JP4804268B2 - Digital PLL circuit and data reproducing apparatus - Google Patents

Description

  The present invention is a digital PLL (Phase PLL) that performs interpolation processing based on phase information on digital data sampled with a fixed clock and A / D (Analog to Digital) converted to obtain sample data at a regular sampling timing. The present invention relates to a data reproduction apparatus for demodulating sample data acquired by the PLL circuit and acquiring reproduction data by demodulating the sample data acquired by the PLL circuit.

  Conventionally, an analog PLL circuit has been used as a PLL circuit of a disk reproducing apparatus. However, an analog PLL circuit is susceptible to noise and has a drawback of being vulnerable to environmental changes such as temperature changes. On the other hand, the digital PLL circuit is not easily affected by noise, and the characteristics are hardly affected by environmental changes such as temperature changes. Further, it has an advantage that it is easy to achieve high integration and is advantageous when mounted on an LSI.

  FIG. 7 shows an example of the configuration of a disk reproducing apparatus incorporating an ITR (Interpolated Timing Recovery) type digital PLL circuit.

  An optical disc apparatus according to this configuration example includes an optical pickup 101, an amplifier circuit 102, an ADC (Analog-Digital Converter) 103, a data interpolation circuit 104, an equalizer 105, a Viterbi decoder 106, a phase comparator 107, An LPF (loop filter) 108 and a digital VCO (Voltage Controlled Oscillator) 109 are provided.

  The optical pickup 101 irradiates a disk with laser light to write data and receives reflected light from the disk to read data. The amplification circuit 102 amplifies the reproduction RF signal supplied from the optical pickup 101 and outputs it to the ADC 103. The ADC 103 samples the reproduction RF signal in accordance with a high-frequency asynchronous clock (system clock) supplied from an oscillation circuit (not shown), converts the sample value into digital data (AD data), and sends it to the data interpolation circuit 104. Output.

  The data interpolation circuit 104 calculates the data value (resample data) at the data interpolation timing (resample timing) using the AD data input from the ADC 103 and the phase information input from the digital VCO 109, and calculates the calculated resample data. Sample data is output to the equalizer 105.

  The equalizer 105 performs waveform equalization processing on the resampled data supplied from the data interpolation circuit 104 and outputs the result to the Viterbi decoder 106. The Viterbi decoder 106 performs Viterbi decoding processing on the digital data supplied from the equalizer 105 to generate and output binary data of 1 and 0.

  Based on the resample data supplied from the data interpolation circuit 104, the phase comparator 107 detects the phase difference (ΔP) between the resample timing supplied from the digital VCO 109 and the normal resample timing, Output to the LPF 108. The LPF 108 cuts off the high frequency component of the phase difference (ΔP) and converts it into a direct current, which is output to the digital VCO 109.

The digital VCO 109 adjusts the resample timing based on the DC data supplied from the LPF 108 so as to approach the normal resample timing, and supplies phase information that defines the adjusted resample timing to the data interpolation circuit 104. Output.
Japanese Patent No. 3687425

  With the recent increase in the density of optical disks, Viterbi decoding using PRML (Partial Response Maximum Likelihood) has been widely adopted as a reproduction signal processing method in optical disk drives. In addition, there are optical discs adopting different PRMLs on the market, and therefore, an optical disc drive is required to have a function to cope with optical discs having different PRMLs.

  However, when the PRML is different, for example, as shown in FIG. 8, the data interpolation point (resample point: indicated by a black circle in FIG. 8) may be different. For this reason, when trying to support optical disks with different PRML, For example, it is necessary to prepare a PLL circuit for each PRML and to supply phase information suitable for the PRML from the PLL circuit corresponding to the PRML of the optical disk when reproducing the optical disk. However, in this case, a plurality of PLL circuits must be prepared, which causes a problem that the circuit scale increases.

  Accordingly, an object of the present invention is to provide a digital PLL circuit that can smoothly cope with different PRMLs while suppressing an increase in circuit scale, and a data reproducing apparatus that employs the digital PLL circuit.

  In view of the above problems, the present invention has the following features.

