JPH05121962A - Peaking circuit - Google Patents

Abstract

PURPOSE:To improve the degree of freedom of deciding a position of a variable resistor equivalently and to allow the circuit to easily cope with an EVR or the like. CONSTITUTION:A VCA1 is provided to the other terminal of a capacitor 50 and an output signal of the VCA1 is fed back via a resistor R2. Then the gain of the VCA1 is adjusted by a variable resistor 2, resulting in that its input impedance is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peaking circuit suitable for dealing with EVR and the like.

[0002]

2. Description of the Related Art In a damping amount adjusting type LCR peaking circuit, as can be understood from FIG. 4, a signal passes through an adjusting volume R _V. Therefore, in the case of a high frequency, the signal lines L ₁ , L
Extending ₂ causes problems, so it cannot be extended.

[0003]

Therefore, for example, when total adjustment is required in the manufacturing process, the degree of freedom of arrangement of the volume R _V is small even when it is desirable to arrange the volume R _{V at} the end portion of the substrate. I can't actually go up.

It is an object of the present invention to provide a peaking circuit which is equivalently improved in the degree of freedom of volume arrangement and is easily adapted to EVR and the like.

[0005]

A peaking circuit according to the present invention is, for example, as shown in FIG. 1, a damping amount adjusting type peaking circuit, which comprises a feedback voltage control amplifier 1 and a feedback voltage control amplifier. And a control means 2 in which the input impedance is changed by changing the gain of 1.

[0006]

In the peaking circuit according to the present invention, the gain of the feedback voltage control amplifier is changed to change the input impedance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a peaking circuit according to the present invention will be described below with reference to the drawings. In FIG. 1, L
A resistor 20 and a capacitor 50 are provided at one end of the C circuit 10.
And the other end of the resistor 20 is connected to the transistor 30.
Of the transistor 30 and the emitter terminal of the transistor 30 is grounded via the resistor 40.

At the other end of the capacitor 50,
VCA (Voltage Control Amplifier) 1
Is provided, and the output signal of the VCA1 is fed back to its own input terminal side via the resistor R ₂ . Further, the gain of the VCA 1 is adjusted by the variable power source (volume) 2, and thereby the input impedance of the entire circuit is changed.

In this case, when G is the gain of VCA1, (R _V value) = R ₂ / (1−G), and the same characteristics as the conventional example of FIG. 4 can be obtained (see FIG. 2). It suffices to determine R ₂ and the variable gain range and adjust with the volume 2.

In FIG. 2, {R ₁ / (1+
G)} = R _V.

Further, FIG. 3 shows a characteristic curve in this embodiment, and when the volume 2 is adjusted, the gain is changed with the characteristic shown by the broken line or the solid line in FIG. As described above, in this embodiment, V
Since the gain of CA1 is changed by the volume 2, the degree of freedom of arrangement of the volume 2 is improved equivalently to the conventional volume R _V.

Therefore, it is effective when a total adjustment is required in the manufacturing process of the HD-VTR, the RF equalizer, etc., and the EVR etc. can be easily dealt with.

[0013]

As can be understood from the above description, in the peaking circuit according to the present invention, the gain of the feedback voltage control amplifier is changed and the input impedance is changed.

Therefore, the signal line can be extended in terms of mounting, and the degree of freedom in determining the position of the volume is equivalently improved.

Further, it is possible to easily cope with a case where a total adjustment is required such as EVR.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a preferred embodiment of a peaking circuit according to the present invention.

FIG. 2 is an explanatory diagram showing that the circuit of the embodiment is equivalent to the conventional example.

FIG. 3 is an explanatory diagram showing characteristics of VCA.

FIG. 4 is an explanatory diagram of a conventional example.

[Explanation of symbols]

1 VCA 2 Volume R ₂ resistance

Claims (1)

[Claims] 1. A damping amount adjusting type peaking circuit comprising: a feedback voltage control amplifier; and a control means for changing the input impedance by changing the gain of the feedback voltage control amplifier. Peaking circuit characterized by.