JPH06350472A - Matching circuit - Google Patents

Abstract

PURPOSE:To easily perform automatic adjustment with high reliability even after assembling by providing a variable capacitance diode as an element for adjustment to perform the automatic adjustment for a matching state. CONSTITUTION:This matching circuit 8 is connected between an intermediate frequency filter 2 and a frequency converter 1 at the reception part of mobile radio equipment such as a portable telephone, etc., and it comprises the variable capacitance diode 10 as the element for adjustment of the matching circuit 8 whose one terminal is connected to the frequency converter 1 and whose other terminal to the ground 9, and a mutual inductance (primary and secondary coils) 7 whose one terminal is connected to the frequency converter 1 and whose other terminal to the intermediate filter 2. In such a case, the automatic adjustment can be performed after the assembling by applying a DC voltage in a reverse direction to the variable capacitance diode 10 and performing the adjustment of the matching state of the matching circuit 8 by a control part 12 according to data stored in memory 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matching circuit for a high frequency tuning circuit and an intermediate frequency filter used in a receiving section of a mobile radio such as a mobile phone. The present invention relates to a matching circuit that can easily and automatically perform automatic adjustment even afterward.

[0002]

2. Description of the Related Art Generally, an intermediate wave filter is used in a receiver of a mobile radio such as a mobile phone, and a relatively narrow band filter such as an MCF or a crystal filter is used as the intermediate frequency filter. There is. A circuit using an active element such as an amplifier or a frequency converter is usually connected to the front and rear stages of these filters. However, since the impedances of this circuit and the intermediate frequency filter are different from each other, the filter The desired characteristics cannot be obtained. Therefore, a matching circuit is inserted between the two to match them. This matching circuit is generally composed of an LC network and is adapted to make the matching state better.

FIG. 3 shows a typical conventional example of a matching circuit for an intermediate frequency filter used in a mobile radio device or the like.

In FIG. 3, a first matching circuit 3 is connected between a frequency converter 1 for converting a reception signal to an intermediate frequency and an intermediate frequency filter 2, and the intermediate frequency filter 2 and the intermediate frequency filter 2 are connected. A second matching circuit 5 is connected between the second matching circuit 5 and the amplifier 4 which amplifies the intermediate frequency signal from the filter 2.

Each of the first and second matching circuits 3 and 5 is composed of an LC network having a capacitance (capacitor) 6 and a mutual inductance (primary and secondary coil) 7. The first and second matching circuits 3 and 5 improve the matching state between the frequency converter 1 and the intermediate frequency filter 2 or between the intermediate frequency filter 2 and the amplifier 4, The adjustment was performed using one of the following two methods. (1) A method of adjusting the mutual inductance 7 by varying it. (2) A method in which the capacitance 6 is varied and adjustment is performed.

Here, the above method (1) is carried out by providing a magnetic core inside or outside a primary or secondary coil having a bobbin wound, and changing the mechanical position of the core. The above method (2) has been carried out by using a capacitor having a mechanical rotating part called a trimmer capacitor. However, these methods have the drawbacks described below. (1) Each person must make adjustments by hand, and automatic adjustment cannot be performed. (2) Since there are adjustment parts inside the housing, it cannot be adjusted after assembly. In addition, the lid and P covering the adjustment parts
The adjustment points differ depending on the presence or absence of the lid depending on the play capacity between CBs. (3) The adjustment parts are expensive. (4) Since it has a movable part, it is susceptible to shock and vibration and changes over time. The same problem also exists in the filter and tuning circuit of the receiving high frequency section, and automatic adjustment and adjustment means after assembly have been desired.

[0007]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a matching circuit that can easily and automatically perform automatic adjustment even after assembly.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is a matching circuit for a receiving high frequency tuning circuit or an intermediate frequency filter used in a receiving section of a mobile radio device. A variable capacitance diode is provided as an adjusting element for performing automatic adjustment.