  According to a first aspect of the present invention, there is provided a digital PLL circuit that obtains sample data at a regular sampling timing by performing interpolation processing based on phase information on digital data sampled by a fixed clock and A / D converted. A first data interpolation circuit for performing interpolation on data, and phase information generation for generating first phase information for the first data interpolation circuit based on sample data generated by the first data interpolation circuit A circuit, a phase adjustment circuit for generating second phase information by changing the phase of the first phase information by a fixed phase amount, and interpolation processing for the digital data based on the second phase information And a second data interpolation circuit for performing the operation.

  According to a second aspect of the present invention, in the digital PLL circuit according to the first aspect, the phase adjustment circuit includes a phase difference between an interpolation timing in the first data interpolation circuit and an interpolation timing in the second data interpolation circuit. The second phase information is generated by changing the phase of the first phase information by a phase amount corresponding to.

  According to a third aspect of the present invention, there is provided a digital PLL circuit that obtains sample data at a regular sampling timing by performing interpolation processing based on phase information on A / D (converted digital data) sampled with a fixed clock. A first data interpolation circuit for performing interpolation processing according to the first PRML on the digital data, and generating first phase information according to the first PRML based on the sample data generated by the first data interpolation circuit A phase information generation circuit that supplies the first data interpolation circuit; a second data interpolation circuit that performs interpolation processing on the digital data according to a second PRML at an interpolation timing different from the first PRML; Between the interpolation timing in the first PRML and the interpolation timing in the second PRML And having a phase amount by the first second generating phase information by changing the phase of the phase information and the second data interpolation circuit which supplies a phase adjustment circuit according to the phase difference.

  According to a fourth aspect of the present invention, the digital data sampled with a fixed clock and A / D converted is subjected to interpolation processing based on phase information to acquire sample data at a regular sampling timing, and the acquired sample data is demodulated. A first data interpolation circuit that performs an interpolation process on the digital data, and a first data interpolation circuit based on sample data generated by the first data interpolation circuit. Based on a phase information generation circuit that generates phase information, a phase adjustment circuit that generates second phase information by changing the phase of the first phase information by a certain phase amount, and the second phase information Generated by a second data interpolation circuit that performs interpolation processing on the digital data, and the first and second data interpolation circuits. And having a decoding circuit for generating binary data from the sample data.

  According to a fifth aspect of the present invention, in the data reproducing apparatus according to the fourth aspect, the phase adjustment circuit includes a phase difference between an interpolation timing in the first data interpolation circuit and an interpolation timing in the second data interpolation circuit. The second phase information is generated by changing the phase of the first phase information by a phase amount corresponding to.

  According to a sixth aspect of the present invention, in the data reproduction device according to the fourth or fifth aspect, the decoding circuit generates a first binarized data from the sample data generated by the first data interpolation circuit. A decoding unit and a second decoding unit that generates binarized data from the sample data generated by the second data interpolation circuit are provided.

  According to the seventh aspect of the invention, the digital data sampled with the fixed clock and A / D converted is subjected to the interpolation processing based on the phase information to acquire the sample data at the normal sampling timing, and the acquired sample data is demodulated. A first data interpolation circuit that performs an interpolation process on the digital data in accordance with a first PRML, and a sample data generated by the first data interpolation circuit in accordance with the first PRML. A phase information generation circuit that generates first phase information and supplies the first phase information to the first data interpolation circuit; and a second that performs interpolation processing on the digital data according to a second PRML at an interpolation timing different from the first PRML. Data interpolation circuit, interpolation timing in the first PRML, and the second PRML A phase adjustment circuit that generates second phase information by changing the phase of the first phase information by a phase amount corresponding to a phase difference between interpolation timings and supplies the second phase information to the second data interpolation circuit; And a decoding circuit that generates binarized data from the sample data generated by the first and second data interpolation circuits.

  According to an eighth aspect of the present invention, in the data reproduction device according to the seventh aspect, the decoding circuit generates a binarized data from the sample data generated by the first data interpolation circuit. And a second decoding unit that generates binarized data from the sample data generated by the second data interpolation circuit.

  According to the first to third aspects of the present invention, it is possible to smoothly reproduce a disc conforming to a different PRML. Further, since the phase information generated by the phase information generation circuit according to the first PRML is used for processing according to the second PRML, there is no need to separately arrange the phase information generation circuit according to the second PRML, An increase in circuit scale can be suppressed. Furthermore, the phase information generated by the phase adjustment circuit is obtained by calculating the phase of the phase information according to the first PRML generated by the phase information generation circuit between the interpolation timing in the first PRML and the interpolation timing in the second PRML. The phase information generated by the phase adjustment circuit is the second PRML as apparent from the relationship of the sample points shown in FIG. 8, for example. It is suitable for performing processing according to the above. Therefore, even when the phase information generated by the phase adjustment circuit in this way is used when performing processing according to the second PRML, the processing according to the second PRML can be performed with high accuracy.

