JP3912623B2 - Attenuator and equipment - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a high-frequency π-type attenuator suitable for mobile communication devices such as mobile phones and other high-frequency and microwave-band electrical devices, and more particularly to a control voltage of a π-type voltage control attenuator using a PIN diode. The present invention relates to a π-type attenuator and equipment for linearizing attenuation characteristics.
[0002]
[Prior art]
In general, an attenuator is used in a mobile communication device such as a cellular phone and other high-frequency and microwave electric devices. An example of this type of conventional attenuator is a π-type attenuator 1 shown in FIG. .
[0003]
In this π-type attenuator 1, for example, four PIN diodes D 1, D 2, D 3, D 4 are arranged in a π-type, and a constant DC bias voltage is applied to the bias terminal 2 while applied to the control terminal 3. By controlling the DC voltage Vc for various purposes, the internal resistance of each of the PIN diodes D1 to D4 is controlled, and the attenuation amount of the high frequency signal RF such as a microwave input from the input terminal IN and output from the output terminal OUT is controlled. Various controls are provided.
[0004]
However, in this π-type voltage control attenuator 1 as shown in FIG. 5, the attenuation ATT (dB) changes nonlinearly as shown by the curve A with respect to the control voltage Vc, and particularly in the rising region of the attenuation characteristic. Since the amount of attenuation increases sharply with respect to a slight change in the control voltage Vc, there is a problem that it is not always easy to control the amount of attenuation ATT with the control voltage Vc.
[0005]
Therefore, conventionally, as shown in FIG. 6, in the middle of a current path 3b connecting the control terminal 3 of the π-type voltage control attenuator 1 and the intermediate connection point 3a between the first and second PIN diodes D2 and D3. The attenuation characteristic is linearized by interposing a broken line approximation type linearizer circuit 4.
[0006]
This linearizer circuit 4 operates a plurality of transistors Q1, Q2,..., Qn sequentially in a stepwise manner according to the magnitude of the control voltage Vc, so that the control current Ic applied to the attenuator 1 is nonlinear in the attenuation characteristic of the attenuator 1. Is controlled individually in each stage so that the signal is linearized in multiple stages.
[0007]
[Problems to be solved by the invention]
However, in such a conventional linearizer circuit 4, in order to linearize the nonlinearity of the attenuation characteristic with respect to the control voltage Vc, each operating point of all the transistors Q1 to Qn is operated stepwise by each variable resistor Rv. Therefore, there is a problem that there are many adjustment points and it is troublesome. Further, in order to increase the linearization accuracy, it is necessary to provide the transistors Q1 to Qn in multiple stages, which causes an increase in the number of parts and a complicated configuration.
[0008]
Therefore, the present invention has been made in consideration of such circumstances, and the object of the present invention is to easily linearize the non-linearity of the attenuation characteristic with respect to the control voltage of the π-type voltage control attenuator with a simple configuration, thereby easily and increasing the attenuation. An object of the present invention is to provide an attenuator that can be controlled with high accuracy and a device including the attenuator.
[0009]
[Means for Solving the Problems]
The present invention is configured as follows to solve the above problems.
[0010]
The invention according to claim 1 of the present application is a PIN diode circuit formed by connecting a plurality of PIN diodes in a π shape, bias means for applying a constant DC voltage to the PIN diode circuit, and a control voltage applied to the PIN diode circuit. An attenuator body circuit having control means for controlling the attenuation of the AC input signal by applying and controlling the internal resistance of the PIN diode, and a forward direction inserted in series between the control means and the PIN diode circuit And a parallel circuit of a diode and a resistor.
[0011]
Note that the diode of the parallel circuit includes a silicon PN junction diode, a silicon Schottky diode, and a germanium diode.
[0012]
According to the present invention, when the direct current control current supplied from the control means to the PIN diode circuit is equal to or less than the predetermined value, the current flows toward the resistance of the parallel circuit, but the voltage drop at the resistance is the resistance of the diode of the parallel circuit. When the forward voltage is exceeded, this diode turns on (conducts) and flows into the PIN diode circuit.
