a plurality of transistors biased by a predetermined voltage. - View Dependent Claims (3)
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4. An apparatus, comprising:
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a plurality of source followers, each of the plurality of source followers comprising a pull-down transistor having a source, a drain, a gate, and a bulk terminal; a plurality of pull-up transistors, each of the plurality of pull-up transistors CD having a source, a drain, and a gate, wherein the drain of each of the plurality of pull-up transistors is coupled to the source of a pull-down transistor of the plurality of source followers, to output a plurality of differential signals via the drains of the plurality of pull-up transistors; a low swing differential pre-driver, coupled to the gates of the pull-down m transistors of the plurality of source followers, to drive the pull-down transistors; and a plurality of inverters, each of the plurality of inverters being coupled to the gate of each of the plurality of pull-up transistors to amplify an input signal and to apply the amplified signal to the gate of the corresponding pull-up transistor, wherein the plurality of inverters are powered by a second voltage approximately between 1.1V and 1.3V. - View Dependent Claims (5, 6, 7, 8)
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9. A method comprising:
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providing a plurality of input signals to a plurality of pull-up transistors; coupling each of the plurality of pull-up transistors to one of a plurality of pull-down transistors; driving the plurality of pull-down transistors with a plurality of differential low swing signals to output a plurality of low voltage differential signals in response to the plurality of input signals; and generating the plurality of differential low swing signals using a low swing differential pre-driver, wherein generating the plurality of differential low swing signals using the low swing differential pre-driver comprises; supplying current to a load from a second current source; sinking the current from the load via a transistor and a resistor, the transistor being coupled to the resistor in parallel; and outputting a plurality of low swing differential signals via the load to the gates of the plurality of pull-down transistors. - View Dependent Claims (10, 11)
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12. A method, comprising
providing a plurality of input signals to a plurality of pull-up transistors, coupling each of the plurality of pull-up transistors to one of a plurality of pull-down transistors; -
driving the plurality of pull-down transistors with a plurality of differential low swing signals to output a plurality of low voltage differential signals in response to the plurality of input signals; amplifying the plurality of input voltages using a plurality of inverters, each of the plurality of inverters being coupled to a distinct one of the plurality of pull-up transistors; and powering the plurality of inverters by a voltage approximately between 1.1V and 1.3V.
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13. An apparatus comprising:
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means for providing a plurality of input signals to a plurality of pull-up transistors; means for coupling each of the plurality of pull-up transistors to one of a plurality of pull-down transistors; means for driving the plurality of pull-down transistors with a plurality of differential low swing signals to output a plurality of low voltage differential signals in response to the plurality of input signals; means for generating the plurality of differential low swing signals using a low swing differential pre-driver, wherein the means for generating the plurality of differential low swing signals using the low swing differential pre-driver comprises; means for supplying current to a load from a second current source; means for sinking the current from the load via a transistor and a resistor, the transistor being coupled to the resistor in parallel; and
Inmeans for outputting a plurality of low swing differential signals via H the load to the gates of the plurality of pull-down transistors.
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Specification