WO2001018959A1

WO2001018959A1 - Variable amplitude equalizer

Info

Publication number: WO2001018959A1
Application number: PCT/JP1999/004779
Authority: WO
Inventors: Masayoshi Suzuki
Original assignee: Fujitsu Limited
Priority date: 1999-09-02
Filing date: 1999-09-02
Publication date: 2001-03-15

Abstract

A variable amplitude equalizer exhibiting a variable amplitude-frequency response suitable for high-frequency applications is provided to equalize the amplitude frequency shift of a transmission signal. The equalizer is characterized generally by having a hybrid circuit provided with two distribution ports and an isolation port for an input port and variable impedance means connected with the two distribution ports of the hybrid circuit. The hybrid circuit supplies signals through its isolation ports.

Description

Description Variable amplitude equalizer Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplitude equalizer that equalizes an amplitude frequency deviation of a transmission signal, and more particularly to a variable amplitude equalizer that changes an amplitude frequency characteristic suitable for a high frequency.

Conventionally provided modulation or demodulation integrated circuits have been difficult to operate above the VHF band; however, recent advances in analog IC technology have been remarkable, and in recent years modulation or demodulation that can operate up to the UHF band has been remarkable. _c demodulation integrated circuit is generally provided therefore, possible to perform modulation and demodulation which has been conventionally IF signal band direct RF signals, and the it is necessary to configure wake no peripheral circuits in the RF signal band occurs Have been. One of the peripheral circuits is a variable amplitude equalizer. The variable amplitude equalizer is used as a part of its function to provide an inverse characteristic to the amplitude characteristic of the amplifier and to flatten the amplitude characteristic of the amplifier in a wide band.

Fig. 1 shows a conventional general variable amplitude equalizer. In the figure, it is composed of resistors 1 ぃ 1 ₂ and reactance circuits 2 and 3. The reactance circuit elements 2 and 3 have their reactance circuit elements and their configurations determined according to the desired amplitude frequency characteristics, and capacitors and coils are mainly used as the reactance circuit elements.

In the conventional variable amplitude equalizer, the amplitude frequency characteristics are made variable by changing the circuit element values of the reactance circuits 2 and 3. Here, as means for changing the circuit element value, there are a mechanical method and an electric method.

As a mechanical method, a variable capacitor and a variable coil are used in a part of the reactance circuits 2 and 3. Electrical methods include reactance circuit 2,

The variable capacity diode is used for a part of 3.

Also, as an example of a conventional variable amplitude equalizer, a variable undulation amplitude generator is disclosed in Japanese Patent Publication No. 53-135857. The configuration of this variable undulation amplitude generator is as follows: The main path and the sub path are composed of a hybrid circuit.The main path or the sub path is provided with a variable phase shifter and a delay line, and the signal after passing through the variable phase shifter and the delay line is coupled with the main path and the return path. It equalizes the amplitude characteristics of the signal with:

In such a conventional variable amplitude equalizer, a main path and a return path are branched, and one line is provided with a delay line and a variable phase shifter, and at least four power distribution / combining means are required. Disclosure of the invention

Here, as described with reference to FIG. 1, a variable capacitor or a variable coil, which is a method of mechanically changing a circuit element value, is not suitable for a high frequency. It is only applicable up to the 300 MHz band.

Furthermore, it is difficult to simultaneously change the element values of the variable capacitors and the variable coils of the reactance circuits 2 and 3 without losing the balance. That is, it is difficult to make the capacitance of the capacitor electrically variable by using a variable capacitance element, and it is difficult to make the inductance of the coil electrically variable. Furthermore, in order to change the variable capacitance diode, which is a method of electrically changing the circuit element value, without breaking the balance of the element value relationship between the reactance circuits 2 and 3, it is necessary to balance the applied voltage to the variable capacitance diode. Therefore, a control circuit for controlling the control is required, which is an obstacle to inexpensive and miniaturization.

Also, in the variable undulation amplitude generator disclosed in the above-mentioned Patent Application Publication No. 53-13857, it is necessary to branch into two lines, a main road and a sub road, and a delay is added to one of the lines. An extension line and a variable phase shifter are required, and at least four power distribution and synthesis means are required. Therefore, the circuit configuration is complicated and it is difficult to reduce the size and cost.

Therefore, the object of the present invention is to provide a high-frequency, variable-amplitude variable amplitude element which is suitable for high-frequency operation without losing the balance of the element value relation. To provide a gasifier.