  As described above, according to the present embodiment, it is possible to smoothly and accurately reproduce the disc according to the first and second PRML while suppressing an increase in circuit scale.

  According to a fourth aspect of the present invention, there is provided a data reproducing apparatus having the configuration of the digital PLL circuit according to the first aspect of the present invention. Therefore, according to the inventions of claims 4 to 8, the same effects as those of the inventions of claims 1 to 3 can be obtained.

  The features of the present invention will become more apparent from the following description of embodiments.

However, the following embodiment is merely an exemplary form for implementing the present invention, and the meaning of the terminology of the present invention or each constituent element is as described in the following embodiment. It is not limited.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration of a disc reproducing apparatus according to the embodiment. In the figure, the same parts as those shown in FIG.

  The disc reproducing apparatus shown in FIG. 1 can deal with both optical discs according to PR (1, 2, 2, 2, 1) and optical discs according to PR (1, 2, 2, 1). In the figure, a circuit comprising a data interpolation circuit 104, an equalizer 105, a Viterbi decoder 106, a phase comparator 107, an LPF 108, and a digital VCO 109 corresponds to an optical disc according to PR (1, 2, 2, 2, 1) shown in the lower part of FIG. Is a signal processing system for supporting an optical disc conforming to PR (1, 2, 2, 1) shown in the upper part of FIG. 8. The circuit including the data interpolation circuit 110, the equalizer 111, and the Viterbi decoder 112 is a signal processing system. It is.

  Compared with the configuration of FIG. 8, the data reproducing circuit 110, the equalizer 111, the Viterbi decoder 112, and the phase adjusting circuit 113 are added to the disk reproducing apparatus according to the present embodiment.

The data interpolation circuit 110 uses the AD data input from the ADC 103 and the phase information input from the phase adjustment circuit 113 to calculate a data value (resample data) at the resample timing, and the calculated resample data is calculated. Output to the equalizer 111.

  The equalizer 111 performs waveform equalization processing on the input resample data and outputs the result to the Viterbi decoder 112. The Viterbi decoder 112 performs Viterbi decoding processing on the digital data supplied from the equalizer 111 to generate and output binary data of 1 and 0.

  The phase adjustment circuit 113 performs phase adjustment processing on the phase information output from the digital VCO 109 and outputs the adjusted phase information to the data interpolation circuit 110. Specifically, the phase of the phase information output from the digital VCO 109 is delayed by 180 °, and the delayed phase information is output to the data interpolation circuit 110.

  FIG. 2 is a diagram for explaining specific processing in the phase comparator 107.

  As shown in the figure, the phase comparator 107 discriminates the edge of the reproduction signal waveform, that is, the intersection position of the reproduction signal waveform and the slice level (zero level) based on the resampled data supplied from the data interpolation circuit 104. The phase difference (ΔP) between the determined edge position and the intermediate timing of the resample timing before and after the detected edge is detected and output to the LPF 108.

  The LPF 108 cuts off the high frequency component of the input phase difference (ΔP) and converts it into a direct current, which is output to the digital VCO 109. The digital VCO 109 adjusts the resample timing so as to compensate for the phase difference of the edge in accordance with the DC data supplied from the LPF 108, and sends phase information that defines the adjusted resample timing to the data interpolation circuit 104. Output.

  FIG. 3 is a diagram for explaining processing in the data interpolation circuit 104. In the figure, the A / D clock is a sampling clock (asynchronous clock) in the ADC 103.

  As shown in the figure, the data interpolation circuit 104 obtains a phase difference PH0 between the resample timing defined by the phase information and the sampling timing of the digital data that comes immediately after that, and sandwiches this PH0 and the resample timing. A data value (resample data) at the resample timing is calculated from the sampling data before and after. For example, taking an interpolation process between the digital data D2 and D3 as an example, the phase difference PH0 between the resample timing in the interpolation process and the sampling timing of D3 is obtained. Then, using the values of D2 and D3, the phase difference PH0, and the period PH1 of the A / D clock, X is obtained by the proportional calculation shown in the upper left of the figure, and the obtained X is added to D2, Resample data at the sample timing is obtained.

