KR100271616B1 - Apparatus and method for optimizing read channel in magnetic disk drive employed prml detection system - Google Patents

Abstract

PURPOSE: A device and method for optimizing a read channel of a magnetic disk driving device adopting a PRML(Partial Response Maximum Likelihood) detecting method is provided to control a programmable continuous time filter characteristic of a channel equalizer by feeding-back sampled data. Therefore, it is possible to optimize a PRML read channel. CONSTITUTION: A microprocessor(24) responds to sampled data outputted from a channel equalizer(4), and supplies a control value suitable for component characteristics of a magnetic head and a magnetic disk to the channel equalizer(4). On the basis of the control value, the channel equalizer(4) equalizes a magnetic signal in order to compensate the component characteristics of the magnetic disk and the magnetic head.

Description

APPARATUS AND METHOD FOR OPTIMIZING READ CHANNEL IN MAGNETIC DISK DRIVE EMPLOYED PRML DETECTION SYSTEM}

The present invention relates to a magnetic disk driving apparatus employing a Partial Response, Maximum Likelihood (PRML) detection method, and more particularly, to an apparatus and method for lead channel optimization.

These days, data storage and reading devices are rapidly increasing in capacity and evolved to allow high-speed data access. One example of such a data storage and reading device is a magnetic disk drive such as a hard disk drive (HDD). Such magnetic disk drives are widely used as auxiliary storage devices of computer systems because of their high density, high capacity, and high speed access. Until the magnetic disk drive device was realized to enable high capacity and high speed access, the design of the head / medium and the improvement of the manufacturing technology, the improvement of the servo technology, and the advance of the signal processing technology in the read and write channels were the factors. Among these factors, the signal processing technology is seeking a breakthrough in recent years by shifting from peak detection method to PRML (Partial Response, Maximum Likelihood) detection method.

The peak detection method is a technique commonly used in a magnetic disk drive device, and the PRML detection method is a technology applied to a magnetic disk drive device in recent years in order to realize high density, high capacity, and high speed. When these two technologies are applied to magnetic disk drive, the difference in signal processing is shown on the surface, while the peak detection method forms an analog channel for signal recording and reading, whereas the PRML detection method forms a digital channel for this purpose. Is that. PRML technology has been used in digital communications for many years, but now also applies to magnetic disk drives. Accordingly, in the lead channel using the PRML detection method applied to the magnetic disk driving device, the signal is sampled and digitized. When the functional operation is largely divided, the intersymbol interface caused by the increase in the linear density (InterSymbol Interface: ISI) ), Equalization to create the desired waveform with proper control, and sequence detection to recover data from the sampled data sequence using the Viterbi Algorithm.

1 shows a configuration of a lead channel (hereinafter referred to as a "PRML lead channel") employing a PRML detection method according to the prior art. A magnetic signal recorded on a recording medium made of magnetic disks is read through a magnetic head for signal recording and reading, and preamplified in a preamplifier and applied to an AGC (Automatic Gain Control Amplifier) 2 shown in FIG. do. In AGC amplifier 2, the gain of the signal is adjusted so that the input signal maintains a constant level of voltage. The output signal of the AGC amplifier 2 is applied to the programmable continuity time filter 6 of the channel equalizer 4, which is composed of a programmable continuous time filter 6 and an adaptive sampled data Finite Impulse Response filter 8. Programmable continuity time filter 6 typically consists of a continuous time 7-pole, 2 zero 0.05-degree phase equiripple filter, and a programmable asymmetric real zero for group delay equalization. It features asymmetrical real-axis zero, high frequency boost for programmable low-pass cutoff and pulse shaping. In the programmable continuity filter 6, the cutoff frequency and the boost value are set to remove noise of the signal and adjust the pulse width. The output signal of the programmable continuity time filter 6 is applied to the adaptive sample data FIR filter 8 in the channel equalizer 4. The adaptive sample data FIR filter 8 is generally composed of a sampled analog 5-tap transversal filter and samples the amplitude level of the signal according to a given sampling time and adjusts the adaptive filter coefficient value Km. Perform pulse equalization. The output signal of the adaptive sample data FIR filter 8 is a Viterbi detector 10, an 8/9 decoder 12, and a descrambler comprising an adaptive threshold qualifier and a survival sequence register. It is converted into NRZ data through 14.

In the PRML lead channel of such a magnetic disk drive device, pulse equalization is required to improve signal to noise ratio (SNR) and bit error rate (BER) by using inter-symbol interference (ISI) according to the pulse width of a signal. . However, because disc and head parts may have different characteristics, optimization of filter characteristics is necessary to compensate for this. However, referring to FIG. 1, when an error occurs in the read data applied to the Viterbi detector 10, a feedback component does not exist in the circuit configuration so that the condition of the FIR filter characteristic cannot be changed.

