JPH01176302A - Waveform equalizing circuit for recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the SN ratio of a signal component and to reduce a cost by connecting the grounding edge of a delay line to a first output terminal of a differential output amplifier and connecting the signal input terminal of the delay line to a second output terminal of the differential output amplifier. CONSTITUTION:A grounding edge 5 of a delay line 1 is connected to the first output terminal 6 of a differential output amplifier 3 and a signal input terminal 7 of the delay line 1 is connected the second output terminal 8 of the differential output amplifier. Accordingly, even when the differential output amplifier 3 is not composed of an operational amplifier or a filter is not provided in a current voltage terminal, the in-phase noise component is not converted to a differential noise component and an in-phase component can be outputted to the amplifier of a next step as the in-phase component. Thus, the SN of the signal component can be improved and the cost can be reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to this type of waveform equalization circuit.

[Conventional technology]

In high-density magnetic recording and reproducing devices, waveform equalization circuits have conventionally been used to increase the linear density of data.

Generally, a cosine equalization circuit as shown in Fig. 2 is used as a waveform equalization circuit, in which a delay line 1 and a resistor 2 whose characteristic impedance matches each other are connected in series, and a differential output amplifier is connected. By subtracting the composite waveform of the incident wave from the delay line 3 and the reflected wave from the delay line 1 from the output waveform of the open end 4 of the delay line 1 at a constant ratio, the tail area of the solitary wave is reduced.
It is designed to increase high frequency components.

Note that prior art related to this type of waveform equalization circuit is disclosed in, for example, Japanese Patent Application Laid-open Nos. 57-62426 and 58-039236.
It is stated in the No.

[Problem that the invention seeks to solve]

However, the conventional technique described above lacks consideration for common-mode component noise from the differential input signal and the power supply voltage. That is, according to the waveform equalization circuit shown in FIG. 2, the common-mode component of the differential input signal input to the amplifier 3 and the noise from the power supply voltage applied to the amplifier 3 are output as common-mode noise components. In FIG. 2, since the waveform equalization circuit is configured by the output of one side of the differential output amplifier 3, the common mode noise component becomes a differential noise component, and the S/N
was decreasing.

Note that as a measure to prevent the S/N from decreasing as described above, it is possible to configure the differential output amplifier 3 with an operational amplifier that can easily remove the common-mode component, or to provide a filter on the power supply voltage terminal, but both methods are the same. It is necessary to significantly reduce the phase signal component, and there is a drawback that an expensive S/N reduction prevention circuit is required.

The present invention has been made in consideration of the above points, and includes:
The purpose is to convert the common-mode noise component of the differential output amplifier into a differential noise component without configuring the differential output amplifier with an operational amplifier or installing a filter on the power supply voltage terminal. We aim to provide an economically inexpensive waveform equalization circuit for recording and reproducing devices, which not only improves the S/N of the signal component, but also allows the in-phase component to be output to the next stage amplifier as an in-phase component. It is something to do.

[Means for solving problems]

The purpose is to provide a recording medium for recording information, a head for recording or reproducing information by coming into close or soft contact with the surface of the recording medium, an amplifier for amplifying minute signals from the head, and at least one stage in the amplifier. In a recording/reproducing apparatus comprising a differential output amplifier connected to the differential output amplifier and a waveform equalization circuit connected after the differential output amplifier and utilizing a delay line for correcting the head output waveform, the ground end of the delay line is connected to the differential output amplifier. This is achieved by connecting the signal input terminal of the delay line to the first output terminal of the output amplifier and the second output terminal of the differential output amplifier.

[Effect]

According to the present invention having the above configuration, by connecting the ground end of the delay line to the differential output terminal, the common mode noise component of the differential output amplifier is The in-phase component is output to the next stage amplifier as an in-phase component without being converted into an output component.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings. FIG. 1 is an electrical wiring diagram showing one embodiment of a waveform equalization circuit according to the present invention.

In FIG. 1, the same symbols as those in the conventional waveform equalization circuit shown in FIG. 2 indicate the same parts, and the ground terminal 5 of the delay line 1 is connected to the first output terminal 6 of the differential output amplifier 3. ing.

Further, the input terminal 7 of the delay line 1 is connected to the second output terminal 8 of the differential output amplifier 3 via a resistor 2 with equal characteristic impedance, and the input of the next stage amplifier 9 is connected to the second output terminal 8 of the differential output amplifier 3. The signal is input from the tap end of a high-resistance variable resistor 10 connected between the open end 4, the input terminal 7 of the delay line 1, and the first output terminal 6 of the differential output amplifier 3.

According to the cosine equalization circuit shown in FIG. does not include a common-mode component, and only fluctuates at both terminals at the same time.The common-mode noise component of the differential output amplifier 3 is not converted into a differential noise component, but is passed through the next stage amplifier as a common-mode component. Therefore, according to the present invention, not only the S/N of the signal component can be improved, but also a special circuit for removing the in-phase component of the signal component, that is, the conventional expensive S/N reduction prevention measures can be used. Unlike other circuits, it is no longer necessary to configure the differential output amplifier with an operational amplifier or to provide a filter at the power supply voltage terminal.

In the illustrated embodiment, the present invention has been explained by taking a cosine equalization circuit as an example. Alternatively, if a plurality of equalization circuits are used, it is possible to obtain the same effect as described in the above embodiment.

Further, even if the differential output amplifier 3 is configured with a separate amplifier for each output, the same effect as in the embodiment described above can be obtained.

〔Effect of the invention〕

The present invention is as described above, and according to the present invention, the common mode noise component of the differential output amplifier can be reduced without configuring the differential output amplifier with an operational amplifier or without providing a filter on the power supply voltage terminal. without being converted into differential noise components.
The in-phase component can be output as an in-phase component to the next-stage amplifier, and not only can the S/N of the signal component be improved, but also an economically inexpensive waveform equalization circuit for a recording/reproducing device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram showing an embodiment of a waveform equalization circuit according to the present invention, and FIG. 2 is an electrical wiring diagram of a conventional waveform equalization circuit. DESCRIPTION OF SYMBOLS 1... Delay line, 2... Resistor, 3... Differential output amplifier, 9... Amplifier, 10... Variable resistor.

Claims (1)

[Claims] 1. A recording medium for recording information, a head for recording or reproducing information by coming into close or soft contact with the surface of the recording medium, an amplifier for amplifying minute signals from the head, and at least one stage connected within the amplifier. In a recording/reproducing apparatus comprising a differential output amplifier and a waveform equalization circuit connected after the differential output amplifier and using a delay line for correcting a head output waveform, the ground end of the delay line is connected to the differential output amplifier. A waveform equalization circuit for a recording/reproducing apparatus, characterized in that the signal input terminal of the delay line is connected to the first output terminal of the differential output amplifier.