Robust method and apparatus for providing a digital single-ended output from a differential input
First Claim
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1. A method comprising:
- automatically adjusting a common mode output level of a first differential amplifier that is coupled to a first digital circuit, in response to variation in a trip point level of a second digital circuit, the second digital circuit includes a replicate of the first digital circuit to generate a trip point level that is equivalent to a trip point level of the first digital circuit.
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Abstract
An embodiment of the invention is directed to a method of automatically adjusting a common mode output level of a first differential amplifier that is connected to a first digital circuit, in response to variation in a trip point level of a second digital circuit. The second digital circuit includes a replicate of the first digital circuit to generate a trip point level that is equivalent to a trip point level of the first digital circuit. The invention may yield a single-ended digital signal whose duty cycle accurately tracks that of an input differential signal pair in a manner that is substantially independent of fabrication process skew.
90 Citations
18 Claims
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1. A method comprising:
automatically adjusting a common mode output level of a first differential amplifier that is coupled to a first digital circuit, in response to variation in a trip point level of a second digital circuit, the second digital circuit includes a replicate of the first digital circuit to generate a trip point level that is equivalent to a trip point level of the first digital circuit. - View Dependent Claims (2, 3, 4, 5)
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6. A circuit comprising:
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first differential amplifier having an output and a common mode output level adjustment input; first digital circuit having an input coupled to the output of the first differential amplifier and an output that provides a single ended digital signal in response to an output signal of the differential amplifier; second digital circuit that includes a replicate of a portion of the first circuit to generate a trip point signal that is equivalent to a trip point of the first digital circuit; and comparison amplifier having an input coupled to the second digital circuit and an output coupled to the common mode level adjustment input of the first differential amplifier to adjust the common mode output level of the first differential amplifier in response to the trip point signal of the second digital circuit. - View Dependent Claims (7, 8, 9, 10, 11)
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12. An apparatus comprising:
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at least one differential-to-single-ended circuit each including a first differential amplifier having a pair of differential inputs, a pair of differential outputs, and a common mode output level adjustment input, and a first digital circuit having an input coupled to at least one of the differential outputs and an output that provides a single-ended digital signal; digital circuitry clocked by the single ended digital signal; second digital circuit that includes a replicate of a portion of the first circuit, to generate a trip point signal that is equivalent to a trip point level of the first digital circuit; and comparison amplifier having an output coupled to the common mode level adjustment input of the first differential amplifier to adjust the common mode output level of the first differential amplifier in response to the trip point signal of the second digital circuit. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification