KR100255212B1 - Circuit for generating asymmetriy radio frequency signal - Google Patents

Abstract

PURPOSE: A circuit for generating an asymmetric high frequency signal is provided to filter binary data to make an RF(Radio Frequency) signal, and to change a reference voltage of a binarization circuit to make a binary data section long or short, then to use an LPF(Low Pass Filter) to perform a filtering output. Therefore, it is possible to artificially generate the asymmetric RF signal, and to correctly estimate a reading capacity of an RF IC(Integrated Circuit). CONSTITUTION: The first filter(10) filters binary data, and outputs the binary data as a high frequency signal. A binarization circuit(20) performs a binarization for the high frequency signal by changing a reference voltage. The first filter(30) filters the data outputted from the binarization circuit(20), and outputs the filtered data as the high frequency signal.

Description

Asymmetric high frequency signal generation circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high frequency (RF) signal generation in an optical disc encoder, and more particularly, to an asymmetric high frequency signal generation circuit for adding an asymmetry to a general high frequency signal so as to correspond to an optical disc having an asymmetric pit.

Optical disc families such as compact discs (CDs) and digital video discs (DVDs) read data using the intensity of light reflected by the laser. The data reading process is performed through a high frequency (hereinafter referred to as RF) one-chip IC. In order to accurately evaluate the readability of the RF IC, an encoder system capable of generating an RF signal, which is an electrical signal reflected by a laser, without an optical disk is provided. It is essential. However, the conventional encoder merely generates an RF signal and does not produce asymmetric RF signals corresponding to a special optical disk. The special optical disk refers to an optical disk having an asymmetric pit. 1 illustrates an asymmetric fit generated in an actual optical disk. Assuming that (b) represents standard bits in FIG. 1, (a) is a shorter foot by a than standard bits, and (c) is a long foot by b than standard bits. As described above, an optical disk having an asymmetric pit is a phenomenon generally occurring in the manufacturing process. Therefore, in order to accurately evaluate the read performance of the RF IC, a circuit for generating an RF signal having an asymmetry corresponding to a special optical disk is required.

Accordingly, an object of the present invention is to provide an asymmetric RF signal generation circuit capable of responding to a special optical disk having an asymmetric pit in an optical disk encoder.

It is still another object of the present invention to provide an asymmetric RF signal generating circuit for generating an RF signal having an asymmetry so as to accurately evaluate the read performance of an RF one-chip IC of an optical disk reproducing apparatus.

The present invention for achieving the above object in the asymmetric high frequency signal generation circuit,

A first filter for filtering binary data and outputting the high frequency signal;

A binarization circuit for binarizing the filtered high frequency signal by changing a reference voltage;

And a second filter for filtering the data output from the binarization circuit and outputting the filtered data again as a high frequency signal.

1 illustrates asymmetric pits generated in an actual optical disk.

2 is an exemplary diagram of arbitrary binary data and corresponding high frequency signal waveforms used in an optical disk.

3 is a block diagram of an asymmetric high frequency signal generation circuit according to an embodiment of the present invention;

4 is an exemplary configuration diagram of the low pass filters 10 and 30 of FIG. 3.

5 is an output characteristic diagram of the low pass filter 10, 30 of FIG.

6 is an output waveform diagram of an asymmetric high frequency signal generation circuit having the configuration of FIG.

Hereinafter, an operation according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the following description and drawings, and detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

First, in order to make an RF signal in an optical disc encoder, the following process is required. In the first process, binary data used in the optical disk is produced, and in the second process, the data of the first process must be passed through a low pass filter having optical characteristics. 2 illustrates a signal waveform generated by such a process. 2 illustrates an arbitrary binary data and corresponding RF signal waveform diagram used in an optical disk. 2, (a), (b), and (c) show binary data A and corresponding RF signal waveforms B for pits having different periods, respectively. On the other hand, an actual optical disk may have asymmetry depending on the manufacturing state as described above. Since the optical disk has a structure in which the pits on the surface of the disk are long or short by a certain length, the RF signal to be reproduced has an asymmetry that is biased upward or downward rather than symmetrically. Therefore, in order to artificially make a signal having an asymmetry, a circuit that makes the binary data long or short by a certain period is required. This can be implemented by filtering binary data using a low pass filter and changing the reference voltage of the binarization circuit in the process of passing the filtered output RF signal through the binarization circuit.

