JPS583317A - Envelope tracking type slice level generating circuit - Google Patents

Abstract

PURPOSE:To decrease the error between a readout signal peak voltage and a slice level following to the envelope of the peak voltage from a magnetic recorder, by correcting the slice level through the use of a voltage comparator. CONSTITUTION:A readout signal is applied to a + input terminal of a voltage comparator 5, and the output is applied to a - input terminal via a diode 6 and a charging resistor 7. A capacitor 8 and a discharge resistor 9 are connected between the - input terminal and ground and a slice level in following to the envelope is obtained from the - input terminal. The comparator 5 compares the generated slice level with the peak voltage of the readout signal and the error is fed back, allowing to correct the slice level. Thus, the error between the peak voltage of the readout signal and the slice level following to the envelope can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an envelope-following slice level generation circuit, and particularly to a slice level generation circuit used in a read circuit of a magnetic recording device.

Conventionally, in a circuit that generates a slice level for detecting the level of a read signal of a magnetic recording device, as shown in FIG.
It consists of a capacitor 3 and a resistor 4 connected in parallel between the other layer of 2 and the ground.

A readout signal is applied to the anode terminal of diode l, and the peak voltage is charged to capacitor 3 with a time constant determined by resistor 2 and resistor 3, and discharge is performed with a time constant determined by capacitor 3 and resistor 4. The capacitor terminal voltage was set to a slice level that followed the envelope.

In the above circuit, there are problems such as level loss due to forward voltage drop of diode 1, and when applying a read signal to this circuit, the coupling condition of the signal source must be DC coupling and low impedance. There were some difficulties in using it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit that reduces the error between the peak voltage of a continuous signal and a slice level voltage that follows its envelope and has a high input impedance.

According to the present invention, a differential input voltage comparator is used, a read signal is applied to its positive input terminal, and the output of the voltage comparator is passed through a diode and a charging resistor to the negative input terminal of the voltage comparator. A slice level generation circuit that follows the curve from the negative input terminal is obtained by connecting a capacitor and a discharge resistor between the negative input terminal and ground.

The present invention uses a voltage comparator, and compares the output f: the slice level generated by integration with the peak voltage of the readout signal, and corrects the slice level by feeding back the error, resulting in less error. It also has high input impedance.

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 2, the embodiment of the present invention is a circuit for generating a pulse train by detecting the level of a read signal), which includes a voltage comparator 5 and a diode 6 connected to the positive output terminal of 5 on the anode side. and IjI! between the cathode side of 6 and the negative side output terminal of 5. a capacitor 8 and a variable resistor 9 connected between the negative input terminal of 5 and the ground;
Voltage comparator 10 connected by the sliding terminal and negative input terminal of
．． 11 and the NA connected to the negative output terminal of 10.11.
ND circuit 12 is included.

al and a2 are read signals of the magnetic recording device and are differential signals.

al is applied to the positive input terminal of voltage comparator 5.10,
a2 is applied to the positive input terminal of 11.

FIG. 3 shows the waveform of al. a2 is al as mentioned above
This is a waveform with the opposite polarity. al and a2 are subject to vibrational fluctuations.

Voltage comparator 5 compares the signal of al and the voltage of C,
For the time when al exceeds C, the pulse bt- shown in FIG.
Output.

The capacitor 8 is charged by the pulse b) with a time constant determined by the resistance value of the resistor 7. In the section where there is no pulse b,
The charge stored in the capacitor 8 is discharged through the resistor 9. The voltage C is generated by the nine repetitions of charging and discharging as described above, and has a waveform that follows the curve of the input read signal a1.

Voltage comparators 10 and 11 are used to detect the levels of al and a2.

What is the waveform of C? Since it is a slice level that follows the level of 1001 of 1, in order to increase the level detection margin, the voltage is divided by variable resistor 9, and the signal tone of d is generated.
applied to the negative input terminal of

e and f are negative pulse trains whose pulse width is the time when al and a2 exceed the voltage of d, respectively, and are ORed by the 12ONAND circuit to become a positive pulse train.

In this way, a slice level voltage with little error can be generated with respect to the peak voltage of the readout signal, stable level detection is possible, and the circuit to which the readout signal is applied is usually a voltage comparator with high input impedance. Therefore, it has the effect of being easy to drive.

As explained above, the present invention uses a voltage comparator to compare the peak voltage of an input read signal and the slice level created from the output of the voltage comparator, thereby reducing errors and reducing input impedance. It has the effect of increasing the

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional slice level generation circuit, Figure 2 is a circuit diagram showing an embodiment of the present invention, Figure 3 is an enlarged diagram.
2 is a time chart showing some waveforms in FIG. 2; 1...Diode, 2...Resistor, 3
......conde/su, 4...resistor, 5.
...Voltage comparator, 6...Diode, 7
...Resistor, 8...Condition/su, 9.
...Variable resistor, 10.11...Voltage comparator, 12...-NAND fan

Claims (1)

[Claims] It has a voltage comparator that outputs a signal 'ktB corresponding to the magnitude of the voltage applied to the first and second input terminals, and the output terminal of the voltage comparator is passed through a diode and the first resistor in series. , l! to the second input terminal of the voltage comparator. Knitting, 2nd
Connect a second resistor in parallel with a capacitor between the input terminal and ground of N! ! Next, an envelope following type slice level generator which applies a signal to the 11G1 input terminal of the voltage comparator and outputs multiple signals from the second input terminal.