JPH025420Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a circuit that detects the peak value of a small and steep voltage waveform of a duty factor, such as a spike voltage of a switching power supply.

A conventional circuit of this type consists of one impedance converter, one diode, and one impedance converter, as shown in Figure 1.
It consists of several capacitors. Therefore, it has been impossible to detect the peak value of a small and steep voltage waveform of a duty factor, such as a spike in a switching power supply as shown in FIG. In other words, when the value of the capacitor is increased, as shown in C _L in Figure 3, the spike waveform is so short that it is not possible to charge the capacitor until the peak value is equal to the output voltage of the capacitor, resulting in a voltage that is much lower than the peak value. Only values can be output. Also, if C is chosen to be small like C _S in Figure 4, the value of the capacitor will follow up to the peak value, but since the capacitance of the capacitor is small, the reverse leakage current of the diode, the internal resistance of the capacitor, and the DC current connected to the output terminal will increase. The peak value voltage could only be maintained for a short time due to the input resistance of the pressure gauge, and as a result, it was impossible to use it as a peak value detection circuit.

The purpose of the present invention is to detect the peak value of a small and steep voltage waveform of a duty factor.

The present invention consists of an input terminal, multiple impedance converters, the same number of delay circuits with slightly different delay times, the same number of diodes, one capacitor, and an output terminal. The input terminals of each impedance converter are connected to each other, the output terminal of each impedance converter is connected to the input terminal of each delay circuit, the output terminal of each delay circuit is connected to one electrode of each diode, and the other electrode of each diode is connected to the output terminal of each impedance converter. This is a peak value detection circuit characterized by connecting the two to each other and to the capacitor and output terminal.

An embodiment of the present invention is shown in FIG. 5, and the case of detecting a positive peak value will be described. The small spike waveform of the duty factor input to the input terminal 6 is input to n impedance converters Z ₁ , Z _{2 .} . . Z _o whose inputs are connected to each other. Then, by passing through connected delay circuits T ₁ , T ₂ , . . . , T _o having slightly different delay times, the spike waveform is delayed in time as shown in a, b, and c in FIG. 6. The diodes D ₁ , D ₂ , ...D _o connected to the rear of these waveforms pass only the positive components, so if the cathodes of each diode are connected to each other, the output terminal 8 will have the waveform shown in Figure 6 d. An improved waveform of the duty factor is obtained in which the shape of the steep waveform is the same, but the number of waveforms existing within the same time is increased. By connecting the capacitor 7 to the output terminal 8, the peak value of this waveform d is detected for each waveform, and the desired peak value voltage can be obtained as in the waveform e.

Here, the waveform e corresponds to the capacitor 7 in FIG.
This is when the value of is set large and the discharge time is lengthened as shown in Figure 3 C _L. As shown in waveform e, the capacitor starts discharging when the first spike waveform ends, but unlike the conventional case, the delayed spike waveform b...c according to the present invention is applied to the capacitor before it is completely discharged, so it is difficult to start charging. The voltage increases sequentially as the spike waveform repeats, and finally becomes equal to the peak voltage.

In this way, by creating multiple new waveforms that are exactly the same as the input signal waveform in time series, it is possible to detect the peak value of the steep voltage waveform of the duty factor with a large high frequency component, which was previously impossible. This makes it possible to measure peak values such as spikes in switching power supplies. In addition, by using the present invention, it is possible to store the peak value as it is at a correct value for a longer period of time than before, so by synchronizing measurements using a high-speed DC voltmeter, it is possible to detect single phenomena with steep waveforms. Peak value measurement is also possible.

Furthermore, by reversing the direction of the diode, it is possible to detect a negative peak value, and by using both in combination, it is also possible to measure a peak value between positive and negative.

[Brief explanation of the drawing]

Figure 1 shows a conventional peak value detection circuit. Figure 2 is an example of a small and steep spike voltage waveform of a duty factor. Figure 3 shows the output waveform when the capacitor value is increased in the circuit shown in Figure 1. Figure 4 shows the output waveform when the capacitor value is also reduced. FIG. 5 shows an embodiment of the positive peak voltage detection circuit according to the present invention. FIG. 6 shows voltage waveforms at various parts in the embodiment of the present invention. In the circuit diagram, 1 and 6 are input terminals, 2, Z ₁ , Z ₂
...Z _o is an impedance converter, 3, D ₁ , D ₂ ,
...D _o is a diode, 4 and 7 are capacitors, 5,
8 is the output terminal, T ₁ , T ₂ , ... T _o are delay circuits with slightly different delay times, and in the waveform diagram, a is a spike waveform, and C _L and C _S are the values when the capacitor value is large and small, respectively. The output waveform at the time, b and c are the spike waveforms when passed through the delay circuit. d is the output waveform assuming no capacitor, and e is the peak value output at the output terminal.

Claims (1)

[Scope of utility model registration request] It consists of an input terminal, multiple impedance converters, the same number of delay circuits with slightly different delay times, the same number of diodes, one capacitor, and an output terminal. Connect each other, connect the output terminal of each impedance converter and the input terminal of each delay circuit, connect the output terminal of each delay circuit to one electrode of each diode, and connect the other electrode of each diode to each other. A peak value detection circuit characterized by being connected to a capacitor and an output terminal.