JPH1117587A - Continuously variable tilt circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuously variable tilt circuit by changing steplessly a tilt characteristic so as to fine-adjust the correction of a different attenuation. SOLUTION: The continuously variable tilt circuit corrects a pass attenuation different according to a frequency of signal passing through a cable, and is provided with a variable attenuator 5 that attenuates a low frequency component in received signals for a full frequency band, a pass circuit 7 that passes high frequency components in the received full frequency band signals without attenuation and a coupling transformer 9 that couples the attenuated low frequency component from the variable attenuator 5 with the high frequency component not attenuated from the pass circuit, and varies continuously the attenuation of the low frequency component by the variable attenuator 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt (TILT) circuit for correcting a different amount of passage attenuation depending on the frequency of a frequency signal passing through a cable, and more particularly to a tilt circuit that changes the tilt characteristic steplessly. The present invention relates to a continuously variable tilt circuit capable of finely adjusting the amount of attenuation.

[0002]

2. Description of the Related Art In general, a high-frequency signal passing through a cable has a different amount of attenuation depending on its frequency, and becomes larger as the frequency becomes higher. Therefore, when a signal in the entire frequency band from a low frequency to a high frequency is passed through a cable, the signal level is different at the end. That is,
As the frequency of the cable increases as shown in FIG. 3A, the attenuation increases in proportion to the square root of the frequency. It has a so-called Δf characteristic. Therefore, FIG.
There is known a method of connecting a tilt (TILT) circuit having a tilt characteristic (gain) as shown in FIG. 3B in order to correct a different amount of passing attenuation depending on the frequency as shown in FIG.

[0003]

However, in the conventional tilt circuit, the above-mentioned tilt characteristics (gain) are switched in a stepwise manner as shown by C, D and E in FIG. There was a problem that the tilt characteristics could not be finely adjusted, and the optimum tilt characteristics could not be obtained.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem, and an object of the present invention is to provide a continuously variable type which can finely adjust the correction of the above different attenuation by changing the tilt characteristic steplessly. It is to provide a tilt circuit.

[0005]

In order to achieve the above object, the present invention provides a continuously variable tilt circuit for compensating for a different amount of passing attenuation depending on the frequency of a frequency signal passing through a cable. A variable attenuator for attenuating low frequency components of the signal of the above, a pass circuit that passes without attenuating high frequency components of the input signal of the entire frequency band, and a variable attenuator A coupling transformer for coupling the attenuated low frequency component and the non-attenuated high frequency component from the path circuit, wherein the attenuation of the low frequency component by the variable attenuator is continuously variable. It is characterized by being. Another feature of the present invention is that the variable attenuator is capable of continuously changing the attenuation of the low frequency component.
Having second and third variable resistors.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a circuit diagram of a continuously variable tilt circuit embodying the present invention, and FIG. 2 is a graph showing how the tilt characteristic changes continuously in the continuously variable tilt circuit shown in FIG. As shown in FIG. 1, the continuous variable tilt circuit includes a first matching inductor 3 having one end connected to the input terminal 1 and a variable attenuator 5 connected to the other end of the first matching inductor 3.
A pass circuit 7 connected to the other end of the first matching inductor 3; a variable attenuator 5 and a pass circuit 7;
, A high-pass inductance 11 and a first capacitor 13 connected between the variable attenuator 5 and the ground, and an intermediate tap between the variable attenuator 5 and the coupling transformer 9. It has an inductance 15 and a second capacitor 17 connected between 9a and the ground, and a second matching inductor 21 connected between the coupling transformer 9 and the output terminal 19.

The variable attenuator 5 includes first and second variable attenuators.
And third variable resistors 23, 25, 27,
One end of the first variable resistor 23 is connected to the other end of the first matching inductance 3, and the other end of the first variable resistor 23 is connected to the other end of the coupling transformer 9. One end of the second variable resistor 25 is connected to the other end of the first matching inductance 3, and the other end is connected to the high-pass inductance 11 and the first capacitor 13. One end of the third variable resistor 27 is connected to the other end of the first variable resistor, and the other end is connected to the inductance 15, the second capacitor 17, and the intermediate tap 9 a of the coupling transformer 9.
It is connected to the. Further, the pass circuit 7 includes a pass capacitor 29 and a pass interactor 31 connected in series.
One end of the pass capacitor 29 is connected to the other end of the first matching inductor 3, the other end of the pass capacitor 29 is connected to one end of the pass inductor 31, The other end is connected to one end of the coupling transformer 9 and one end of the second matching inductor 21.

Next, the operation of the continuously variable tilt circuit having the above configuration will be described. First, the variable attenuator 5 can change the amount of attenuation by changing the resistance values of the first, second, and third variable resistors 23, 25, and 27. Here, when the attenuation of the variable attenuator 5 is set to 0, the signal of the entire frequency band input from the input terminal 1 via the first matching inductor 3 is not changed to the output terminal 19. 2 and the tilt characteristic (constant gain) as shown by F in FIG. Next, the first to third variable resistors 23-2
When the attenuation of the variable attenuator 5 is increased to an arbitrary value by changing the resistance value of the variable attenuator 7, the low frequency component of the signal of the entire frequency band input from the input terminal 1 is reduced by the variable attenuator. 5, the signal is attenuated by passing through the high-pass inductance 11, and a high frequency component of the signal in the entire frequency band is not attenuated by passing through the pass circuit 7. The attenuated low frequency component and the unattenuated high frequency component are smoothly coupled by the coupling transformer 9 and output from the output terminal 19 via the second matching inductor 21. Therefore, the tilt characteristics (tilt value) of the tilt circuit
Is, for example, as shown in FIG. As described above, in this continuous variable tilt circuit, the attenuation of the variable attenuator 5 is continuously changed by continuously changing the resistance values of the first to third variable resistors 23 to 27. Thus, for example, the tilt characteristic of the tilt circuit can be continuously changed from F to G as indicated by the arrow in FIG. Therefore, the correction of the attenuation can be finely adjusted. In the above embodiment, the first and second matching inductors are inserted in order to match the input and output impedances.

[0009]

As described above, according to the present invention, since the tilt characteristic (tilt value) can be continuously changed, the correction of the different attenuation amounts can be finely performed by changing the tilt characteristic steplessly. Can be adjusted.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a continuously variable tilt circuit embodying the present invention.

FIG. 2 is a graph showing how the tilt characteristic changes continuously in the continuously variable tilt circuit shown in FIG. 1;

FIG. 3 is a graph showing attenuation of a frequency signal passing through a cable and tilt characteristics of a tilt circuit.

FIG. 4 is a graph showing tilt characteristics of a conventional tilt circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input terminal, 3, 21 ... Matching inductor, 5 ...
Variable attenuator, 7 ... pass circuit,
9: coupling transformer, 9a: middle tap, 11: high-pass inductance, 1
3, 17 ... capacitor, 15 ... inductance,
19: output terminal, 23, 25, 27: variable resistor, 29: pass capacitor, 31: pass inductor,

Claims (2)

[Claims] 1. A continuously variable tilt circuit for correcting a passing attenuation amount that varies depending on the frequency of a frequency signal passing through a cable, wherein the tilt circuit is for attenuating a low frequency component of a signal in an entire frequency band that is input. A variable attenuator, a pass circuit through which the high frequency component of the input signal of the entire frequency band is passed without attenuating, a low frequency component attenuated by the variable attenuator, and attenuation by the pass circuit A continuously variable tilt circuit, comprising: a coupling transformer for coupling a high frequency component that is not to be processed; and wherein the attenuation of the low frequency component by the variable attenuator is continuously variable. 2. The variable attenuator according to claim 1, wherein the variable attenuator has first, second, and third variable resistors for continuously changing the amount of attenuation of the low frequency component. Continuously variable tilt circuit.