SYSTEM HAVING CORRECTION UNIT AND CORRECTING METHOD THEREOF

• US 20110128045A1
• Filed: 11/15/2010
• Published: 06/02/2011
• Est. Priority Date: 12/02/2009
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Fujitsu Semiconductor Limited (Fujitsu Limited)
• Inventors: Nakamoto, Hiroyuki
• Granted Patent: US 8,289,197 B2
• Time in Patent Office: Days
• US Class Current: 327/50
• CPC Class Codes: H03K 5/2481 with at least one differential stage
• CPC Class Codes: H03K 5/249 using clock signals
• CPC Class Codes: H04L 25/06 Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection

Abstract

A system has a corrected unit, and a correction unit that performs binary search of a correction value with which an output of the corrected unit gets close to a reference value and feeds back the correction value to the corrected unit. The correction unit performs the additional comparison for comparing a first output of the corrected unit corresponding to a first correction value searched by the binary search and a second output, which is an output of the corrected unit corresponding to a second correction value that is adjacent to the first correction value and is an output that the voltage relationship to the reference value is opposite to the first output, and for selecting the first or second correction value corresponding to the first or second output closer to the reference value, and feeds back the selected correction value to the corrected unit.

Claims

1. A system comprising:

a corrected unit; and

a correction unit that performs binary search of a correction value with which an output of the corrected unit gets close to a reference value and feeds back the correction value to the corrected unit, wherein

the correction unit performs the additional comparison for comparing a first output of the corrected unit corresponding to a first correction value searched by the binary search and a second output, which is an output of the corrected unit corresponding to a second correction value that is adjacent to the first correction value and is an output that the voltage relationship to the reference value is opposite to the first output, and for selecting the first or second correction value corresponding to the first or second output closer to the reference value, and feeds back the selected correction value to the corrected unit.

2. The system according to claim 1, wherein

the correction unit determines either one of a pair of correction values adjacent to the first correction value as the second correction value, according to the voltage relationship between the reference value and the first output in the additional comparison.

3. The system according to claim 1, wherein

the correction unit compares a first absolute value, which is a difference between the first output and the reference value, and a second absolute value, which is a difference between the second output and the reference value, in the additional comparison, and selects the first or second correction value corresponding to the first or second output having the smaller absolute value by use of the result of the additional comparison.

4. The system according to claim 3, wherein

the corrected unit outputs a differential output signal as the output;

and

the correction unit outputs a difference of the differential signals of the first output as the first absolute value, and also outputs a difference of the differential signals of the second output as the second absolute value.

5. The system according to claim 4, wherein

the correction unit includes:

a comparator having a pair of input terminals to which the differential output signals of the corrected unit are inputted, a differential amplifier to which the differential output signals inputted to the pair of input terminals are inputted through a pair of input capacitances and which drives an output according to a difference of the differential output signals, an input-output switch disposed between an input and an output of the differential amplifier, and an input switch that couples the pair of input terminals to the pair of input capacitances by a straight coupling of a normal phase or a cross coupling of a reverse phase; and

a control unit that controls the input-output switch and the input switch of the comparator and generates the correction value according to an output of the comparator, wherein

the comparator has a first mode in which the input-output switch is turned on, and a differential signal of the first output is inputted with the normal phase or the reverse phase, and a second mode in which the input-output switch is turned off, and the differential signal of the second output is inputted with the reverse phase or the normal phase opposite to that of the first mode; and

the control unit determines a comparison result of the first and second absolute values according to the output of the comparator in the second mode.

6. The system according to claim 5, wherein

the comparator further has an input-pair switch disposed between an input pair of the differential amplifier;

and

in the first mode of the comparator, the input-pair switch is set to off.

7. The system according to claim 5, wherein

the comparator further has an input-pair switch disposed between an input pair of the differential amplifier;

and

in the first mode of the comparator, the input switch is set to either the normal phase or the reverse phase according to the polarity of a difference of the differential output signal of the first output to the first correction value searched in the binary search, and the input-pair switch is set to off.

8. The system according to claim 5, wherein

in the binary search, in a comparison mode in which the input-output switch is turned off, the input switch is set to either the normal phase or the reverse phase, and the differential output signal of the corrected unit is inputted to the differential amplifier, the control unit determines the voltage relationship of the differences of the differential output signals of the corrected unit based on an output of the differential amplifier and searches a plurality of bits of the correction values on the basis of the comparison result.

9. The system according to claim 8, wherein

the comparator further has an input-pair switch disposed between the input pair of the differential amplifier;

and

in the binary search, after an auto-zero mode in which the input-output switch and the input-pair switch are turned on, the comparator is controlled to the comparison mode, and in the comparison mode, the input-pair switch is set to off.

10. The system according to I claim 1, wherein

the corrected unit outputs a differential signal according to a differential input signal;

and

the correction unit searches a correction value with which a difference of the differential output signal becomes the smallest while a difference of the differential input signal unit is maintained at zero potential.

15. The system according to claim 2, wherein

the correction unit compares a first absolute value, which is a difference between the first output and the reference value, and a second absolute value, which is a difference between the second output and the reference value, in the additional comparison, and selects the first or second correction value corresponding to the first or second output having the smaller absolute value by use of the result of the additional comparison.

