KR20060108858A - Wireless communication terminal having flexible printed circuit board with function of filtering - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a wireless communication terminal having a flexible printed circuit board having a filtering function.

2. The technical problem to be solved by the invention

The present invention, by implementing the data line of the flexible printed circuit board for transferring data from the main body of the wireless communication terminal to the data receiving means (for example, LCD) in the form of a microstrip filter to perform a filtering function, radiation according to high-speed data transmission It is an object of the present invention to provide a wireless communication terminal having a flexible printed circuit board having a filtering function, which can improve the sensitivity degradation of the wireless communication terminal due to noise.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided a wireless communication terminal, comprising: central processing means for driving the wireless communication terminal and processing data to be transmitted to a data receiving means; Connecting means for physically connecting the data received from the central processing means with a flexible printed circuit board having a filtering function; A plurality of data lines implemented with a microstrip filter to filter the noise of data received from the connection means and to transmit the noise to the data receiving means; And the data receiving means for receiving data received through the flexible printed circuit board.

4. Important uses of the invention

The present invention is used in a wireless communication terminal.

Microstrip, Radiated Noise, Filters, Flexible Printed Circuit Boards (FPCBs), Wireless Communication Terminals

Description

Wireless communication terminal having flexible printed circuit board with filtering function

1 is a configuration diagram of an embodiment of a conventional wireless communication terminal;

2 is a configuration diagram of a wireless communication terminal having a flexible printed circuit board having a filtering function according to the present invention;

Figure 3 is an embodiment of a microstrip filter used in the present invention,

4 is a diagram showing an equivalent circuit of the microstrip filter used in the present invention;

5 is a graph showing the characteristics of the microstrip filter used in the present invention.

* Explanation of symbols for the main parts of the drawings

21: central processing unit 22: LCD connection

23: flexible printed circuit board (FPCB) 24: display (LCD)

The present invention relates to a wireless communication terminal having a flexible printed circuit board having a filtering function, and more particularly, to a data of a flexible printed circuit board for transferring data from a main body of the wireless communication terminal to a data receiving means (for example, an LCD). By implementing the line in the form of a microstrip filter to perform a filtering function, the wireless communication with a flexible printed circuit board having a filtering function, which can improve the sensitivity deterioration of the wireless communication terminal due to radiation noise due to high speed data transmission. It relates to a terminal.

In the present invention, a wireless communication terminal is a mobile communication terminal, a personal digital communication terminal (PCS), a personal digital terminal (PDA), a smart phone, a next generation mobile communication terminal (IMT-2000), wireless communication while being carried by an individual such as a wireless LAN terminal. Say this is possible terminal.

In the present invention, microstrip is a circuit type for implementing a distributed circuit for high frequency, and is widely used in RF and microwave. Microstrip is a circuit structure in which a ground is completely laid on the bottom and only a signal line is disposed on the top to transmit a signal between the signal line and the ground. Microstrips are often mistaken for board names, not just the type of board, but a way of implementing circuit patterns. However, due to the high frequency characteristics, it is implemented as a general printed circuit board (PCB), and there is a problem of loss and performance.

Flexible printed circuit boards (FPCBs), meanwhile, are flexible printed circuit boards (PPCs) with copper foil on a thin insulating film (PI, polyimide) with a thickness of 10 µm. It is attracting attention as a core board for high-performance small electronic devices because of its advantages of wiring and three-dimensional wiring. Moreover, it is excellent in workability, and is strong in heat resistance, grain resistance, and chemical resistance.

Flexible printed circuit boards are developed as electronic products become smaller and lighter, and are widely used in cameras, computers and peripherals, wireless communication terminals, video and audio devices, camcorders, printers, TFT LCDs, satellite equipment, military equipment, and medical equipment.

1 is a configuration diagram of an embodiment of a conventional wireless communication terminal.