  The processing shown in FIG. 3 is performed similarly in the data interpolation circuit 110. However, since the data interpolation circuit 110 performs processing according to PR (1, 2, 2, 1) in the upper stage of FIG. 8 as described above, PR (1, 2, 2, 2) supplied from the digital VCO 109 is used. If the resample timing is set based on the phase information according to (2) and (1), the resample data cannot be acquired at the correct resample timing.

  In the present embodiment, the phase information supplied from the digital VCO 109 is converted into phase information suitable for PRML of the data interpolation circuit 110 by the phase adjustment circuit 113 and supplied to the data interpolation circuit 113. Specifically, the phase of the phase information supplied from the digital VCO 109 is delayed by 180 ° and then supplied to the data interpolation circuit 110.

  Referring to FIG. 8, the resample timing is shifted by 180 ° between PR (1, 2, 2, 1) and PR (1, 2, 2, 2, 1). Therefore, the resampling timing corresponding to PR (1, 2, 2, 1) is generated by shifting the phase of the resampling timing generated according to PR (1, 2, 2, 2, 1) by 180 °. Can do. In the phase adjustment circuit 113, 180 ° is added to the phase of the phase information corresponding to PR (1, 2, 2, 2, 1) supplied from the digital VCO 109. Thereby, phase information suitable for PR (1, 2, 2, 1) is generated.

  FIG. 4 is a diagram showing the relationship between the reproduction RF signal and the resample timing. In the figure, “Resample timing A” is according to PR (1, 2, 2, 2, 1), and “Resample timing B” is according to PR (1, 2, 2, 1). Resample timing.

  In the data interpolation circuit 104, resample data is generated at the timing of the resample timing A according to the phase information from the digital VCO 109. In the data interpolation circuit 110, resample data is generated at the timing of the resample timing B in accordance with the phase information after the phase information from the digital VCO 109 is delayed by 180 ° by the phase adjustment circuit 113.

  Thus, in the present embodiment, the interpolation processing according to PR (1, 2, 2, 2, 1) and the interpolation processing according to PR (1, 2, 2, 1) are performed in parallel on the reproduced signal waveform. Done. Then, the resampled data generated according to PR (1, 2, 2, 2, 1) is processed by the equalizer 105 and the Viterbi decoder 106 to generate binary data of 1 and 0. Also, the resampled data generated according to PR (1, 2, 2, 1) is processed by the equalizer 111 and the Viterbi decoder 112 to generate binary data of 1 and 0.

  The binarized data output from the Viterbi decoders 106 and 112 are respectively input to corresponding demodulation circuits (not shown). Each demodulation circuit performs demodulation processing according to the signal format of the corresponding optical disk.

  Note that which demodulation circuit is used is determined in accordance with, for example, the type discrimination of the optical disk. Here, the reproduction target discs are HD (High Definition DVD) and BD (Blu-ray Disc). For example, PR (1, 2, 2, 2, 1) is applied to HD, and PR (1, 1, 2) is applied to BD. 2, 2, 1) is applied, the type of the optical disc can be discriminated by, for example, comparing the amount of return light when the optical disc is irradiated with laser light. If the discrimination result is HD, PR When the demodulating circuit for demodulating the binarized data from the Viterbi decoder 106 according to (1, 2, 2, 2, 1) is selected and the discrimination result is BD, PR (1, 2, 2, 1 The demodulating circuit that demodulates the binarized data from the Viterbi decoder 112 is selected.

  As described above, according to the present embodiment, two types of discs according to PR (1, 2, 2, 2, 1) and PR (1, 2, 2, 1) can be smoothly reproduced. Further, in order to use the phase information generated by the PLL circuit according to PR (1, 2, 2, 2, 1) for processing according to PR (1, 2, 2, 1), PR (1, 2, 2, 1) It is not necessary to separately provide a PLL circuit according to 1), and thus an increase in circuit scale can be suppressed. Furthermore, the phase information for PR (1, 2, 2, 1) is generated by delaying the phase of the phase information generated by the PLL circuit according to PR (1, 2, 2, 2, 1) by 180 °. Therefore, as is apparent with reference to the relationship between the sample points shown in FIG. 8, the PR (1, 2, 2, 1) process can be performed with high accuracy.

