JPH06104676A - Variable resistance attenuator - Google Patents

Abstract

PURPOSE:To obtain the resistance attenuator whose attenuation is made variable in which three resistors being components of a pi or T-shaped resistance attenuator are formed respectively with plural resistors and a prescribed resistor is short-circuited in response to the attenuation among the division resistors. CONSTITUTION:Two resistors 5, 6 are provided between an input terminal 1 and an output terminal 2, a series circuit of resistors 7, 8 is loaded between a connecting point of the two resistors 6 and ground. For example, then an attenuator whose attenuation quantity T2 for a microwave propagated from the input terminal 1 to the output terminal 2 is obtained by short-circuiting the resistors 5, 8. Furthermore, the attenuator whose attenuation is T1 is obtained by short-circuiting the resistors 6, 7 conversely. Furthermore, the attenuator whose attenuation is T1.T2 is obtained when any of the resistors 5-8 is not short-circuited. Thus, the variable resistance attenuator whose attenuation is variable from T1 to T1.T2 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable resistance attenuator for varying a microwave band signal.

[0002]

2. Description of the Related Art In a microwave band amplifier or the like, the characteristics of the amplifier vary greatly due to variations in semiconductor characteristics. In order to avoid this, in a microwave band amplifier, a resistance attenuator having a simple structure is often used for gain adjustment. Figure 8
Is, for example, MICROWAVE JOURNAL 198
9 STATE OF THE ART REFEREN
CE, pp. It is a block diagram of the T-type resistance attenuator shown by 104. In the figure, 1 is an input terminal, 2 is an output terminal, 3
And 4 are resistors. This T-type resistance attenuator is provided with two resistors 3 in series between an input terminal 1 and an output terminal 2, and
The resistor 4 is provided between the connection point of the two resistors 3 and the ground.

Next, the operation will be described. In this type of attenuator, the amount of microwaves propagated from the input terminal 1 to the output terminal 2 can be set by appropriately selecting the values of the resistors 3 and 4. For example, if the attenuation amount is K, the power source impedance connected to the input terminal 1 and the load impedance connected to the output terminal 2 are Z _0, and the values of the resistors 3 and 4 are R ₁ and R ₂ , respectively, R ₁ , R ₂ are respectively given by the following equations.

[0004]

[Equation 1]

[0005]

[Equation 2]

By selecting the resistors 3 and 4 in this way, a fixed-type attenuator having a desired attenuation can be obtained. Further, the impedance when the attenuator side is viewed from the input terminal 1 or the output terminal 2 is always Z ₀ , and VSWR
Is good, and since it is composed of only the resistors 3 and 4, it is possible to obtain flat attenuation characteristics over a wide band with a compact structure. In order to use such a T-type resistance attenuator for adjusting the gain of the amplifier, a plurality of attenuators having different attenuations are prepared, and the attenuator is selected according to the gain of the amplifier. Can be obtained.

[0007]

Since the conventional T-type resistance attenuator is a fixed type, it is necessary to properly use the attenuator according to the characteristic variation of the semiconductor used for the amplifier in order to use it for adjusting the gain of the amplifier. Therefore, it is necessary to prepare a plurality of attenuators having different attenuation amounts and select the attenuator, which causes a problem that the manufacturing time and the manufacturing cost of the amplifier increase.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a resistance attenuator capable of varying the amount of attenuation. By using this attenuator, the amplifier manufacturing time can be increased. , The purpose is to significantly reduce the production cost.

[0009]

The variable resistance attenuator of the present invention divides each of the three resistors constituting the π-type or T-type resistance attenuator into a plurality of resistors, and attenuates the divided resistors. It is configured such that a predetermined resistance is short-circuited according to the amount.

Further, in the variable resistance attenuator of the present invention, at least two π-type or T-type resistance attenuators are connected in series, and at least one resistance is provided between these resistance attenuators, depending on the attenuation amount. The resistance is short-circuited.

