Receiving device and operating method thereof
A receiving device includes a delay buffer configured to receive an analog signal and output a delayed analog signal, a phase interpolator configured to output a clock signal based on a phase compensation code signal and a reference clock signal, an analog-to-digital converter group configured to output a slope type determination signal indicating a slope of the analog signal based on the analog signal and the delayed analog signal, and a clock data restorer. The clock data restorer is configured to determine a curve type associated with a plurality of digital samples from the analog-to-digital converter group. The clock data restorer also evaluates a timing of the clock signal based on the curve type and the slope type determination signal, and outputs the phase compensation code signal to move the sample timing closer to an optimum timing.
1 . A receiving device comprising:
a delay buffer configured to receive an analog signal and output a delayed analog signal that is delayed with respect to the analog signal;
a phase interpolator configured to output, based on a phase compensation code signal and a reference clock signal, a clock signal;
an analog-to-digital converter group configured to:
output, based on the analog signal and the clock signal, a plurality of digital samples comprising a first digital sample with a first value, a second digital sample with a second value and a third digital sample with a third value, and
output, based on the analog signal and the delayed analog signal, a slope type determination signal indicating a rising slope or a falling slope of the analog signal; and
a clock data restorer configured to:
determine, based on the plurality of digital samples, a curve type indicating a convex curve or a concave curve of a curve comprising the plurality of digital samples,
obtain, based on the curve type and the slope type determination signal, an evaluation result with respect to a timing of the clock signal, and
output, based on the evaluation result, the phase compensation code signal,
wherein, in an eye diagram of the analog signal, the curve type indicates the convex curve based on an open shape of the analog signal being convex and indicates the concave curve based on the open shape of the analog signal being concave, and
wherein the clock signal is configured to sample the open shape of the eye diagram.
2 . The receiving device of claim 1 , wherein the analog-to-digital converter group comprises a plurality of analog-to-digital converters,
wherein each of the plurality of analog-to-digital converters comprises:
a successive approximation register analog-to-digital converter configured to output a digital sample by sampling the analog signal in response to an edge of the clock signal; and
a slope detector configured to output a result of comparing the analog signal with the delayed analog signal as the slope type determination signal in response to the edge of the clock signal.
3 . The receiving device of claim 2 , wherein the slope detector comprises a comparator configured to:
receive the analog signal and the delayed analog signal through input terminals,
compare the analog signal with the delayed analog signal at the edge of the clock signal, and
output a signal having a first logic level or a second logic level as the slope type determination signal.
4 . The receiving device of claim 1 , wherein the analog-to-digital converter group comprises:
a first analog-to-digital converter, a second analog-to-digital converter, and a third analog-to-digital converter that are sequentially arranged, the first analog-to-digital converter being configured to output the first digital sample, the second analog-to-digital converter being configured to output the second digital sample, and the third analog-to-digital converter being configured to output the third digital sample,
wherein the clock data restorer is further configured to:
determine the curve type as the convex curve based on the second value of the second digital sample being greater than the first value of the first digital sample and the third value of the third digital sample, and
determine the curve type as the concave curve based on the second value of the second digital sample being less than the first value of the first digital sample and the third value of the third digital sample.
5 . The receiving device of claim 1 , wherein the clock data restorer is further configured to:
determine that the timing of the clock signal is earlier than an optimum timing based on the curve type being the convex curve and a slope type being the rising slope, and
determine that the timing of the clock signal is later than the optimum timing based on the curve type being the convex curve and the slope type being the falling slope.
6 . The receiving device of claim 1 , wherein the clock data restorer is further configured to:
determine that the timing of the clock signal is later than an optimal timing based on the curve type being the concave curve and a slope type being the rising slope, and
determine that the timing of the clock signal is earlier than the optimal timing based on the curve type being the concave curve and the slope type being the falling slope.
7 . The receiving device of claim 1 , wherein the analog-to-digital converter group comprises a first analog-to-digital converter, a second analog-to-digital converter, and a third analog-to-digital converter that are sequentially arranged, the first analog-to-digital converter being configured to output the first digital sample, the second analog-to-digital converter being configured to output the second digital sample, and the third analog-to-digital converter being configured to output the third digital sample,
wherein the clock data restorer is configured to determine the curve type based on: i) a first absolute value of the first digital sample and a second absolute value of the third digital sample being greater than or equal to a reference value, and ii) a first difference value between the first value of the first digital sample and the second value of the second digital sample or a second difference value between the third value of the third digital sample and the second value of the second digital sample being greater than or equal to a reference difference value.