16. The system according to claim 15, wherein

the corrected unit outputs a differential output signal as the output;

and

the correction unit outputs a difference of the differential signals of the first output as the first absolute value, and also outputs a difference of the differential signals of the second output as the second absolute value.

17. The system according to claim 16, wherein

the correction unit includes:

a comparator having a pair of input terminals to which the differential output signals of the corrected unit are inputted, a differential amplifier to which the differential output signals inputted to the pair of input terminals are inputted through a pair of input capacitances and which drives an output according to a difference of the differential output signals, an input-output switch disposed between an input and an output of the differential amplifier, and an input switch that couples the pair of input terminals to the pair of input capacitances by a straight coupling of a normal phase or a cross coupling of a reverse phase; and

a control unit that controls the input-output switch and the input switch of the comparator and generates the correction value according to an output of the comparator, wherein

the comparator has a first mode in which the input-output switch is turned on, and a differential signal of the first output is inputted with the normal phase or the reverse phase, and a second mode in which the input-output switch is turned off, and the differential signal of the second output is inputted with the reverse phase or the normal phase opposite to that of the first mode; and

the control unit determines a comparison result of the first and second absolute values according to the output of the comparator in the second mode.

18. The system according to claim 17, wherein

the comparator further has an input-pair switch disposed between an input pair of the differential amplifier;

and

in the first mode of the comparator, the input-pair switch is set to off.

19. The system according to claim 18, wherein

the comparator further has an input-pair switch disposed between an input pair of the differential amplifier;

and

in the first mode of the comparator, the input switch is set to either the normal phase or the reverse phase according to the polarity of a difference of the differential output signal of the first output to the first correction value searched in the binary search, and the input-pair switch is set to off.

20. The system according to claim 19, wherein

in the binary search, in a comparison mode in which the input-output switch is turned off, the input switch is set to either the normal phase or the reverse phase, and the differential output signal of the corrected unit is inputted to the differential amplifier, the control unit determines the voltage relationship of the differences of the differential output signals of the corrected unit based on an output of the differential amplifier and searches a plurality of bits of the correction values on the basis of the comparison result.

21. The system according to claim 20, wherein

the comparator further has an input-pair switch disposed between the input pair of the differential amplifier;

and

in the binary search, after an auto-zero mode in which the input-output switch and the input-pair switch are turned on, the comparator is controlled to the comparison mode, and in the comparison mode, the input-pair switch is set to off.

11. A system comprising:

a corrected unit to which a differential signal is inputted and which outputs a differential signal; and

a correction unit that performs binary search of a correction value such that a difference of the differential output signal outputted when a difference of the differential input signal has zero potential gets close to a reference value zero and feeds back the correction value to the corrected unit, wherein

the correction unit performs additional comparison for comparing a first differential output signal of the corrected unit corresponding to a first correction value searched by the binary search and a second differential output signal, which is a differential output signal of the corrected unit corresponding to a second correction value that is adjacent to the first correction value and is an output that the voltage relationship of the differential output signal is opposite to the first differential output signal, and for selecting the first or second correction value corresponding to the first or second differential output signal with the difference being closer to the reference value zero, and feeds back the selected correction value to the corrected unit.

12. The system according to claim 11, wherein

the correction unit includes:

a comparator having a pair of input terminals to which differential output signals of the corrected unit are inputted, a differential amplifier to which the differential output signals inputted to the pair of input terminals are inputted through a pair of input capacitances and which drives an output according to a difference of the differential output signals, an input-output switch disposed between an input and an output of the differential amplifier, an input switch that couples the pair of input terminals to the pair of input capacitances by a straight coupling of a normal phase or a cross coupling of a reverse phase, and an input-pair switch disposed between the pair of input terminals; and

a control unit that controls the input-output switch, the input switch, and the input-pair switch of the comparator and generates the correction value according to an output of the comparator, wherein

the comparator has a first mode in which the input-output switch is turned on, the input-pair switch is turned off, and a differential signal of the first output is inputted with the normal phase or the reverse phase, and a second mode in which the input-output switch and the input-pair switch are turned off, and the differential signal of the second output is inputted with the reverse phase or the normal phase opposite to that of the first mode; and

the control unit determines a comparison result of the first and second absolute values according to the output of the comparator in the second mode.

13. The system according to claim 12, wherein

the control unit has, in the binary search, an auto-zero mode in which the input-output switch and the input-pair switch are turned off and a comparison mode in which the input-output switch and the input-pair switch are turned off, and the differential output signal of the corrected unit is inputted with the reverse phase or the normal phase opposite to that of the first mode to the differential amplifier,

the control unit, in the comparison mode, determines the voltage relationship of the differences of the differential output signals of the corrected unit based on an output of the differential amplifier and searches a plurality of bits of the correction values on the basis of the comparison result.

14. A correcting method for a corrected unit in which an output of the corrected unit is monitored and a correction value to be fed back to the corrected unit is searched, comprising:

a binary search in which a correction value with which an output of the corrected unit gets closer to a reference value is binary-searched;

an additional comparison in which a first output of the corrected unit corresponding to a first correction unit searched by the binary search is compared with a second output, which is an output of the corrected unit corresponding to a second correction value that is adjacent to the first correction value and is an output that the voltage relationship to the reference value is opposite to that of the first output, and the first or second correction value corresponding to the first or second output closer to the reference value is selected; and

a feedback in which the selected correction value is fed back to the corrected unit.