Input/output circuit
First Claim
1. An input/output circuit comprising:
- a clock and data recovery circuit that extracts clock and data from input data, said clock and data recovery circuit capable of measuring an operational margin thereof in a temporal direction and in a voltage direction; and
an optimization control circuit that performs a control so that at least one of a characteristic of a pre-emphasis driver circuit that pre-emphasizes and drives output data and a characteristic of an equalizer circuit that equalizes the input data, are optimized, based on a measurement result of the operational margin of said clock and data recovery circuit.
3 Assignments
0 Petitions
Accused Products
Abstract
Disclosed is a SERDES circuit including a clock and data recovery circuit that allows operational margin in temporal and voltage directions to be measured, using a phase offset signal and a threshold voltage control signal, a pre-emphasis driver circuit and an equalizer circuit in order to reduce ISI on a transmission line, and an optimization control circuit for controlling the overall circuit. The optimization control circuit controls an equalizer control signal that is for adjusting characteristics of the equalizer circuit and a driver control signal that is for adjusting characteristics of the pre-emphasis driver circuit and sets the equalizer control signal and driver control signal so that the operational margin of the clock and data recovery circuit is maximized.
14 Citations
20 Claims
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1. An input/output circuit comprising:
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a clock and data recovery circuit that extracts clock and data from input data, said clock and data recovery circuit capable of measuring an operational margin thereof in a temporal direction and in a voltage direction; and an optimization control circuit that performs a control so that at least one of a characteristic of a pre-emphasis driver circuit that pre-emphasizes and drives output data and a characteristic of an equalizer circuit that equalizes the input data, are optimized, based on a measurement result of the operational margin of said clock and data recovery circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A clock and data recovery circuit for a SERDES (SERializer and DESerializer) circuit, said clock and data recovery circuit comprising:
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a first data sampling circuit that samples input data; a phase comparator that receives the input data sampled by said data sampling circuit and detects a phase relationship between a clock signal and the sampled input data; a phase controller that outputs a phase control signal based on a result of a phase comparison by said phase comparator; a first phase interpolator that generates a second clock signal having a phase interpolated based on the phase control signal, the clock signal from said phase interpolator being supplied to said data sampling circuit, thereby forming a loop, said phase controller generating a second phase control signal different from the first phase control signal, a second phase interpolator that receives said second phase control signal output from said phase controller and generates a second clock signal, phase-interpolated based on said second phase control signal; a threshold voltage generator that generates a threshold voltage; a second data sampling circuit that samples the input data responsive to said second clock signal from said second phase interpolator and the threshold voltage; and a comparison circuit that compares the data sampled by said data sampling circuit and the data sampled by said second data sampling circuit, a result of the comparison by said comparison circuit being supplied to an optimization control circuit as an error detection result, said optimization control circuit performing a control so that at least one of a characteristic of a pre-emphasis driver circuit that pre-emphasizes and drives output data and a characteristic of an equalizer circuit that equalizes the input data, are optimized, as based on the error detection result of said clock and data recovery circuit. - View Dependent Claims (15)
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16. A method of optimizing a characteristic of at least one of a pre-emphasis driver circuit that pre-emphasizes and drives output data from an input/output circuit and an equalizer circuit that equalizes input data to the input/output circuit, said method comprising:
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measuring an operational margin in a temporal direction and in a voltage direction for said input data, using a clock and data recovery circuit that extracts clock and data from the input data; and by using an optimization control circuit, performing a control so that said at least one characteristic is optimized, based on of the operational margin. - View Dependent Claims (17, 18, 19, 20)
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Specification