8 . The receiving device of claim 1 , wherein the delay buffer comprises:
a first buffer configured to:
receive the analog signal, and
output a first delayed analog signal delayed with respect to the analog signal; and
a second buffer configured to:
receive the first delayed analog signal, and
output a second delayed analog signal delayed with respect to the first delayed analog signal,
wherein the analog-to-digital converter group comprises a plurality of analog-to-digital converters,
wherein each of the plurality of analog-to-digital converters comprises:
a successive approximation register analog-to-digital converter configured to output a digital sample by sampling the analog signal in response to a first edge of the clock signal;
a clock delay buffer configured to output a delayed clock signal that is delayed with respect to the clock signal;
a first slope detector configured to output a first result of comparing the first delayed analog signal with the second delayed analog signal as a first slope type determination signal; and
a second slope detector configured to output a second result of comparing the first delayed analog signal with the second delayed analog signal as a second slope type determination signal,
wherein the first slope type determination signal and the second slope type determination signal have opposite phases to each other.
9 . The receiving device of claim 8 ,
wherein the first slope detector comprises a first comparator comprising:
a first polarity input terminal configured to receive the first delayed analog signal,
a second polarity input terminal configured to receive the second delayed analog signal,
a first input terminal configured to receive the delayed clock signal, and
a first output terminal configured to output the first slope type determination signal, and
wherein the second slope detector comprises a second comparator comprising:
a third polarity input terminal configured to receive the second delayed analog signal,
a fourth polarity input terminal configured to receive the first delayed analog signal,
a second input terminal configured to receive the delayed clock signal, and
a second output terminal configured to output the second slope type determination signal.
10 . An operating method of a receiving device, the operating method comprising:
delaying an analog signal received from the outside to output a delayed analog signal that is delayed with respect to the analog signal;
outputting, based on a phase compensation code signal and a reference clock signal, a clock signal;
outputting, based on the analog signal and the clock signal, a plurality of digital samples comprising a first digital sample with a first value, a second digital sample with a second value and a third digital sample with a third value;
outputting, based on the clock signal, the analog signal and the delayed analog signal, a slope type determination signal indicating a rising slope or a falling slope of the analog signal;
determining, based on the plurality of digital samples, a curve type indicating a convex curve or a concave curve of a curve comprising the plurality of digital samples;
obtaining, based on the curve type and the slope type determination signal, an evaluation result with respect to a timing of the clock signal; and
outputting, based on the evaluation result, the phase compensation code signal,
wherein, in an eye diagram of the analog signal, the curve type indicates the convex curve based on an open shape of the analog signal being convex and indicates the concave curve based on the open shape of the analog signal being concave, and
wherein the clock signal is configured to sample the open shape of the eye diagram.
11 . The operating method of claim 10 , wherein the outputting of the slope type determination signal comprises:
receiving the clock signal, the analog signal and the delayed analog signal;
comparing the analog signal with the delayed analog signal at an edge of the clock signal; and
outputting the slope type determination signal, wherein the slope type determination signal comprises a first logic level or a second logic level, wherein the first logic level indicates that a slope type of the analog signal is the rising slope and the second logic level indicates that the slope type of the analog signal is the falling slope.
12 . The operating method of claim 10 , wherein the outputting of the plurality of digital samples comprises outputting the first digital sample, the second digital sample, and the third digital sample by a first analog-to-digital converter, a second analog-to-digital converter, and a third analog-to-digital converter, respectively, the first analog-to-digital converter, the second analog-to-digital converter, and the third analog-to-digital converter being successively arranged,
wherein, among the first digital sample, the second digital sample and the third digital sample, the second value of the second digital sample is greater than the first value of the first digital sample and greater than the third value of the third digital sample,
wherein the determining of the curve type comprises determining the curve type as the convex curve based on the first digital sample, the second digital sample and the third digital sample.
13 . The operating method of claim 10 , wherein the outputting of the plurality of digital samples comprises outputting the first digital sample, the second digital sample and the third digital sample by a first analog-to-digital converter, a second analog-to-digital converter, and a third analog-to-digital converter, respectively, the first analog-to-digital converter, the second analog-to-digital converter, and the third analog-to-digital converter being successively arranged,
wherein, among the first digital sample, the second digital sample and the third digital sample, the second value of the second digital sample is less than the first value of the first digital sample and less than the third value of the third digital sample,
wherein the determining of the curve type comprises determining the curve type as the concave curve based on the first digital sample, the second digital sample and the third digital sample.
14 . The operating method of claim 10 , wherein the obtaining the evaluation result comprises determining that the timing of the clock signal is earlier than optimal timing based on i) the curve type being the convex curve and a slope type is the rising slope, or ii) the curve type being the concave curve and the slope type being the falling slope.
15 . The operating method of claim 10 , wherein the obtaining the evaluation result comprises determining that the timing of the clock signal is later than optimal timing when: i) the curve type is the convex curve and a slope type is the falling slope, or ii) the curve type is the concave curve and the slope type is the rising slope.