As shown in FIG. 1, the conventional wireless communication terminal drives the wireless communication terminal, and includes a central processing unit 11 for processing data to be transmitted to the display unit 17, from the central processing unit 11 for each line. The first to third filters 12 to 14 to remove noise (noise) of the received data, and the data received from the first to third filters 12 to 14 to the flexible printed circuit board 16 and ( Physically) LCD connection unit 15 for connection, a flexible printed circuit board (FPCB) 16 for transferring data received from the LCD connection unit 15 to the display unit (LCD), and the flexible printed circuit board 16 It includes a display unit (LCD) (17) for displaying the data received through.

The conventional wireless communication terminal uses a modular filter 12 to 14 at the front end of the LCD connection unit 15 before data is transferred to the flexible printed circuit board 16 for connecting the central processing unit 11 and the display unit 17. To remove noise.

That is, as shown in FIG. 1, when there are multiple data lines, a separate filter for transferring to the display unit 17 is required because a filter having a different characteristic is required for each data line.

In addition, since the data is transferred to the display unit 17 through the flexible printed circuit board 16 from the central processing unit 11 located in the printed circuit board (PCB) of the main body of the wireless communication terminal in a high speed of GSM and DCS bands. There is a problem that noise is radiated to lower the sensitivity of the wireless communication terminal.

The present invention has been proposed to solve the above problems, and implements a filtering function by implementing a data line of a flexible printed circuit board that transfers data from a main body of a wireless communication terminal to a data receiving means (for example, an LCD) in the form of a microstrip filter. It is an object of the present invention to provide a wireless communication terminal having a flexible printed circuit board having a filtering function, which can improve the sensitivity deterioration of the wireless communication terminal due to radiation noise due to high speed data transmission.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

An apparatus of the present invention for achieving the above object is a wireless communication terminal, comprising: central processing means for processing data to be transmitted to a data receiving means for driving the wireless communication terminal; Connecting means for physically connecting the data received from the central processing means with a flexible printed circuit board having a filtering function; A plurality of data lines implemented with a microstrip filter to filter the noise of data received from the connection means and to transmit the noise to the data receiving means; And the data receiving means for receiving data received through the flexible printed circuit board.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an embodiment of a wireless communication terminal having a flexible printed circuit board having a filtering function according to the present invention.

As shown in FIG. 2, a wireless communication terminal having a flexible printed circuit board having a filtering function according to the present invention drives the wireless communication terminal and has a central processing unit for processing data to be transmitted to the display unit 24. 21), the LCD connection unit 22 for physically connecting the data received from the central processing unit 21 with the flexible printed circuit board filter 23, a plurality of data lines in the form of a microstrip filter (not shown) Implemented to be a flexible printed circuit board 23 for filtering the noise of the data transmitted from the LCD connection unit 22 to the display unit (LCD) 24, received through the flexible printed circuit board filter 23 And a display portion (LCD) 24 for displaying data.

That is, the plurality of data lines located in the flexible printed circuit board 23 are implemented in the form of a microstrip filter (pattern). Hereinafter, one microstrip filter will be described as an example.

3 is a diagram illustrating an embodiment of a microstrip filter used in the present invention.

As shown in FIG. 3, the microstrip filter used in the present invention is connected to the first transmission line 31 and the first transmission line 31 for impedance matching with an input terminal to serve as a first inductor. The second transmission line 32 for connecting, the third transmission line 33 for connecting to the second transmission line 32 to serve as a capacitor and the third transmission line 33 to serve as a second inductor And a fourth transmission line 34 connected to the fourth transmission line 34 and a fifth transmission line 35 for impedance matching between the signal and the output terminal received from the fourth transmission line 34. do.

The thickness of each microstrip line is W1 to W5, and the length is L1 to L5.

In general, higher impedance lines act as inductors and lower impedance lines act as capacitors based on matching lines. 3, it can be considered as a 3rd order filter.

