Analog/digital converter and semiconductor integrated circuit device

An A/D converter comprising:

• M unitary A/D conversion units different in phase and equal in sampling rate, where M is an integer equal to or larger than 2, the A/D conversion units being connected in parallel;
• a reference A/D conversion unit connected in parallel to the M unitary A/D conversion units and having an operation clock frequency set to 1/N of an overall sampling rate of the A/D converter;
• and
• M calibration units each performing calibration at an output of a corresponding unitary A/D conversion unit, and each having a sampling-timing calibration unit adapted to correct a sampling timing or an input-signal bandwidth of the corresponding unitary A/D conversion unit so as to be equal to a sampling timing or an input-signal bandwidth of the reference A/D conversion unit, respectively,
• wherein each of the sampling-timing calibration units comprises:
• a subtracting unit adapted to calculate a conversion error signal which is a difference between an output of the calibration unit and an output of the reference A/D conversion unit;
• a sign-of-time-differentiation deriving portion that derives a sign of a time differentiation of an input signal to the sampling-timing calibration unit;
• a multiplier adapted to multiply the conversion error signal and the sign of the time differentiation;
• and
• an accumulator integrating an output of the multiplier,
• wherein N is not divisible by M, and
• wherein each of the sampling-timing calibration units performs calibration by using an output of the accumulator.

An A/D converter comprising:

• M unitary A/D conversion units different in phase and equal in sampling rate, where M is an integer equal to or larger than 2, the A/D conversion units being connected in parallel;
• a reference A/D conversion unit connected in parallel to the M unitary A/D conversion units and having an operation clock frequency set to 1/N of an overall sampling rate of the A/D converter;
• and
• M calibration units each performing calibration at an output of a corresponding unitary A/D conversion unit, and each having a sampling-timing calibration unit adapted to correct an effective sampling timing of the corresponding unitary A/D conversion unit so as to be equal to an effective sampling timing of the reference A/D conversion unit,
• the effective sampling timing of the unitary A/D conversion unit and the reference A/D conversion unit is dependent on a sampling timing and an input-signal bandwidth of the unitary A/D conversion unit and the reference A/D conversion unit, respectively,
• wherein each of the sampling-timing calibration units comprises:
• a subtracting unit adapted to calculate a conversion error signal which is a difference between an output of the calibration unit and an output of the reference A/D conversion unit;
• a time differentiation deriving portion that derives a time differentiation of an input signal to the sampling-timing calibration unit;
• a multiplier adapted to multiply the conversion error signal and the time differentiation;
• and
• an accumulator integrating an output of the multiplier,
• wherein N is not divisible by M, and
• wherein each of the sampling-timing calibration units performs calibration by using an output of the accumulator.

An A/D converter comprising:

• M unitary A/D conversion units different in phase and equal in sampling rate, where M is an integer equal to or larger than 2, the A/D conversion units being connected in parallel;
• a reference A/D conversion unit connected in parallel to the M unitary A/D conversion units and having an operation clock frequency set to 1/N of an overall sampling rate of the A/D converter;
• and
• M calibration units each performing calibration at an output of a corresponding unitary A/D conversion unit, and each having a sampling-timing calibration unit adapted to correct an effective sampling timing of the corresponding unitary A/D conversion unit so as to be equal to an effective sampling timing of the reference A/D conversion unit,
• the effective sampling timing of the unitary A/D conversion unit and the reference A/D conversion unit is dependent on a sampling timing and an input-signal bandwidth of the unitary A/D conversion unit and the reference A/D conversion unit, respectively,
• wherein each of the sampling-timing calibration units comprises:
• a subtracting unit adapted to calculate a conversion error signal which is a difference between an output of the calibration unit and an output of the reference A/D conversion unit;
• a sign-of-time-differentiation deriving portion that derives a sign of a time differentiation of an input signal to the sampling-timing calibration unit;
• a multiplier adapted to multiply the conversion error signal and the sign of the time differentiation;
• and
• an accumulator integrating an output of the multiplier,
• wherein N is not divisible by M, and
• wherein each of the sampling-timing calibration units performs calibration by using an output of the accumulator.