Further, in the variable resistance attenuator of the present invention, a plurality of resistance attenuators each having one resistor connected in series are connected in series at both ends of the transmission line having a length of about 1/4 wavelength. At the same time, the predetermined resistance of the resistance attenuator is configured to be short-circuited according to the amount of attenuation.

Furthermore, the variable resistance attenuator according to the present invention has a plurality of resistors connected in series at both ends of a transmission line having a length of about 1/4 wavelength, and among the plurality of resistors described above. The predetermined resistance is short-circuited according to the amount of attenuation.

[0013]

The variable resistance attenuator of the present invention is a π type or T type.
By dividing each of the three resistors forming the resistance attenuator into a plurality of resistors and short-circuiting at least three of the predetermined resistors thus divided, the amount of attenuation can be varied over a wide band with a compact structure.

In the variable resistance attenuator of the present invention, at least two π-type or T-type resistance attenuators are connected in cascade, and at least one resistance is provided between the resistance attenuators, and the resistances are short-circuited. By doing so, the amount of attenuation can be easily changed.

Further, in the variable resistance attenuator of the present invention, a plurality of resistance attenuators each having one resistance connected in series are connected in series at both ends of the transmission line having a length of about 1/4 wavelength. At the same time, by short-circuiting the resistors connected to both ends of a predetermined resistance attenuator, the amount of attenuation can be changed with a simple configuration.

Furthermore, in the variable resistance attenuator of the present invention, a plurality of resistors are connected in series at both ends of a transmission line having a length of about ¼ wavelength, and among the plurality of resistors, By short-circuiting the predetermined resistor, the amount of attenuation can be easily changed with a relatively small structure.

[0017]

【Example】

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. Figure 1
In, 5 to 8 are resistors. This variable resistance attenuator is provided with two resistors 5 and 6 between an input terminal 1 and an output terminal 2, respectively, and a series connection of resistors 7 and 8 between a connection point of the two resistors 6 and ground. The circuit is loaded. Therefore, this variable resistance attenuator can be regarded as having a configuration in which the resistance 3 of the conventional T-type resistance attenuator shown in FIG. 8 is divided into resistances 5 and 6, and the resistance 4 is divided into resistances 7 and 8, respectively. it can.

[0018] Here, the resistance value R _a1 of the resistor 5, the resistance value R _b1 is a number each first resistor 8, as the attenuation T ₁ than the number 2 is obtained, also, the resistance value R _a2 of the resistor 6, the resistor 7 Resistance value R
_b2 is selected such that each attenuation T ₂ is obtained.

Therefore, for example, by short-circuiting both ends of the resistor 5 and the resistor 8 as shown in the figure, it is possible to obtain an attenuator having the attenuation amount T ₂ of the microwave propagated from the input terminal 1 to the output terminal 2. On the contrary, by short-circuiting both ends of the resistor 6 and the resistor 7, an attenuator having the attenuation amount T ₁ can be obtained. Further, when the resistors 5, 6, 7 and 8 are not short-circuited, the attenuation amount T ₁ is not reduced. An attenuator of ₁ · T ₂ can be obtained. In this way, by dividing each of the three resistors constituting the T-type resistance attenuator into two and short-circuiting the three resistors among the divided resistors 5, 6, 7, and 8, It is possible to obtain a variable resistance attenuator capable of varying the attenuation amounts T _{1 to} T ₁ · T ₂ . The variable resistance attenuator of the present invention includes resistors 5, 6, 7,
Since it can be configured with only eight, it is possible to obtain a low VSWR and flat attenuation characteristics over a wide band with a compact configuration.

As described above, by using the variable resistance attenuator of the present invention for adjusting the gain of the amplifier, the amount of attenuation can be set according to the characteristic variation of the semiconductor, so that only one type of attenuator is used. The gain can be adjusted, and the production time and production cost of the amplifier can be significantly reduced.