When each transmission line is converted into an equivalent circuit, the first transmission line 31 and the fifth transmission line 35 are resistors, and the second transmission line 32 and the fourth transmission having a higher impedance than the matching line and having a higher impedance are used. Line 34 is an inductor, and the third transmission line 33, which is wider than the matching line and has a lower impedance, operates as a capacitor.

Looking at the design process of the microstrip filter used in the present invention.

First of all, in designing a low pass filter with a cutoff frequency of 700 MHz and a matching impedance of 50 ohms, the design of the filter formally is too complex and is outside the range of flexible printed circuit board sizes that can be applied to wireless terminals. Can be.

Therefore, the length is limited so that the sum of the total lengths does not exceed 10 cm, and the width of the filter is limited to within 2 mm.

The length of L1, L5, W1, W5 is fixed and the length of L2, L3, L4, W2, W3, W4 is adjusted to meet the length limit and thickness limit conditions, and the overall length is within 8 cm and the length of each transmission line The best performance within 2 mm width was obtained using simulation.

4 is a diagram showing an equivalent circuit of the microstrip filter used in the present invention.

As shown in FIG. 4, the equivalent circuit of the microstrip filter used in the present invention includes a first resistor 41 and a first resistor connected to the first resistor 41 to match the impedance of the input terminal (50 ohms). Connected to the inductor 42, the capacitor 43 connected to the first inductor 42, the second inductor 44 connected to the capacitor 43, and the second inductor to match the impedance of the output terminal (50 ohms) It includes a second resistor 45 to.

Meanwhile, in the present invention, a third order (LPF) low pass filter (LPF) is used due to the spatial constraints of the flexible printed circuit board. It is not limited.

5 is a graph showing the characteristics of the microstrip filter used in the present invention.

As shown in FIG. 5, the characteristics of the microstrip filter used in the present invention show that the cutoff frequency is 700 MHz and S11 is sufficiently low.

The graph of FIG. 5 is obtained by simulation by a commercial simulation program "ADS" (Advansed Design System) of Hewlett Packard (HP), and the thickness (W) and the length (L) of each transmission line at this time are as follows.

1st transmission line-W1: 1 mm, L1: 5 mm

2nd transmission line-W2: 0.08 mm, L2: 20 mm

3rd transmission line-W3: 1.3 mm, L3: 20 mm

4th transmission line-W4: 0.08 mm, L4: 20 mm

5th transmission line-W5: 1 mm, L5: 5 mm

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above, by implementing the data line of the flexible printed circuit board for transferring data from the main body of the wireless communication terminal to the data receiving means (for example, LCD) in the form of a microstrip filter to perform a high-speed data transmission There is an effect that can improve the sensitivity degradation of the wireless communication terminal due to the radiation noise.

Claims (3)

In a wireless communication terminal, Central processing means for driving the wireless communication terminal and processing data to be transmitted to the data receiving means; Connecting means for physically connecting the data received from the central processing means with a flexible printed circuit board having a filtering function; A plurality of data lines implemented with a microstrip filter to filter the noise of data received from the connection means and to transmit the noise to the data receiving means; And The data receiving means for receiving data received through the flexible printed circuit board Wireless communication terminal having a flexible printed circuit board having a filtering function comprising a. The method of claim 1, The microstrip filter of the flexible printed circuit board, A wireless communication terminal having a flexible printed circuit board having a filtering function, characterized in that it is a low pass filter (LPF). The method according to claim 1 or 2, The microstrip filter, A first transmission line for impedance matching with an input terminal; A second transmission line connected to the first transmission line to serve as a first inductor; A third transmission line connected to the second transmission line to serve as a capacitor; A fourth transmission line connected to the third transmission line to serve as a second inductor; And A fifth transmission line connected to the fourth transmission line for impedance matching between an output terminal and a signal received from the fourth transmission line Wireless communication terminal having a flexible printed circuit board having a filtering function comprising a.

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