JPH0270105A - Digital rectifier circuit - Google Patents

Abstract

PURPOSE:To rectify an input signal with small amplitude without distortion by alternately closing first and second switches under the control of a polarity discrimination circuit in accordance with the negative or positive of the input signal. CONSTITUTION:In an electronic switch circuit, the non-inversion path of the input signal including the first switch 9 is connected in parallel with the non- inversion path of an input, which includes a polarity inversion circuit 8 and the second switch 10. While the input signal is a positive half-wave, the switch 9 in the non-inversion path is closed and the switch 10 is opened by the output of the polarity discrimination circuit 3. While the input is a negative half-wave, the switch 10 in the non-inversion path is closed, the signal is polarity-inverted in the polarity inversion circuit 8 and the switch 9 is opened by the output of the circuit 3. Since a comparator with small offset is used in the circuit 3, even the input of small amplitude can be rectified without distortion.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an alternating current signal rectifier circuit.

[Prior Art] A bridge rectifier circuit shown in FIG. 3 is a rectifier circuit that has been commonly used in the past.

As is well known, this bridge rectifier circuit consists of four rectifier diodes DI, D2 . D3. D4 are connected in a bridge configuration, and full-wave rectification is performed using the rectification characteristics of diodes.

[Problems to be Solved by the Invention] However, since the bridge rectifier circuit performs rectification by utilizing the forward and reverse characteristics of the diode, the input signal is at a diode-specific operating voltage (typically 0.6 V in the forward direction). ) In the case of a voltage signal with a small amplitude below, the diode does not respond, so it cannot be rectified.
In the case of a signal with a relatively small amplitude voltage of about 2.5 cm, there is a problem in that the rectified waveform is distorted because the forward characteristics of the diode are not linear.

The purpose of the present invention is to solve the problems of the prior art described above,
It is an object of the present invention to provide a digital rectifier circuit which is capable of rectifying a small amplitude voltage signal that is lower than the operating voltage of a diode and is capable of rectifying a relatively small amplitude voltage signal of about 1 to 2 V with small distortion.

[Means for Solving the Problems] The digital rectifier circuit of the present invention connects in parallel a non-inverting path for an input signal including a first on-off switch and a non-inverting path for an input signal including a second on-off switch. According to the determination result of the input signal polarity determination circuit, the first opening/closing switch'
The switch is configured to alternately open and close the switch and the second open/close switch.

[Function] Depending on whether the input signal is positive or negative, the first and second open/close switches 9 are alternately closed under the control of the polarity discrimination circuit. Therefore, the half-wave of one polarity of the input signal is output as is, and the half-wave of the other polarity is inverted and output. That is, the input signal is rectified only through the on/off switch without undergoing nonlinear characteristics such as a diode. As a result, even small amplitude input signals can be rectified without distortion.

[Example] An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the basic configuration of the digital rectifier circuit of the present invention. An AC input signal 1 applied to an input terminal 5 is rectified through an electronic switch circuit 4, and output as a rectified output signal 2 from an output terminal 6. Ru.

Reference numeral 3 denotes a polarity discrimination circuit which discriminates the polarity of the input signal 1 and opens and closes the electronic switch circuit 4 according to the result of the discrimination, that is, the polarity of the input signal 1 which changes instantaneously.

FIG. 2 shows a specific configuration of the digital rectifier circuit. The electronic switch circuit 4 connects in parallel a non-inverting path for the input signal including the first on-off switch 9 and a non-inverting path for the input signal including the polarity inversion circuit 8 and the second on-off switch 10. Become. The polarity discrimination circuit 3 here is composed of a comparator with a small offset, and identifies whether the polarity of the input signal 1 is positive or negative. Time is open/close switch 10
A signal is given to the electronic switch circuit 4 to "close" the circuit. By controlling the polarity discrimination circuit 3, an output obtained by rectifying the input signal is obtained from the output terminal 6 of the electronic switch circuit 4.

That is, during the positive half-wave of the input signal 1, the open/close switch 9 in the non-inverting path is closed by the output of the polarity discrimination circuit 3.
The other open/close switch 10 is "open", and therefore, the positive half wave of the input signal is output from the output terminal 6 as is. Furthermore, during the negative half-wave of the input signal 1, the output of the polarity determining circuit 3 closes the open/close switch 10 on the non-inverting path, and the other open/close switch 9 is "open". Therefore,
From the output terminal 6, the negative half wave of the input signal is inverted and output. In this way, the open/close switches 9 and 10 alternately turn r! # By being closed, an output signal 2 having a waveform as suggested in FIG.
taken from.

Since the polarity discrimination circuit 3 uses a comparator with a small offset, even if the input signal has a small amplitude,
Normally, the offset of a high-precision comparator that can perform the above rectification is 1 nV or less, so this rectifier circuit can rectify even a small amplitude signal of several millivolts without distortion. In addition, as indicated by the dotted line in Figure 2, by placing the amplifier circuit 7 in front of the polarity discrimination circuit 3, the accuracy of polarity discrimination can be extremely easily increased, so even signals with smaller amplitudes can be rectified. It becomes possible to do so.

Furthermore, as is clear from the above description, this rectifier circuit essentially has a characteristic of having a very wide dynamic range. From these points, the present rectifier circuit has an extremely wide range of uses.

Let me show you an example of its use. For example, in detecting an overhead ground wire current in an ultra-high voltage power transmission line, the dynamic range of the fault current may require three digits, which is wider than the normal two digits. For such applications, in the case of a rectifier circuit using conventional diodes, its dynamic
Watercress is not suitable because the limit is 2 digits, but even for ultra-high voltage transmission lines with a wide dynamic range where the fault current reaches 3 digits, it is essential to rectify the overhead ground wire current in the detection device. If a rectifier circuit is applied, accuracy will be improved, and a dynamic range of about four digits can be achieved, making it possible to construct an extremely suitable detection device.

[Effects of the Invention] As described above, according to the rectifier circuit of the present invention, it is possible to rectify input signals with small amplitudes, which is impossible with conventional rectification techniques using diodes.

[Brief explanation of the drawing]

FIG. 1 is a basic diagram of a rectifier circuit showing an embodiment of the present invention, FIG. 2 is a specific circuit diagram thereof, and FIG. 3 is a diagram showing a conventional bridge rectifier circuit. In the figure, 1 is an input signal, 2 is an output signal, 3 is a polarity discrimination circuit, 4 is an electronic switch circuit, 5 is an input terminal, 6 is an output terminal, 8 is a polarity inversion circuit, and 9 is an opening/closing switch that closes when the polarity is positive. , 10 indicate opening/closing switches that close when the polarity is negative.

Claims (1)

[Claims] 1. A non-inverting path for the input signal including the first open/close switch and a non-inverting path for the input signal including the second switch are connected in parallel, and the polarity of the input signal is determined by the input signal polarity determining circuit. A digital rectifier circuit characterized in that an on-off switch and a second on-off switch are alternately opened and closed.