  Thus, according to the present embodiment, two types of discs according to PR (1, 2, 2, 2, 1) and PR (1, 2, 2, 1) are suppressed while suppressing an increase in circuit scale. Reproduction can be performed smoothly and accurately.

  Although the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above, and various other modifications are possible.

  For example, in the above embodiment, the phase of the phase information generated by the PLL circuit according to PR (1, 2, 2, 2, 1) is delayed by 180 ° and is suitable for PR (1, 2, 2, 1). Although the phase information is generated, the phase of the phase information generated by the PLL circuit according to PR (1, 2, 2, 1) is delayed by 180 ° to PR (1, 2, 2, 2, 1). Phase information suitable for the above may be generated.

  In the above-described embodiment, the decoding system including the equalizer 105 and the Viterbi decoder 106 and the decoding system including the equalizer 111 and the Viterbi decoder 112 are individually arranged on the subsequent stage side of the data interpolation circuits 104 and 110, respectively. As shown in FIG. 5, the equalizer 121 may be shared. Here, as the equalizer 121, a so-called adaptive equalizer in which tap coefficients are adjusted according to the processing results in the Viterbi decoders 106 and 112 can be used. Or you may use the equalizer which can set a tap coefficient suitably according to which Viterbi decoder is used. Note that 120 is a switching circuit for selecting the output of the data interpolation circuits 104 and 110, and 122 is a switching circuit for allocating the output of the equalizer 121 to the Viterbi decoders 106 and 112. Thus, by sharing the equalizer 121, it is possible to further suppress an increase in circuit scale.

  Further, in the above embodiment, the phase of the resample timing of PR (1, 2, 2, 2, 1) and PR (1, 2, 2, 1) is shifted by 180 ° as shown in FIG. Although the phase adjustment amount Δα in the phase adjustment circuit 113 is set to 180 °, when the phase shift of the resample timing is other than 180 °, the phase adjustment amount Δα may be changed accordingly.

  When it is necessary to set a plurality of phase adjustment amounts, for example, as shown in FIG. 6, a plurality of phase adjustment circuits 133 and 134 are arranged, and in accordance with this, the data interpolation circuit 130, the equalizer 131 and the Viterbi decoder are arranged. 132 may be added. In the configuration example of FIG. 6 as well, as in the case of FIG. 5 described above, the switching circuit 120 may be provided to share the equalizer and the Viterbi decoder.

  In addition, in the above-described embodiment, the case of reproducing a disc according to PR (1, 2, 2, 2, 1) and PR (1, 2, 2, 1) has been described. However, the present invention is not limited to this. The present invention can also be applied to a reproducing apparatus that reproduces a disc according to PRML. Further, the present invention is not limited to the optical disc but can be applied to the case of reproducing other recording media.

  The present invention is not limited to the above embodiment. The embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

The figure which shows the structure of the disc reproducing | regenerating apparatus concerning embodiment The figure explaining operation | movement of the phase comparator which concerns on embodiment The figure explaining operation | movement of the data interpolation circuit which concerns on embodiment The figure which shows the relationship between the reproduction signal and resample timing which concern on embodiment The figure which shows the example of a change of the disc reproducing | regenerating apparatus concerning embodiment The figure which shows the example of a change of the disc reproducing | regenerating apparatus concerning embodiment The figure which shows the structure of the disc player concerning a prior art example The figure which shows the resample point in PR (1, 2, 2, 2, 1) and PR (1, 2, 2, 1)

Explanation of symbols

104 Data interpolation circuit (first data interpolation circuit)
105 Equalizer (first decoding unit)
106 Viterbi decoder (first decoding unit)
107 phase comparator (phase information generation circuit)
108 LPF (Phase information generation circuit)
109 Digital VCO (Phase information generator)
110 Data interpolation circuit (second data interpolation circuit)
111 equalizer (second decoding unit)
112 Viterbi decoder (second decoding unit)
113 phase adjustment circuit 121 equalizer (first and second decoding units)
130 Data interpolation circuit (second data interpolation circuit)
131 equalizer (second decoding unit)
132 Viterbi decoder (second decoding unit)

Claims (8)