3 is a block diagram of an asymmetric RF signal generation circuit according to an embodiment of the present invention. Referring to FIG. 3, the low pass filter 10 low-pass filters arbitrary binary data used in an optical disk and outputs the RF signal. That is, the low pass filter 10 serves to soften the output waveform so that the binary data can be applied to the binarization circuit 20. And the characteristic of the low pass filter 10 should just be comprised by the filter which has an optical characteristic mentioned later. The binarization circuit 20 outputs the RF signal artificially produced by the low pass filter 10 as binary data using a constant reference voltage E. At this time, by changing the reference voltage (E), since binary data is output as long or short by a certain length, it has characteristics similar to the surface of an optical disk having an asymmetric pit. Meanwhile, the low pass filter 30 having the optical characteristic filters the binary data output from the binarization circuit 20 and outputs the asymmetric RF signal.

FIG. 4 illustrates an exemplary configuration of the low pass filters 10 and 30 of FIG. 3, and illustrates a seventh-order Bessel filter including three secondary filters and one primary filter. As such, when the low pass filters 10 and 30 having the optical characteristics are implemented as a seventh-order Bessel filter, the binarized binary data may be output as an asymmetric RF signal. Looking at the transfer function H (s) of the second order filter is as shown in Equation 1 below.

FIG. 5 is a diagram illustrating output characteristics of the low pass filters 10 and 30 of FIG. 3, and FIG. 6 is a diagram illustrating an output waveform diagram of the asymmetric RF signal generation circuit having the configuration of FIG. 3. Hereinafter, a process of generating an asymmetric RF signal according to an embodiment of the present invention will be described with reference to FIGS. 3 and 6.

First, assuming that binary data generated to generate an RF signal having an asymmetry is as shown in a of FIG. 6, the RF signal waveform filtered through the low pass filter 10 is output as shown in F of FIG. 6. Subsequently, if the reference voltage E of the binarization circuit 20 is changed while the filtered RF signal F passes through the binarization circuit 20, binary data such as G of FIG. 6 is obtained. When binary data such as G of FIG. 6 is passed back to the low pass filter 30 having optical characteristics, an RF signal having an asymmetry is outputted to correspond to an optical disk having an asymmetric pit.

As described above, the present invention filters the binary data into an RF signal, changes the reference voltage of the binarization circuit to make the interval of the binary data long or short, and then filters the output using a low pass filter having optical characteristics. Asymmetrical RF signals with characteristics similar to the surface of optical disks can be produced. In addition, by using the asymmetric RF signal produced by the above-described process in the test of the RF one chip IC, the accuracy of the evaluation of the read performance of the RF one chip IC can be determined.

As described above, the present invention has an advantage of artificially generating an RF signal having an asymmetry that can actually occur in the optical disk, and as a result, it is possible to accurately evaluate the read performance of the RF IC of the optical disk reproducing apparatus. There is also an advantage.

Claims (3)

In the asymmetric high frequency signal generation circuit, A first filter for filtering binary data and outputting the high frequency signal; A binarization circuit for binarizing the filtered high frequency signal by changing a reference voltage; And a second filter for filtering the data output from the binarization circuit and outputting the filtered data as a high frequency signal. The asymmetric high frequency signal generation circuit of claim 1, wherein the first filter and the second filter are implemented as a Bessel filter. In the asymmetric high frequency signal generation circuit of an optical disc encoder, A first low pass filter for filtering EFM modulated or EFM plus modulated binary data and outputting the signal as a pepper wave signal; A binarization circuit for binarizing the high frequency signal by changing a reference voltage; And a second low pass filter for filtering the output signal of the binarization circuit to output a high frequency signal having asymmetry.

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