JPS5928721A - Detecting circuit of continuous alternating signal peak value - Google Patents

Abstract

PURPOSE:To detect a peak value of a continuous AC signal with high accuracy and good linearity, by providing a comparator, a monostable multivibrator and an integrating circuit and the like to a level comparison circuit of a continuous AC signal peak value detecting circuit so as to detect the peak value up to a high frequency region. CONSTITUTION:An input continuous AC signal 1 is applied to a level comparison circuit 9, the signal is compared with an analog signal 4 from a D/A converter 11, and when the level of the analog signal 4 is higher than the level of the signal 1, an output 13 is applied to an up-down counter 10. A clock signal 12 is inputted to the counter 10, an output from the counter 10 is applied to the D/A converter 11 to detect the peak value of the signal 1. This comparison circuit 9 is constituted of the comparator 14 and the monostable multivibrator 15 or the comparator 14, the integrating device 16 and the 2nd comparator 17. Further, the level of the analog signal 4 is made almost equal to the peak value of the signal 1, the peak value is detected up to a high frequency region and the peak value of the signal 1 is detected with high accuracy and good linearity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous alternating current signal peak value detection circuit used for envelope detection, output value detection, etc. of recording/reproduction output in a magnetic disk inspection apparatus.

Conventionally, as a circuit for detecting the envelope of recording and reproducing output in a magnetic disk inspection device, as shown in the block diagram in FIG. A configuration was used in which an analog output 4 having the same level as the input signal amplitude was obtained by dividing the input signal by s. As the rectifier circuit 2, as shown in FIG. 2, a circuit utilizing nonlinearity between the base and emitter of a transistor 5.6 has often been used. However, when using this rectifier circuit, the linearity of the input signal peak value versus output level is poor, especially for low-level signals, and in magnetic disk inspection equipment, the input signal peak value corresponding to the recording and playback output is at a low level. There is a drawback that the inspection accuracy deteriorates when the variation range is large from 1 to 3. Further, as a rectifier circuit with good linearity of input signal peak value versus output level, a rectifier circuit using a diode 7 and an operational amplifier 8 as shown in FIG. 3 was also often used. However, due to the limits of the frequency characteristics of operational amplifiers, this circuit does not operate correctly for signals with high frequencies of J) l QM) lz or higher, and cannot cope with the increasing density and frequency of magnetic disk drives. It's here.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional circuits and provide a continuous AC signal peak value detection circuit that detects the peak value of a continuous AC signal such as the recording/reproduction output of a magnetic disk with good linearity in a high frequency range. There is a particular thing.

The continuous AC signal peak value detection circuit according to the present invention includes a DA converter that converts a digital signal into an analog signal, a level comparison circuit that compares the analog signal with the peak value of an input continuous AC signal, and the level comparison circuit. and an up/down counter that outputs the digital signal by controlling the power of the clock signal and outputting the digital signal, and the level of the analog signal is equal to the peak value of the input continuous countercurrent signal. It is assumed that the temples are composed so that they are almost equal.

Hereinafter, embodiments of the present invention will be explained based on the drawings.

Fig. 4 shows continuous alternating jlf and signal peak value detection +I according to the present invention.
This is an embodiment of the + circuit, with 9 indicating a level comparison circuit, 10 an up/down counter, and an 11-digit DA converter.

In addition, FIG. 5 is a waveform diagram for explaining the operation of the circuit. In these diagrams, the peak value of the input continuous AC signal 1 and the analog output DC voltage 4 of the DA converter are shown.
is compared in a level comparison circuit 9, and an output 13 is obtained in which when the DC voltage output 4 is larger than the wave bottom value of the input continuous AC signal 18, it is at a high level, and when it is smaller, it is at a low level.

As an example of this level comparison circuit 9, as shown in FIG.
It is possible to use a circuit configured with four circuits or a circuit configured with a comparator 14, an integrating circuit 16, and a second comparator 17 as shown in FIG. Output 1 of level comparison circuit 9
When 3 is high level, amp down counter 10
The clock signal 12 is decremented by the clock signal 12, and when it is at a low level, the power is decreased by the number η1. 1 White current' city pressure output.

With the circuit having such a configuration, when the level of the analog output 4 of the DA converter 11 is higher than the peak value of the input continuous AC signal 10, the output of the level comparison circuit 9 becomes high level,
The digital output of the up/down counter 10 gradually decreases, and the level of the analog output 40 of the DA converter 11 gradually decreases accordingly. Conversely, when the analog output of the DA converter 11 is at 40 levels, or when the continuous AC signal is less than 10 wave heights, the output of the level comparison circuit 9 becomes a low level, and the digital output of the amplifier/town counter 10 gradually increases. DA converter 1 according to this
The analog output 40 level of the input AC signal 1 gradually increases to υ, and eventually balance is maintained when the peak value of the input AC signal 1 and the analog output 40 level of the DA converter 11 become equal.

Considering the stability and response speed of the circuit, it is desirable that the frequency of the clock signal 120 is about the same as the frequency of the input AC signal 10, but it may be lower than the frequency of the input AC signal if the response speed is slow. .

The accuracy of the output level of such a continuous signal peak value detection circuit is determined by the number of bits of the counter 10 and the IJA converter 11. Even Uj8 pinto counter and DA
When a converter is used, the peak value can be detected with good linearity at 1/256 of the maximum output level of the DA converter, ie, 3 degrees.

Further, t5 is determined by the response characteristics of the comparator 14, which is the input frequency range for this circuit to operate correctly.

As an example, a signal with a frequency of 301 to 111z is modulated with a modulation depth of 0.
~100%, vibration Φ', J' at modulation frequency 100kHz
, 'J.J.

i! 1. When the input signal is WL, the frequency of the clock signal is 15 MHz, and the number of bits of the counter and 1-) A converter is 8 bits, the 1vI is less than 1%.
An analog output corresponding to the envelope of the peak value of the input signal was obtained at v degrees.

In addition, in the above explanation, continuous intersection p11. Although the wave peak detection circuit has been described as a circuit for use in the magnetic disk inspection device 1'', it can also be used in other magnetic storage inspection devices such as magnetic tape. It can also be used as a general AM decentralizer.

As described above, the continuous alternating current bIf and signal peak value detection circuit according to the present invention can detect the peak value of a continuous alternating current signal with high accuracy and good linearity in a high frequency region.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional continuous AC signal peak value detection circuit, FIGS. 2, 3, and 3 are circuit diagrams showing an example of the rectifier circuit in FIG. 1, and FIG. A block diagram showing an embodiment of the signal peak value detection circuit, FIG. 5 is a waveform diagram showing the operation of the circuit in FIG. 4, and FIGS. 6 and 7 are circuits showing examples of the level comparison circuit in FIG. 4. It is a diagram. 1... Input continuous AC signal, 2... Rectifier circuit, 3... Integrating circuit, 4... Analog output, 5, 6...・Transistor, 7...
...Diode, 8...Calculation increaser 11, 9...
... Level comparison circuit, 10 ... Up/down Φ counter, 11 ... I) A converter, 12
...Clock signal, 14.17...Ratio'I
Q: r, l 5... Monostable multi-pie break-116/integrator circuit.

Claims (1)

[Claims] A DA converter that converts a digital signal into an analog signal, a level comparison circuit that compares the analog signal with the peak value of the input continuous alternating current signal, and control of the addition count and subtraction argument of the clock signal by the output of the level comparison circuit. and an up/down counter for outputting the digital signal, the continuous alternating current signal peak value being configured such that the level of the analog signal is approximately equal to the peak value of the input continuous alternating current signal. detection circuit.