Embodiment 2 FIGS. 2A and 2B show an example of a structure in which the variable resistance attenuator of the present invention shown in FIG. 1 is constructed by using a microwave integrated circuit. In FIG. 2A, 9 is a dielectric substrate, 10 is a metal island, 11 is a ground conductor, and 12 is a thin metal wire. Metal islands 10 are provided at the connection portions of the resistors 5 and 6, the resistors 7 and 8, and the resistors 6 and 7, respectively, and one end of the resistor 8 is grounded by a ground conductor 11. The metal island 10, the ground conductor 11, and the resistors 5, 6, 7, and 8 are integrally formed on the dielectric substrate 9 by a microwave integrated circuit. Where attenuation T ₂
In order to short-circuit the resistors 5 and 8 in order to obtain, the input terminal 1 and the metal island 10, the metal island 10 and the output terminal 2, and the metal island 10 and the ground conductor 11 are connected with a thin metal wire 12 as shown in the figure. It can be easily realized only by Further, the metal island 10 is not limited to the rectangular shape, and the same applies when an L-shaped metal island 10 is used as shown in FIG. The lengths of the metal island 10, the ground conductor 11, and the metal thin wire 12 are selected to be sufficiently smaller than the wavelength.

Embodiment 3 In the above description, the case where each of the three resistors constituting the T-type resistance attenuator is divided into two has been described. FIG. 3 is a configuration diagram of the variable resistance attenuator of the present invention in which each of the three resistors forming the π-type resistance attenuator is divided into two. This attenuator loads a series circuit of resistors 5 and 6 between an input terminal 1 and an output terminal 2, and a series circuit of resistors 7 and 8 between one end of the resistor 5 and ground and between one end of the resistor 6 and ground. It is of a configuration loaded with. The attenuation amount of this attenuator is the same as that of the variable resistance attenuator shown in FIG.
6, 7 and 8 and, for example, as shown in FIG.
The amount of attenuation can be changed by short-circuiting both ends of and 8.
Since this variable resistance attenuator can also be composed of resistors 5, 6, 7, and 8, it is possible to obtain a low VSWR and a flat attenuation characteristic over a wide band with a compact structure, and it can be easily realized by a microwave integrated circuit.

As described above, each of the three resistors forming the π-type or T-type resistance attenuator according to the present invention is divided into two, and the divided predetermined resistors are short-circuited according to the amount of attenuation. By doing so, a variable resistance attenuator can be realized.
Therefore, by using the variable resistance attenuator of the present invention for the amplifier, the amount of attenuation can be set according to the variation of the semiconductor, so that the gain can be adjusted with only one type of attenuator. Therefore, the manufacturing time and manufacturing cost of the amplifier can be significantly reduced. In the above embodiment, the case where each of the three resistors forming the π-type or T-type resistance attenuator is divided into two resistors has been described, but it may be divided into two or more resistors. . In this case, the gain of the amplifier can be adjusted more accurately. Further, the variable resistance attenuator of these inventions can be constructed only by resistors and has a flat attenuation characteristic over a wide band, so that it is particularly effective for gain adjustment of a wide band amplifier.

Embodiment 4 FIG. 4 is a block diagram of a variable resistance attenuator which is another embodiment of the present invention. In this figure, 13 is the T-type resistance attenuator shown in FIG. 8, and 14 and 15 are resistors.
This variable resistance attenuator is between input terminal 1 and output terminal 2,
Two T-type resistance attenuators 13 connected in cascade are provided, and resistors 14 and 15 are provided between the two T-type resistance attenuators 13.
Of the serial circuit. In general, when a resistor R is loaded in series with a load having an impedance Z ₀ , the microwave attenuation amount K by the resistor R is given by the following equation.

