JPH04192610A - Automatic variable clipping circuit - Google Patents

Abstract

PURPOSE:To clip an input signal without adjusting a clipping voltage on each occasion against fluctuation of the input signal by adjusting the clipping voltage automatically in response to a level of the input signal. CONSTITUTION:The clipping circuit is provided with a linear detection circuit 1 half-wave-rectifying an input signal and integrating and outputting the signal subject to half wave rectifying, an amplifier circuit 2 amplifying an integrated signal from the linear detection circuit 1 and outputting the result to a cathode of a Zener diode 11 and an inverting circuit 3 inverting the signal amplified by the amplifier circuit 2 and outputting the result to an anode of the other Zener diode 10. Thus, when the input signal passes through the Zener diodes 10,11, an excess voltage component of the input signal is automatically clipped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic variable clip circuit that automatically adjusts a clip voltage according to the level of an input signal.

[Prior Art] Fig. 3 is a diagram showing a conventional clip circuit. In the figure, (lO) is a Zener diode whose cathode side is connected in parallel to the input signal, and (11) is a Zener diode connected in parallel to the input signal. Connect the anode side of the diode (10) and the ground,
It is a constant voltage power supply that applies a constant reverse bias to the positive signal component of the input signal. (12) is parallel to the input signal,
and a Zener diode (13) connecting the anode side.
) is a constant voltage power supply that connects the cathode side of the Zener diode (12) and ground, and applies a constant reverse bias to the negative signal component of the input signal. (14) is a gain resistor R connected in series with the input signal.

The conventional clip circuit is constructed as described above, and FIG. 4 is an explanatory diagram of the operation of the clip circuit shown in FIG. 3, and its operation will be explained.

When the input signal shown in FIG. 4(a) is input to the input side of the clip circuit, the positive voltage component of the input signal is converted to a constant positive voltage by the Zener diode (10) and the constant voltage power supply (11). At the same time, the voltage component h of the input signal is compensated for up to a certain negative voltage formed by the Zener diode (12) and the constant voltage power supply (13), and the voltage beyond that is clipped. Clip. Then, as shown in FIG. 4(b), the excessively pulsed input signal is output from the clip circuit in a clipped state.

[Problems to be Solved by the Invention] In the conventional clipping circuit as described above, the excessive input signal is clipped and the clipping voltage is kept constant. Therefore, when the input signal level fluctuates, it is necessary to manually There was a problem in that constant voltage power supplies (11) and (13) had to be adjusted.

The present invention has been made to solve such problems, and an object of the present invention is to provide an automatic variable clip circuit that can automatically adjust a clip level according to the level of an input signal.

[Means for Solving the Problems] The automatic variable clip circuit according to the present invention includes one Zener diode whose anode is connected to the input terminal side and the other Zener diode whose cathode is connected to the input terminal side. The circuit that clips the input signal includes a linear detection circuit that half-wave rectifies the input signal, integrates and outputs the half-wave rectified signal, and amplifies the integrated signal from the linear detection circuit. The device includes an amplifier circuit that outputs the amplified signal to the cathode of one Zener diode, and an inverter circuit that inverts the signal amplified by the amplifier circuit and outputs the amplified signal to the anode of the other Zener diode.

[Function] The present invention has one Zener diode whose anode is connected to the input terminal side and a Zener diode whose cathode is connected to the input terminal side, and an input signal input to the input terminal. is half-wave rectified by a linear detection circuit, and the half-wave rectified signal is integrated and output to an amplifier circuit.The amplifier circuit amplifies the integrated signal and outputs it to the cathode of one Zener diode, and also outputs it to the inverting circuit. The inversion circuit inverts the signal amplified by the amplifier circuit and outputs it to the anode of the other Zener diode, so when the input signal passes through the Zener diode, the excessive voltage component of the input signal is automatically removed. You can cri-rep.