The basic configuration of the variable amplitude equalizer according to the present invention that achieves the above object is as follows: a hybrid circuit having two distribution ports and an isolation port with respect to an input port; Variable impedance means connected to each distribution port, wherein the signal is transmitted from the isolation port of the hybrid circuit. Output a signal.

Preferably, in the variable amplitude equalizer, the impedance variable means is a variable resistor.

Preferably, in the above-mentioned configuration, the impedance variable means includes: a capacitor and a PIN diode connected in series; a capacitor side of the capacitor and the PIN diode connected in series is connected to each distribution port of the hybrid circuit; The coil side is grounded, a coil is connected between the capacitor and the PIN diode, and the other end of the coil is connected to a control signal input terminal.

Further features of the present invention will become apparent from the embodiments of the present invention described with reference to the following drawings. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram for explaining a conventional general variable amplitude equalizer.

FIG. 2 is a diagram illustrating the principle of the present invention.

FIG. 3 is a diagram illustrating an equivalent circuit of the hybrid circuit in FIG. FIG. 4 is a characteristic diagram showing an example of the relationship between frequency and pass loss.

FIG. 5 is a characteristic diagram characteristically showing the characteristics on the left and right sides of the center frequency in the characteristic diagram of FIG.

FIG. 6 is a diagram showing the configuration of the first exemplary embodiment of the present invention.

FIG. 7 is a diagram showing the configuration of the second exemplary embodiment of the present invention.

FIG. 8 is a diagram showing the configuration of the third example of the present invention.

FIG. 9 is a diagram showing simulation results for demonstrating the effects of the present invention.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or similar elements are described with the same reference numerals or reference symbols.

Fig. 2 is a diagram for explaining the principle of the variable amplitude equalizer according to the present invention. In the figure, a hybrid circuit 11 has two distribution ports 1 2 ぃ 1 for an input port 13. _C with 2 ₂ and isolation port 1 4

Variable impedance unit 1 5 "1 5 ₂ is connected to the hybrid preparative circuits 1 each distributable port 1 of 1 2 I 1 2 _2.

The input terminal 13 is connected to the input port 13i of the hybrid circuit 11, and the output terminal 14 is connected to the isolation port 14 of the hybrid circuit 11.

Fig. 3 shows the equivalent circuit represented by the lumped constant circuit of the hybrid circuit 11: The passing characteristic between the input port 13 of the hybrid circuit 11 and the isolation port 14 i is as follows. As shown in FIG. 4, the amplitude frequency characteristic has a concave shape around the set center frequency of the hybrid circuit 11.

When there is no reflection from the distribution boats 1 2, 1 2 _{2, the signal} from the input boat 1 3, from the counterclockwise path to the isolation boat 1 4, and the signal from the clockwise path, the isolation port When the phase difference of the signal reaching 14 i is 180 degrees and it cancels out, the output signal of the isolation port 14 i is almost 0, but there is reflection from the distribution port 1 2 ^ 1 2 ₂ In this case, a signal that has undergone a phase rotation of 270 degrees from the clockwise path is output from the isolation port 14i.

Therefore, the depth of the concave amplitude frequency characteristic depends on the characteristic impedance of the hybrid circuit 11 and the impedance variable means 15 connected to the two distribution ports 1 2 1 2 ₂ of the hybrid circuit 11. 5 ₂ is determined by the relationship between the. The connected impedance variable means 15 and 15 ₂ are equal to the characteristic impedance of the hybrid circuit 11 and become maximum in the non-reflection condition (A in Fig. 4), and conversely in the total reflection condition (Fig. 4). , B).

Therefore, it is possible to set a predetermined amplitude frequency characteristics become the center frequency of the hybrid bets circuit 1 1 As desired, by the this changing the variable impedance unit 1 5 There 1 5 ₂ the amplitude-frequency characteristic variable .