This PRML lead channel improves the read characteristics of the data compared to the conventional lead channel, but it is difficult to include the change factors according to the characteristics of the disk and the head in determining the adaptive filter coefficient value Km constant of the FIR filter. Therefore, if the Km constant is changed, the optimum condition of the FIR filter should be changed. However, the optimum condition cannot be changed because there is no component to be fed back.

Accordingly, an object of the present invention is to provide an apparatus and method for optimizing a read channel using a feedback component in a PRML lead channel.

According to the above object, the present invention is to adjust the characteristics of the filter of the channel equalizer to feed back the sampled data to satisfy the characteristics of the optimum FIR filter characteristics according to the characteristics of the head and disk. Headed.

1 is a block diagram of a lead channel employing the PRML detection method according to the prior art

2 is a block diagram of a lead channel employing a PRML detection method according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are denoted by the same reference numerals or the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

FIG. 2 is a block diagram of a PRML lead channel according to an embodiment of the present invention. In addition, a sampled signal feedback equalizer control unit 50 is added to the block diagram of FIG. 1 to optimize the PRML lead channel. It is further provided. The sample signal feedback equalization controller 50 recognizes the sampled data value to be fed back so as to satisfy the filter characteristic condition of the channel equalizer 4 optimally according to the component characteristics of the head and disk. The boost level of the programmable continuity time filter 6 included in the channel equalizer 4 is adjusted by providing a control value suitable for the characteristic.

The sample signal feedback equalization controller 50 of FIG. 2 includes a full wave rectifier 16, a low pass filer 18, an amplifier 20, an analog to digital converter 22, a microprocessor 24, and a digital to analog converter. ) Is composed of 26.

2, sampled data is output from the adaptive sample data FIR filter 8 of the channel equalizer 4, and the sampled data is output from the sample signal feedback equalizer 50. Full-wave rectification is performed by full-wave rectifier 16, and LPF 18 low-pass filters the output of full-wave rectifier 16. The output of LPF 18 is amplified by amplifier 20 and converted to a digital signal by ADC 22 and applied to microprocessor 24. The microprocessor 24 inputs the output of the ADC 22 (sampled data value to be fed back) and applies a control value for the current head and disk component characteristics to the programmable continuity time filter 6 through the DAC 26. Accordingly, the continuity time filter 6 adjusts (ie, resets) the boost level based on the control value. The programmable continuity time filter 6 in the channel equalizer 6 has a programmable asymmetric real axis zero function for group delay equalization, a programmable low pass cutoff frequency and a high pass boost function for pulse shaping, as described with reference to FIG. A boost value is set, and the boost value set by the control value according to an embodiment of the present invention is level adjusted to compensate for the current magnetic disk and magnetic head component characteristics.

As a result, the component characteristics according to the magnetic disk and the magnetic head are compensated, thereby optimizing the filter characteristics of the channel equalizer 4. This results in optimization of the PRML lead channel.

In the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the equality of the claims and the claims.

As described above, the present invention adjusts the programmable continuity time filter characteristic of the channel equalizer by feeding back sampled data to satisfy the filter characteristic condition of the optimal channel equalizer according to the characteristics of the head and disk. There is an advantage that optimization is made.

Claims (4)

Lead channel optimization in a magnetic disk drive system employing a PRML detection method including a channel equalizer for equalizing a signal to provide a desired waveform by controlling interference between symbols by inputting a magnetic signal read from the magnetic disk by a magnetic head. In the method for Providing a control value corresponding to the component characteristics of the magnetic head and the magnetic disk to the channel equalizer in response to the sampled data output from the channel equalizer; And the channel equalizing unit equalizes the magnetic signal to compensate for magnetic disk and magnetic head component characteristics based on the control value. An apparatus for optimizing lead channels of a magnetic disk drive apparatus employing a PRML detection method, The magnetic signal read out from the magnetic disk by the magnetic head is input to control the intersymbol interference so that the magnetic signal is compensated to compensate for the characteristics of the magnetic disk and the magnetic head components based on the control value provided to equalize the desired waveform. A channel equalizer to equalize, And a feedback equalization control unit for providing the channel equalizer with control values corresponding to the component characteristics of the magnetic head and the magnetic disk in response to the sampled data output from the channel equalizer. 3. The channel equalizer of claim 2, wherein the channel equalizer Programmable asymmetric real axis zero function for group delay equalization, programmable low pass cutoff frequency and high pass boost function for pulse shopping, cutoff frequency and boost value are set, and the set boost value is the current magnetic disk. And a programmable continuity time filter level adjusted to compensate for magnetic head component characteristics; And an adaptive FIR filter for pulse equalizing the output of the programmable continuity time filter. The method of claim 3, wherein the feedback control unit A full-wave rectifier for full-wave rectifying the sampled data output from the adaptive FIR filter; A low pass filter for low pass filtering the output of the full wave rectifier; And a controller for providing the programmable continuity time filter with a control value corresponding to the component characteristics of the magnetic head and the magnetic disk in response to the output of the low pass filter.

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