[0013]
Since the control current when the diode of this parallel circuit is conductive gradually rises with a gentle curve with respect to the control voltage due to the forward direction VI characteristic of this diode, the attenuator body circuit has a steep attenuation characteristic due to this rising region. Start-up can be relaxed and linearized. As a result, the attenuation amount of the attenuator can be easily and accurately controlled by the control voltage.
[0014]
In addition, since the forward voltage drop of the diode is small, when the present invention is incorporated in an electronic device such as a battery-driven mobile phone, for example, low voltage / low power driving is possible.
[0015]
Since the parallel circuit having the linearization function is simply composed of a parallel circuit of a diode and a resistor, the configuration is simple, and it is possible to reduce both the number of parts and the cost. Further, there is no need to adjust the operating point and the adjustment work can be omitted.
[0016]
Furthermore, if the resistance value of the resistor of the parallel circuit is set high, the current change before the diode is turned on can be moderated arbitrarily. Thereby, the change of the attenuation amount of the attenuator can be arbitrarily moderated.
[0017]
The invention according to claim 2 of the present application is characterized in that the diode is a silicon junction type diode.
[0018]
According to the present invention, since the diode is a silicon junction type diode, the attenuator is controlled by a higher resistance in the rising region of the control current flowing in the forward direction of the diode and the gentleness of the rising region of the forward VI characteristic of the diode. The steep portion can be linearized easily corresponding to the steep rising region of the attenuation characteristic of the main circuit.
[0019]
The invention according to claim 3 of the present application is characterized by comprising the attenuator according to claim 1 or 2 and a device main body incorporating an electric circuit including the attenuator.
[0020]
According to the present invention, the device such as the mobile phone is provided with the attenuator according to claim 1 or 2 which can control the attenuation amount easily and with high accuracy. Can be controlled easily and with high accuracy.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
[0022]
FIG. 1 is an electronic circuit diagram of an embodiment of the present invention. In this figure, an attenuator 11 is provided with a linearizer circuit 13 which is a parallel circuit in a π-type voltage control attenuator body circuit 12.
[0023]
The attenuator main body circuit 12 is configured in the same manner as the conventional attenuator 1 shown in FIG. 4, for example, a PIN diode circuit 12a in which four PIN diodes D1, D2, D3, D4 are arranged and connected in a π shape. The internal resistance of each of the PIN diodes D1 to D4 is controlled by variously controlling the bias means for applying a constant DC bias voltage to the bias terminal 14 and the control DC voltage Vc applied to the control terminal 15; And control means for variously controlling the attenuation amount of the high frequency signal RF such as a microwave input from the input terminal IN and output from the output terminal OUT.
[0024]
The linearizer circuit 13 includes a parallel circuit of a resistor 16 and a diode 17 such as a silicon PN junction, and a current path 19 connecting the control terminal 15 of the attenuator body circuit 12 and the connection point 18 of the PIN diodes D2 and D3. It is comprised by interposing in the middle.
[0025]
FIG. 2 shows the forward VI characteristic of the linearizer diode 17, which indicates that the forward current I that flows when the voltage V is applied in the forward direction has a predetermined voltage drop (for example, a silicon PN junction). However, the forward current I has a feature that the forward current I increases very slowly as the forward voltage V increases.
[0026]
Next, the operation of this embodiment will be described.
[0027]
When the DC control current Ic flowing through the energization path 19 of the control terminal 15 is smaller than a predetermined value, that is, when the control current Ic flows through the linearizer resistor 16, the voltage drop of the linearizer diode 17 is a predetermined voltage. When it is smaller than the drop, it flows through the linearizer resistor 16 side and flows into the PIN diode circuit 12a.
[0028]
When the voltage drop at the linearizer resistor 16 exceeds a predetermined voltage drop of the linearizer diode 17, the diode 17 is turned on (conducted), so that the control current Ic flows through the diode 17 and PIN It flows into the diode circuit 12a. In the region where the control current Ic flows only on the resistor 16 side (C region in FIG. 3), the change of the attenuator attenuation can be arbitrarily moderated by appropriately setting the resistance value. Further, when the control current Ic flows through the linearizer diode 17 side, the attenuation change can be further linearized by the rising portion B of the forward direction VI characteristic of the diode 17.
