JPH0730368A - Variable amplitude equalizer circuit - Google Patents

Abstract

PURPOSE:To obtain desired amplitude frequency characteristics by easy adjustment. CONSTITUTION:An input signal IN is bisected by a power distributor 1 and inputted to a variable attenuator 2 and a variable attenuator 3 respectively. The attenuation quantity of the attenuator 2 and the attenuation of the attenuator 3 are controlled externally so that the increment of the attenuator 2 and the decrement of the attenuator 3 vary at the same rate. The signals which are adjusted by the variable attenuators 2 and 3 to optional levels are inputted to an amplitude equalizer 4 and an amplitude equalizer 5. The equalizer 4 has frequency characteristics with a plus linear gradient and the equalizer 5 have frequency characteristics with a minus linear gradient. The output of the equalizer 4 has its phase controlled by a phase shifter 6 externally to eliminate the phase difference between two signal paths. While the two signals are put in phase with each other, they are put together by an electric power synthesizing unit 8, so the level of the output signal OUT can be held constant at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable amplitude equalizer circuit, and more particularly to a variable amplitude equalizer circuit for correcting the first-order inclining amplitude frequency characteristic of a signal of a communication device generated due to long-distance transmission or characteristics of constituent devices. Regarding

[0002]

2. Description of the Related Art In a conventional amplitude equalizing circuit, the amplitude frequency characteristic is changed to an arbitrary value by directly changing the circuit constant of a resonance circuit or a filtering circuit having the amplitude frequency characteristic.

That is, in the conventional amplitude equalization circuit, when the amplitude frequency characteristic is changed, the circuit constant is changed.

[0004]

In the above-mentioned conventional amplitude equalization circuit, in order to change the circuit constant, if it is a lumped constant circuit, it is necessary to replace or adjust each component, and the distributed constant is required. In the case of a circuit, it was necessary to adjust the microstrip line and the stub of the waveguide. This adjustment work is difficult and time-consuming, and due to the change of the circuit constant, not only the frequency characteristics of the amplitude,
There is a drawback that the absolute value often changes.

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide an amplitude equalization circuit capable of obtaining a desired amplitude frequency characteristic by simple adjustment.

[0006]

SUMMARY OF THE INVENTION An amplitude equalization circuit according to the present invention includes a distribution means for distributing an input signal into first and second signal paths, and a signal of the first signal path according to an external command. Attenuator for changing the increase amount of the attenuation amount and the decrease amount of the attenuation amount of the signal of the second signal path at the same ratio, and a first amplitude provided in the first signal path and having a predetermined inclination characteristic. An equalizer; a second amplitude equalizer provided in the second signal path and having a slope characteristic opposite to that of the first amplitude equalizer; and the first and second amplitude equalizers. And a synthesizing means for synthesizing the signals of the first and second signal paths after the amplitude correction.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of an amplitude equalization circuit according to the present invention.

In the figure, an amplitude equalizing circuit according to an embodiment of the present invention is provided in a power divider (DIV) 1 for dividing an input signal IN into two signal paths, and in the two divided signal paths. For the variable attenuators 2 and 3 for adjusting the signal to an arbitrary level, the amplitude equalizers (EQL) 4 and 5 that receive the signal after the level adjustment, and the output of the amplitude equalizer 4. It includes a phase shifter (θ) 6 for phase correction, and a power combiner (COMB) 8 that combines the signals of the two signal paths and outputs an output signal OUT.

In such a configuration, the input signal IN is branched into two by the power distributor 1 and input to the variable attenuator 2 and the variable attenuator 3, respectively. It is externally controlled so as to change the increase amount of the attenuation amount of the variable attenuator 2 and the decrease amount of the attenuation amount of the variable attenuator 3 at the same ratio. The control method may be manual control or feedback control according to the output signal OUT. The signals adjusted to arbitrary levels by the variable attenuator 2 and the variable attenuator 3 are then respectively sent to the amplitude equalizer 4
And the amplitude equalizer 5 are input.