For example, as shown in FIG. 5A, when it is desired to obtain an amplitude frequency characteristic of a downward-sloping primary slope, the center frequency of the split circuit 11 is set to a frequency higher than a predetermined amplitude frequency band. On the other hand, as shown in FIG. 5B, when it is desired to obtain the amplitude frequency characteristic of the first-order slope falling leftward, the intermediate frequency of the hybrid circuit 11 is set to a predetermined amplitude. Set to a lower frequency side than the frequency band - By varying the variable impedance unit 1 5 There 1 5 _2,, respectively Re SOZ 5 A, the amplitude frequency characteristic as shown in FIG. 5 B variable:

Next, an embodiment according to the principle of the variable amplitude equalizer of the present invention will be described. FIG. 6 and FIG. 7 are diagrams showing the configuration of an embodiment of the variable amplitude equalizer of the present invention using a generally provided laminated hybrid. In the figure, those that are the same as those shown in Figure 2 are denoted by the same symbols:

In the embodiment of FIG. 6, as a method of mechanically changing the element values, in the configuration diagram of the case where the in-pin one dance varying means 1 5 There 1 5 ₂ of the variable resistor 2 1 There 2 1 ₂ The variable resistor 2 1 2 1 ₂ is a variable element in which two elements are linked and changes. By changing the variable resistor 2 1 2 1 ₂ , the impedance changes. As described with reference to FIG. 5, the amplitude frequency characteristic varies.

In the embodiment of FIG. 7, a method for electrically changing the element values is a configuration diagram of a case where the impedance varying means 1 5 There 1 5 ₂ PI New diode 2 s 3 2 3 _2. The PIN diode has a characteristic that the high-frequency impedance changes by controlling the current.

In the figure, the same components as those shown in FIG. 2 are indicated by the same symbols, to enter the DC control signal from the control signal input terminal 2 2 for PIN diodes 2 s 3 2 3 _2.

Coil 2 4 I 2 4 ₂ and capacitor 2 5 I 2 5 ₂ influx inhibiting and to the control signal input terminal 2 2 side of the respective high-frequency signals, for inflow inhibiting into Haipuriddo circuit 1 1 DC control signal Be provided.

Accordingly, a control signal is input to the control signal input terminal 2 2, by varying the high frequency resistance component of a PIN diode 2 s 3 2 3 _2, high-frequency impedance connected to the dispensing port 1 2 There 1 2 ₂ changes The amplitude frequency characteristics can be varied.

FIG. 8 is a diagram showing another embodiment according to the present invention. In this embodiment, the hybrid circuit 11 is configured as a branch line type. That is, Figure In the eighth embodiment, the hybrid circuit 11 is configured as a distributed constant circuit. As described above, in the present invention, it is possible to use either a distributed constant circuit or a lumped constant circuit for the hybrid circuit 11.

Figure 9 is a simulation results demonstrating the effect of the present invention, variable amplitude when changing fraud and mitigating risk RF impedance Z of the PIN diode when the current I _D of the PIN diode 23 have 23 ₂ to the configuration of FIG. 7 The figure shows the frequency characteristics of the equalizer.

9, the frequency characteristics A 1, A2, A 3 · '· Α 1 0 corresponding to the PIN Daio over de 23 had 23 _second current I. The high frequency impedance Z _L of the PIN diode at that time is as shown in the following table.

Characteristic curve Z _L (Ω) I _D (mA)

A 1: 50 0 6 5

A2: 70 0 4 7

A3: 90 0 3 8

A4: 1 1 0 0 3

A5: 1 30 0 28

A 6: 1 50 0 23

A 7: 1 70 0 2 1

A 8: 1 90 0 1 9

A 9: 2 1 0 0 1 5

A 1 0: 230 0 1 3 Industrial applicability

As described above with reference to the drawings, according to the present invention, the present invention is suitable for high frequencies and can be varied without breaking the balance of element values, which greatly contributes to cost reduction and miniaturization.

Claims

The scope of the claims

1. For the input boat, a hybrid circuit with two distribution ports and an isolation port,

Variable impedance means connected to each distribution port of the hybrid circuit;

A variable amplitude equalizer characterized by being configured to output a signal from an isolation port of the hybrid circuit.

2. In Claim 1,

The variable impedance equalizer, wherein the impedance variable means is a variable resistor.

3. In claim 1,

The impedance variable means is constituted by a PIN diode,

The PIN diode is connected through a capacitor to a distribution port of the hybrid circuit,

A variable amplitude equalizer characterized in that a control signal of the PIN diode is supplied through a coil to a connection point between the PIN diode and a capacitor.

4. In any one of claims 1 to 3,

The variable amplitude equalizer, wherein the hybrid circuit is formed by a lumped constant circuit.

5. In any one of claims 1 to 3,

The variable amplitude equalizer, wherein the hybrid circuit is configured by a branch line type distributed constant circuit.