[0009]

The present invention will be described below based on the illustrated embodiments. FIG. 1 is a block diagram showing an embodiment of a matching circuit according to the present invention. In FIG. 1, the matching circuit 8 is connected between the intermediate frequency filter 2 and the frequency converter 1 in the receiving unit of a mobile radio such as a mobile phone, and one end of the matching circuit 8 is connected to the frequency converter 1. A variable capacitance diode 10 as an adjusting element of the matching circuit 8 whose end is connected to the ground 9, and a mutual inductance (one end of which is connected to the frequency converter 1 and the other end of which is connected to the intermediate frequency filter 2) ( Primary and secondary coils) 7. The capacitance of the variable-capacitance diode 10 changes according to the magnitude of the reverse direct-current voltage applied to the variable-capacitance diode 10, whereby the matching state between the frequency converter 1 and the intermediate frequency filter 2 is changed. Adjustments are made to improve.

Here, the adjustment is performed by the controller 12 applying a DC voltage to the variable capacitance diode 10 via the D / A converter 13 and the resistor 14 in accordance with the data stored in advance in the memory 11. . Here, the memory 11, the control unit 12, the D / A converter 13, and the resistor 14 are provided in advance in the mobile radio device. That is, as the control unit 12, a microcomputer provided in advance for controlling the inside of the mobile wireless device is borrowed only at the time of adjustment.

Next, the adjusting operation of the matching circuit will be described with reference to FIG. Matching circuit 8 in the mobile radio device
In order to adjust the above, first, a measuring device 15 for measuring the characteristics of the radio is connected to the mobile radio, and
A controller 16 for communicating with the control unit 12 in the radio is connected. Then, while observing the characteristics of the wireless device measured by the measuring device 15, the controller 1
6 communicates with the control unit 12 to change the reverse DC voltage to the variable capacitance diode 10 in the matching circuit 8 from the control unit 12 so that the characteristics of the radio device can be optimized. The capacitance of the variable-capacitance diode 10 is changed, and the data when the characteristic is the best is stored in the memory 11. Then, after assembling the set, the control unit 12 applies a reverse DC voltage to the variable capacitance diode 10 according to the data stored in the memory 11,
If the matching state of the matching circuit 8 is adjusted, automatic adjustment can be achieved. That is, according to the above method, since most recent wireless devices have a built-in microcomputer and memory with the mobile phone as the first device, it is not necessary to add any new hardware to perform the above operation. Since the variable capacitance diode is cheaper than the conventional movable part, the automatic adjustment can be achieved at a very low cost. In the above embodiment, the matching circuit of the intermediate frequency filter in the mobile wireless device has been described.
It is needless to say that the present invention is not limited to this, and can be applied to a receiving high frequency circuit, other communication devices and electric devices.

[0012]

As described above, the present invention provides a method of using a variable capacitance diode for adjusting the matching state of a matching circuit, storing the DC applied voltage as data in a memory, and generating it by a D / A converter. Therefore, the matching circuit can be automatically adjusted with high reliability and at low cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a matching circuit according to the present invention.

FIG. 2 is an explanatory diagram showing an adjusting operation of the matching circuit shown in FIG.

FIG. 3 is a diagram showing a typical conventional example of a matching circuit for an intermediate wave filter.

[Explanation of symbols]

1 ... Frequency converter, 2 ... Intermediate frequency filter, 3, 5 ... First and second matching circuits,
4 ... Amplifier, 6 ... Capacitance, 7 ... Mutual inductance (primary and secondary coil), 8 ... Matching circuit according to the present invention, 9 ... Ground, 10 ... Variable capacitance diode, 11 ... Memory, 12 ... Control section , 13 ... D / A converter, 14 ... resistor,

Claims (3)

[Claims] 1. A matching circuit for a receiving high frequency tuning circuit or an intermediate frequency filter used in communication equipment, comprising:
A matching circuit comprising a variable capacitance diode as an adjusting element for adjusting a matching state by the matching circuit. 2. The adjustment of the matching state is performed by applying a reverse DC voltage, which is determined based on a stored data value, to the variable capacitance diode. Matching circuit. 3. The matching circuit according to claim 2, wherein a microcomputer in the communication device is used as the control means for applying the reverse DC voltage.