[0025]

[Equation 3]

As is clear from this equation, the resistance R
The attenuation amount K is determined. Therefore, by changing the values of the resistors 14 and 15 loaded between the two T-type resistance attenuators 13 as shown in FIG. 4, the attenuation amount of the microwave propagated to the input terminal 1 to the output terminal 2 is changed. be able to. Here, to change the values of the resistors 14 and 15 loaded between the two T-type resistance attenuators 13, short-circuit both ends of the resistor 15 as shown in the figure, or short-circuit both ends of the resistor 14. It's easy. In this case, VSWR at the input terminal 1 or the output terminal 2 changes at the same time as the attenuation amount. This VSWR
In order to suppress the change in the voltage to a small value and to obtain a low VSWR characteristic, the variable resistance attenuator of the present invention has T
The resistance attenuator 13 is loaded. In the variable resistance attenuator which is one of the present invention shown in FIGS. 1 to 3, at least three resistors need to be short-circuited, whereas in the variable resistance attenuator of the present invention, at least one resistance is a short circuit. Since it is only necessary to short-circuit the resistor, it is very easy to adjust the amount of attenuation.

Embodiment 5 In Embodiment 4, a resistor 1 is placed between two T-type resistance attenuators 13.
Although the case where 4 and 15 are loaded is shown, the effect of using the T-type resistance attenuator 13 even if the resistors 14 and 15 are loaded between the two π-type resistance attenuators 16 as shown in FIG. Is the same.

As described above, by loading the resistors 14 and 15 between the two T-type resistance attenuators 13 or the two π-type resistance attenuators 16 and short-circuiting at least one of the resistors 14 and 15, The amount of attenuation can be easily changed. Therefore, by using these variable resistance attenuators in an amplifier, gain adjustment is very easy. Although the fourth and fifth embodiments have described the case where two T-type resistance attenuators 13 or two π-type resistance attenuators 16 are used, respectively, the variable resistance attenuator of the present invention may use more. The number of resistors loaded between the T-type resistance attenuators 13 and between the π-type resistance attenuators 16 may be one or two or more.

Embodiment 6 FIGS. 6 (a) and 6 (b) are an example of a structural diagram and a structural diagram of a variable resistance attenuator of the present invention. As shown in FIG. 6A, this variable resistance attenuator includes a resistance attenuator 19 in which resistors 18 are provided at both ends of a transmission line 17, and a resistance attenuator 22 in which resistors 21 are provided at both ends of a transmission line 20.
It is a configuration in which and are connected in cascade. The attenuation amount K when the resistor R is loaded in series with the load having the impedance Z ₀ is given by Equation 3 as shown in the fourth embodiment. In this case, if a large resistance R is used to obtain a large amount of attenuation, V
There is a problem that the SWR is greatly deteriorated. In order to avoid this, the resistance attenuator 19 has a configuration in which the resistors 18 are loaded at both ends of the transmission line 17, respectively. Transmission line 1
The characteristic impedance of 9 is usually selected to be 50Ω or an impedance lower than 50Ω, and the length thereof is selected to be approximately 1/4 wavelength in a desired frequency band. By selecting the characteristic impedance and the length of the transmission line 17 in this way, V
The resistance attenuator 19 having a good SWR can be configured, and the attenuation amount that is almost twice the attenuation amount shown in the equation 3 can be obtained. The resistance attenuator 22 is also similar to the resistance attenuator 19.

As described above, the variable resistance attenuator of the present invention has a structure in which two resistance attenuators 19 and 22 having a good VSWR are connected in cascade. For example, as shown in FIG. By short-circuiting, it is possible to change the attenuation amount of the microwave propagated from the input terminal 1 to the output terminal 2.