[0029]
With the above configuration, as shown in FIG. 3, the inclination of the steep portions Ao and A1 where the attenuation amount ATT (dB) suddenly increases with respect to the control voltage Vc is relaxed, and the nonlinearity of this attenuation characteristic is linearized as a whole. Can do. Note that the number of linearizer diodes 17 is not necessarily one, and may be one or more. The diode 17 may be a Schottky diode or a germanium diode. Since these diodes have a small voltage drop, they are advantageous because they can be driven at low voltage and low power when incorporated in electronic devices such as battery-powered mobile phones.
[0030]
Then, by providing the attenuator 11 thus configured in a mobile phone, mobile telecommunications equipment, other high-frequency or microwave electrical equipment, etc., the amount of attenuation of the electrical signal is not increased. Can be controlled with high precision and ease.
[0031]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the control current supplied from the control means to the PIN diode circuit flows through the resistance of the parallel circuit, and further continues to flow through the diode side, the control current is the magnitude of the resistance value of this resistance, Since the diode gradually rises with a gentle curve with respect to the control voltage due to the forward VI characteristics of the diode, this rising region can be used to relax and linearize the steep rise of the attenuation characteristic of the attenuator body circuit. . As a result, the attenuation amount of the attenuator can be easily and accurately controlled by the control voltage.
[0032]
In addition, since the forward voltage drop of the diode is small, when the present invention is incorporated in an electronic device such as a battery-driven mobile phone, for example, low voltage / low power driving is possible.
[0033]
Since the parallel circuit having the linearization function is simply composed of a parallel circuit of a diode and a resistor, the configuration is simple, and it is possible to reduce both the number of parts and the cost. Further, the operating point of the diode can be adjusted only by the resistance value of the parallel circuit, and the adjustment work is very simple.
[0034]
According to the second aspect of the present invention, when the diode is a silicon junction type diode, the forward rising voltage is larger than other diodes such as a Schottky diode and a germanium diode. it can. That is, it is advantageous to moderate the change in the attenuation amount when the current flows only on the resistance side.
[0035]
According to the invention of claim 3, since the device such as a portable telephone device is provided with the attenuator according to claim 1 or 2 capable of easily controlling the attenuation, the attenuation of the input signal or the like is provided as the device. Can be controlled with high accuracy.
[Brief description of the drawings]
FIG. 1 is an electronic circuit diagram of an attenuator according to an embodiment of the present invention.
FIG. 2 is a forward VI characteristic diagram of the linearizer diode shown in FIG. 1;
FIG. 3 is a diagram showing a state in which the attenuation characteristic of the attenuator body circuit is linearized by the linearizer circuit shown in FIG. 1;
FIG. 4 is an electronic circuit diagram of a conventional π-type voltage control attenuator.
5 is an attenuation characteristic diagram of the attenuator shown in FIG. 4. FIG.
FIG. 6 is a partially omitted electronic circuit diagram of a conventional linearizer circuit.
[Explanation of symbols]
11 Attenuator 12 Attenuator body circuit 13 Linearizer circuit (parallel circuit)
14 Bias terminal 15 Control terminal 16 Linear riser resistor 17 Linear riser diode 18 Intermediate connection point 19 Current path

Claims (3)

A PIN diode circuit formed by connecting a plurality of PIN diodes in a π shape, bias means for applying a constant DC voltage to the PIN diode circuit, and applying a control voltage to the PIN diode circuit to reduce the internal resistance of the PIN diode An attenuator body circuit having control means for controlling the attenuation of the AC input signal by controlling;
A parallel circuit of a forward diode and a resistor inserted in series between the control means and the PIN diode circuit;
An attenuator characterized by comprising: 2. The attenuator according to claim 1, wherein the diode is a silicon junction type diode. The attenuator according to claim 1 or 2,
A device body containing an electric circuit including the attenuator;
A device characterized by comprising:

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