In a digital PLL circuit that performs interpolation processing based on phase information on digital data sampled at a fixed clock and converted from analog to digital (A / D), and obtains sample data at regular sampling timing.
A first data interpolation circuit for performing interpolation processing on the digital data;
A phase information generation circuit for generating first phase information for the first data interpolation circuit based on the sample data generated by the first data interpolation circuit;
A phase adjustment circuit for generating second phase information by changing the phase of the first phase information by a fixed phase amount;
A second data interpolation circuit that performs an interpolation process on the digital data based on the second phase information,
A digital PLL circuit characterized by that. The digital PLL circuit according to claim 1,
The phase adjustment circuit changes the phase of the first phase information by a phase amount corresponding to the phase difference between the interpolation timing in the first data interpolation circuit and the interpolation timing in the second data interpolation circuit. Generating second phase information;
A digital PLL circuit characterized by that. In a digital PLL circuit that performs interpolation processing based on phase information on digital data sampled at a fixed clock and converted from analog to digital (A / D), and obtains sample data at regular sampling timing.
A first data interpolation circuit for performing an interpolation process on the digital data according to a first PRML (Partial Response Maximum Likelihood);
A phase information generation circuit that generates first phase information according to the first PRML based on the sample data generated by the first data interpolation circuit and supplies the first phase information to the first data interpolation circuit;
A second data interpolation circuit that performs an interpolation process on the digital data according to a second PRML at an interpolation timing different from the first PRML;
The second phase information is generated by changing the phase of the first phase information by a phase amount corresponding to the phase difference between the interpolation timing in the first PRML and the interpolation timing in the second PRML. A phase adjustment circuit that supplies the data interpolation circuit
A digital PLL circuit characterized by that. Data that is sampled at a fixed clock and A / D (Analog to Digital) converted digital data is subjected to interpolation processing based on phase information to obtain sample data at a regular sampling timing and to demodulate the obtained sample data In the playback device,
A first data interpolation circuit for performing interpolation processing on the digital data;
A phase information generation circuit for generating first phase information for the first data interpolation circuit based on the sample data generated by the first data interpolation circuit;
A phase adjustment circuit for generating second phase information by changing the phase of the first phase information by a fixed phase amount;
A second data interpolation circuit that performs an interpolation process on the digital data based on the second phase information;
A decoding circuit that generates binarized data from the sample data generated by the first and second data interpolation circuits,
A data reproducing apparatus characterized by that. The data reproducing apparatus according to claim 4, wherein
The phase adjustment circuit changes the phase of the first phase information by a phase amount corresponding to the phase difference between the interpolation timing in the first data interpolation circuit and the interpolation timing in the second data interpolation circuit. Generating second phase information;
A data reproducing apparatus characterized by that. The data reproducing apparatus according to claim 4 or 5,
The decoding circuit includes a first decoding unit that generates binarized data from the sample data generated by the first data interpolation circuit, and two samples from the sample data generated by the second data interpolation circuit. A second decoding unit that generates the quantified data,
A data reproducing apparatus characterized by that. Data that is sampled at a fixed clock and A / D (Analog to Digital) converted digital data is subjected to interpolation processing based on phase information to obtain sample data at a regular sampling timing and to demodulate the obtained sample data In the playback device,
A first data interpolation circuit for performing an interpolation process on the digital data according to a first PRML (Partial Response Maximum Likelihood);
A phase information generation circuit that generates first phase information according to the first PRML based on the sample data generated by the first data interpolation circuit and supplies the first phase information to the first data interpolation circuit;
A second data interpolation circuit that performs an interpolation process on the digital data according to a second PRML at an interpolation timing different from the first PRML;
The second phase information is generated by changing the phase of the first phase information by a phase amount corresponding to the phase difference between the interpolation timing in the first PRML and the interpolation timing in the second PRML. A phase adjustment circuit to be supplied to the data interpolation circuit of
A decoding circuit that generates binarized data from the sample data generated by the first and second data interpolation circuits,
A data reproducing apparatus characterized by that. The data reproducing apparatus according to claim 7, wherein
The decoding circuit includes a first decoding unit that generates binarized data from the sample data generated by the first data interpolation circuit, and two samples from the sample data generated by the second data interpolation circuit. A second decoding unit that generates the quantified data,
A data reproducing apparatus characterized by that.

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