FIG. 6B shows an example of a structure in which the variable resistance attenuator of FIG. 6A is realized by a microwave integrated circuit. The transmission lines 17, 20, the resistors 18, 20 and the metal island 10 provided between the resistance attenuators 19 and 20 are integrally formed on the dielectric substrate 9. Further, it is easy to short-circuit the resistor 21 by connecting the metal island 10 and the transmission line 20 and connecting the transmission line 20 and the output terminal 2 with the metal thin wire 12, respectively. This type of variable resistance attenuator does not require grounding at one end of the resistor as in the embodiment of FIGS. 1 to 5, and has a very simple structure, but the band is limited by the transmission lines 17 and 20. .

As described above, the resistors 18 and 21 are provided at both ends of the transmission lines 17 and 20 having a length of about ¼ wavelength, respectively.
The resistance attenuators 19 and 22 which are also provided are connected in series,
By short-circuiting the resistor 18 of the resistance attenuator 19 or the resistor 21 of the resistance attenuator 22, the attenuation amount of the microwave propagating from the input terminal 1 to the output terminal 2 can be changed. Although this type of variable resistance attenuator is narrower in band than the first to fifth embodiments, one end of the resistor does not need to be grounded and the configuration is very simple. Therefore, this variable resistance attenuator can be used for adjusting the gain of the amplifier, and is particularly effective for an inexpensive amplifier whose band is not so wide. In addition,
In the above embodiment, the case where two resistance attenuators 19 and 22 are connected in series has been described, but the variable resistance attenuator of the present invention may use two or more resistance attenuators.

Embodiment 7 FIGS. 7 (a) and 7 (b) are still another example of the configuration and structure of the variable resistance attenuator of the present invention. This variable resistance attenuator has a structure in which resistors 18 and 21 are provided at both ends of a transmission line 17, as shown in FIG. The resistors 18 and 21 are selected so as to obtain a desired amount of attenuation, and the transmission line 17 is used to realize a low VSWR.
Has a characteristic impedance of 50Ω or lower than 50Ω, and a length of about 1/4 wavelength. In this variable resistance attenuator, it is possible to change the attenuation amount of the microwave propagating from the input terminal 1 to the output terminal 2 by short-circuiting both ends of the resistor 21 as shown in FIG. is there.

FIG. 7B is an example of a structural diagram when the variable resistance attenuator of FIG. 7A is constructed by using the microwave integrated circuit technology. The transmission line 17, the resistors 18, 21 and the metal island 10 provided between the resistors 18 and 21 are integrally formed on the dielectric substrate 9. For example, to short-circuit the resistor 21, the input terminal 1 and the metal island 10 are connected to each other. It is easy to connect the metal island 10 and the output terminal 2 with the thin metal wire 21 or the like. The variable resistance attenuator of the present invention includes one transmission line 1
7 and resistors 18 and 21, the configuration shown in FIG.
It is smaller than the sixth embodiment shown in (b), and it is not necessary to ground one end of the resistor and the configuration is very simple. However, if the values of the resistors 18 and 21 connected to both ends of the transmission line 17 are greatly changed in order to widen the variable range of the attenuation amount, VS
WR deteriorates. Therefore, it can be used as an attenuator having a relatively small variable range.

As described above, although the variable resistance attenuator has a slightly narrow variable range, it is small and has a very simple structure, and is effective for gain adjustment of a small and inexpensive amplifier. In the above embodiment, the case where two resistors 18 and 21 are connected to both ends of the transmission line 17 has been described, but in the variable resistance attenuator of the present invention, the transmission line 1
It may be a case where two or more resistors are connected to both ends of 7, respectively.

[0036]

As described above, according to the present invention, by dividing each of the three resistors forming the π-type or T-type resistance attenuator into a plurality of resistors and short-circuiting the predetermined resistors thus divided. , A variable resistance attenuator can be obtained. By using this attenuator for adjusting the gain of the amplifier, it is not necessary to prepare a large number of fixed T-type resistance attenuators with different attenuation amounts as in the conventional case, and it is not necessary to use them properly according to variations in gain. Significant reduction of time and production cost can be achieved. Since this attenuator is small and has flat attenuation characteristics over a wide band, it is particularly effective for adjusting the gain of a wide band amplifier.

In the variable resistance attenuator of the present invention, at least two π type or T type resistance attenuators are connected in series,
At least one resistor is provided between the cascade-connected attenuators, and the resistor is short-circuited to change the attenuation amount. This variable resistance attenuator has an attenuation amount that can be easily varied by short-circuiting at least one resistor, and has a flat attenuation characteristic over a wide band, so that it is particularly effective for adjusting the gain of an inexpensive wide band amplifier. .

Further, in the variable resistance attenuator of the present invention, a plurality of resistance attenuators each having one resistance connected in series are connected in series at both ends of a transmission line having a length of about 1/4 wavelength. The attenuation amount is variable by short-circuiting the resistance of a predetermined resistance attenuator. This variable resistance attenuator does not need to short one end of the resistor,
Since the configuration is very simple, it is particularly effective for adjusting the gain of an amplifier that is inexpensive and does not have a wide band.

Further, in the variable resistance attenuator of the present invention, a plurality of resistors are connected in series at both ends of a transmission line having a length of about 1/4 wavelength, and among these resistors,
The amount of attenuation is made variable by short-circuiting a predetermined resistor. Although this variable resistance attenuator has a slightly narrow variable range, it is relatively small in size and has a very simple structure, so that it is particularly effective for gain adjustment of a small and inexpensive amplifier whose band is not so wide.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a variable resistance attenuator configured by dividing a resistance of a T resistance attenuator according to an embodiment of the present invention.

FIG. 2 is an example of a structural diagram of a variable resistance attenuator according to an embodiment of the present invention shown in FIG.

FIG. 3 is a configuration diagram of a variable resistance attenuator configured by dividing the resistance of a π resistance attenuator according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a variable resistance attenuator constructed by loading a resistor between T-type resistance attenuators according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a variable resistance attenuator constructed by loading a resistance between π type resistance attenuators according to another embodiment of the present invention.

6A and 6B are a configuration diagram and a structural diagram of a variable resistance attenuator configured by cascade-connecting resistance attenuators which is still another embodiment of the present invention.

7A and 7B are a structural diagram and a structural diagram of a variable resistance attenuator, which is a further embodiment of the present invention, in which a plurality of resistors are provided at both ends of a transmission line.

FIG. 8 is a configuration diagram of a conventional T-type resistance attenuator.

[Explanation of symbols]

 1 Input Terminal 2 Output Terminal 3 Resistance 4 Resistance 5 Resistance 6 Resistance 9 Dielectric Substrate 10 Metal Island 11 Grounding Conductor 12 Metal Fine Wire 13 T-Type Resistance Attenuator 14 Resistance 15 Resistance 16 π-Type Resistance Attenuator 17 Transmission Line 18 Resistance 19 Resistance Attenuator 20 transmission line 21 resistance 22 resistance attenuator

Claims (4)

[Claims] 1. Attenuation amount of microwave by dividing each of the three resistors forming the π-type or T-type resistance attenuator into a plurality of resistors and short-circuiting a predetermined resistor among the divided resistors. A variable resistance attenuator characterized in that it is possible to change. 2. At least two π-type or T-type resistance attenuators are connected in series, and at least 1 is provided between the resistance attenuators.
A variable resistance attenuator characterized in that the attenuation of microwaves can be changed by providing at least one resistor and by shorting the resistors. 3. A plurality of resistance attenuators each having one resistance connected in series are connected in series at both ends of a transmission line having a length of about ¼ wavelength, and the predetermined resistance attenuator is provided. A variable resistance attenuator characterized in that the amount of microwave attenuation can be changed by short-circuiting the resistance of. 4. A plurality of resistors are connected in series at both ends of a transmission line having a length of about ¼ wavelength, and
A variable resistance attenuator characterized in that the amount of microwave attenuation can be changed by short-circuiting a predetermined resistance of the plurality of resistances.