[Example] FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In the figure, (1) is a linear detection circuit, which is connected in parallel to the input signal and consists of an operational amplifier, a diode, an integrating circuit, etc., and it half-wave rectifies the input signal a and obtains a time constant from the integrating circuit. Outputs the signal. (1a) is the input resistor, (1b) is the inverting amplifier, (le), (ld
) is the detection diode, (1e) is the voltage dividing resistor, (1f)
is a time constant setting resistor and (1g) is a time constant setting capacitor. '(2) is an amplifier circuit connected in series to the signal from the linear detection circuit (1), consisting of an operational amplifier and a resistor, and connected to the signal from the linear detection circuit (1).
1) Amplify the signal from Zener diode (11)
output to the cathode side of the circuit and an inverting circuit (described later). (2
a) is a normal rotation amplifier, and (2b) and (2c) are gain setting resistors R1 and R2.

(3) is an inverting circuit, which is connected in series with the signal from the amplifier circuit (2) and consists of an operational amplifier and a resistor. output to the side. (3a) is an input resistor, (3b) is an inverting amplifier, and (3C) is a gain resistor.

The automatic variable clipping circuit of the present invention is constructed as described above, and FIG. 2 is a timing chart showing the operation of FIG. 1, and the operation will be explained.

First, the input signal (a) fy' is half-wave rectified (detects the negative component of the input signal) by an inverting amplifier (1b), a detection diode (lc), and a detection diode (1d). and outputs it to an integrating circuit (described later). Then, the half-wave rectified input signal is saturated in the integrating circuit composed of the time constant setting resistor (if) and the time constant setting capacitor (Ig) (time constant capacitor 1g, time constant resistor 1f, and The output signal flows into the inverting amplifier via the detection diode 1d, so the time constant capacitor is charged), and the output signal shown in FIG.
) is output.

The amplifier circuit (2) amplifies the integrated signal with a non-rotating amplifier (2a) according to the ratio (R2/R1 times) of the gain setting resistor R1 (2c) and the gain setting resistor R2 (2b). The negative potential clip voltage (output signal C
) is output to the cathode side of the Zener diode (11) and the inverting circuit (3). The potential across the Zener diode (11) exceeds the Zener potential, and a negative clip voltage corresponding to the input signal a is applied.

On the other hand, the inverting circuit (3) inverts the negative potential output signal C amplified by the amplifier circuit (2) with the inverting amplifier (3b) to create a positive potential clip voltage (output signal d) shown in FIG. 2(d). )
is output to the anode side of the Zener diode (10). A positive clip voltage corresponding to the input signal a is applied to the potential across the Zener diode (10).

In this way, the linear detection circuit (1), the amplifier circuit (2), and the inverting circuit (3) are used to apply a negative clip voltage and a positive clip voltage to the Zener diodes with different directions, respectively, according to the input signal a. By applying a voltage, the excessive voltage component of the input signal a can be automatically clipped and removed as shown in FIG. 2(e).

[Effects of the Invention] As described above, according to the present invention, since the clip voltage can be automatically adjusted according to the level of the input signal,
The input signal can be clipped without adjusting the clip voltage each time the input signal changes.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is a timing chart showing the operation of Fig. 1, Fig. 3 is a diagram showing a conventional clip circuit, and Fig. 4 is an explanatory diagram of the operation of the clip circuit. be. In the figure, (1) is a linear detection circuit, (2) is an amplifier circuit, (3) is an inverting circuit, and (10) and (11) are Zener diodes. Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Muneharu Sasaki (b) (C) (d) (e) Timing chart showing the operation of Figure 1 Figure 2

Claims (1)

[Scope of Claims] In a circuit for clipping an input signal, the circuit includes one Zener diode whose anode is connected to the input terminal side and the other Zener diode whose cathode is connected to the input terminal side, and which clips an input signal. A linear detection circuit that half-wave rectifies an input signal, integrates and outputs the half-wave rectified signal, and an amplifier that amplifies the integrated signal from the linear detection circuit and outputs it to the cathode of one of the Zener diodes. An automatic variable clipping circuit comprising: a circuit; and an inverting circuit that inverts the signal amplified by the amplifier circuit and outputs the inverted signal to the anode of the other Zener diode.