The amplitude equalizer 4 is an amplitude equalizer having a frequency characteristic of positive first-order slope, and the amplitude equalizer 5 is an amplitude equalizer having a frequency characteristic of negative first-order slope, both of which are fixed. Has a specified frequency characteristic. Here, the frequency characteristic of the positive first-order slope refers to a characteristic that rises to the right when the frequency is taken on the horizontal axis and the amplitude is taken to be the vertical axis, and the frequency characteristic of the negative first-order slope is taken to be a characteristic that goes down to the right. Say.

In short, the variable attenuators 2 and 3 adjust the processing ratio between the amplitude equalization processing based on the frequency characteristic of the positive primary slope and the amplitude equalization processing based on the frequency characteristic of the negative primary slope.

Further, the output of the amplitude equalizer 4 is externally phase controlled by the phase shifter 6. This makes it possible to eliminate the phase difference between the two signal paths. In general, when amplitude equalization processing is performed, the phase shifts, and therefore it is not possible to combine the phases as they are. On the other hand, in this example, since the phase shifter 6 is provided in the signal path, it is possible to eliminate the phase difference and combine the two signals while synchronizing the phases. That is, since the power is combined after the phase adjustment, the level of the signal output from the power combiner 8 can always be kept constant.

For example, when it is desired to have a positive first-order slope frequency by the input signal, the attenuation amount of the variable attenuator 2 is decreased, the attenuation amount of the variable attenuator 3 is increased at the same time, and the phase shifter 6 is provided between the two paths. By eliminating the phase difference of 1), it is possible to obtain an output from the power combiner 8 which has a more positive first-order slope and whose signal level does not change.

Similarly, as another embodiment, as shown in FIG. 2, a phase shifter 7 is added to the output side of the amplitude equalizer 5 and a phase shifter is provided in both of the two signal paths. Even with the configuration, it is clear that the same effect can be obtained.

The phase shifters 6 and 7 may be manually controlled or feedback controlled.

In this embodiment, the variable attenuator is provided before the amplitude equalizer, but the variable attenuator may be provided somewhere in the signal path and is not limited to that location. Not something.

Further, although the input signal is branched into two in this example, it is not limited thereto, and may be branched into three or more if necessary.

[0019]

As described above, according to the present invention, the frequency characteristic of the equalizer, which is difficult to adjust, is fixed while changing the amplitude frequency characteristic, and a more general variable attenuator and phaser are used. Since it is configured to be adjusted by using the amplitude equalizer, compared with the conventional amplitude equalizer, there is an effect that the amplitude frequency characteristic can be arbitrarily changed more continuously and without changing the output level.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an amplitude equalization circuit according to the present invention.

FIG. 2 is a block diagram showing the configuration of another embodiment of the amplitude equalization circuit according to the present invention.

[Explanation of symbols]

 1 power distributor 2, 3 variable attenuator 4, 5 amplitude equalizer 6, 7 phaser 8 power combiner

Claims (2)

[Claims] 1. A distribution means for distributing an input signal to first and second signal paths, and an increase amount of signal attenuation of the first signal path and a second signal path of the second signal path in response to an external command. Attenuating means for changing the reduction amount of the signal by the same ratio, a first amplitude equalizer provided in the first signal path and having a predetermined inclination characteristic, and provided in the second signal path. A second amplitude equalizer having a slope characteristic opposite to that of the first amplitude equalizer; and the first and second signal paths after amplitude correction by the first and second amplitude equalizers. Variable amplitude equalization circuit having a combining means for combining the signals of FIG. 2. The synthesizing means synthesizes the phase shifters for adjusting the phases of the signals of the first and second signal paths, and the synthesizer for synthesizing the phase adjusted signals of the first and second signal paths. The variable amplitude equalization circuit according to claim 1, further comprising: