JP4130288B2 - Front-end module for triple-band mobile phones - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a front-end module in a mobile phone that is also used for three communication methods.
[0002]
[Prior art]
For example, Japanese Laid-Open Patent Publication No. 11-225088 discloses a front-end module for a dual-band mobile phone of GSM and DCS system in Europe. This is a module that switches between transmission and reception of two different communication methods. 4A is a block diagram of the module, in which 20 is a front-end module, 1 and 2 are low frequency band side reception circuits and transmission circuits, and 3 and 4 are high frequency band side reception circuits and transmission circuits, respectively. It is.
[0003]
The front-end module 20 includes a diplexer 6 as a demultiplexing circuit that is connected to the antenna 5 and separates signals into a low frequency band and a high frequency band, a low frequency band antenna switch 7, and a high frequency band antenna switch 8, respectively. It consists of low-pass filters 10 and 11 for removing harmonics connected to the transmission circuits 2 and 4. The low frequency band antenna switch 7 and the low pass filter 10 are connected to the low frequency band receiving circuit 1 and the transmitting circuit 2 via terminals RX1 and TX1, respectively. The high frequency band antenna switch 8 and the low pass filter 11 are connected to the high frequency band reception circuit 3 and the transmission circuit 4 via terminals RX2 and TX2, respectively.
[0004]
FIG. 5 is an equivalent circuit diagram of the front end module of FIG. In FIG. 5, the low frequency band notch circuit 12 constituting the diplexer 6 includes capacitors C1 and C3 and an inductor L1. The high frequency band notch circuit 13 includes a capacitor C2 and inductors L2 and L3.
[0005]
T11 is a connection terminal connected to the low frequency band transmission circuit 2, and corresponds to the terminal TX1 in FIG. The harmonic removal low pass filter 10 includes capacitors C4 to C6 and an inductor L4. T7 is a terminal connected to the receiving circuit 1, and corresponds to the terminal RX1 in FIG. The low-frequency band antenna switch 7 is inserted between the notch circuit 12 and the low-pass filter 10, and a bias terminal T10 for applying a switching bias voltage, capacitors C7 to C10, inductors L5 and L6, a resistor R1, It consists of diodes D1 and D2.
[0006]
T1 is a connection terminal connected to the high frequency band transmission circuit 4 and corresponds to the terminal TX2 in FIG. The harmonic removal low-pass filter 11 includes capacitors C16 to C18 and an inductor L10. T5 is a connection terminal connected to the receiving circuit 3, and corresponds to the terminal RX2 in FIG. The high frequency band antenna switch 8 is inserted between the notch circuit 13 and the low-pass filter 11, and applies a bias terminal T2 for applying a switching bias voltage, capacitors C11 to C15, inductors L7 to L9, a resistor R2, It consists of diodes D3 and D4.
[0007]
In this equivalent circuit, when a bias is applied to the bias terminal T10 of the low frequency band antenna switch 7 to operate the diodes D1 and D2, the transmission circuit connection terminal T11 and the antenna 5 are connected. On the other hand, when the bias terminal T10 is not biased or is reversely biased, the receiving circuit connection terminal T7 and the antenna 5 are connected.
[0008]
Also in the high frequency band antenna switch 8, when a bias is applied to the bias terminal T2 of the high frequency band antenna switch 8 to operate the diodes D3 and D4, the transmission circuit connection terminal T1 and the antenna 5 are connected. On the other hand, when the bias terminal T2 is not biased or is reversely biased, the receiving circuit connection terminal T5 and the antenna 5 are connected.
[0009]
[Problems to be solved by the invention]
The front-end modules shown in FIGS. 4A and 5 are separately operated in three bands having different frequencies such as GSM (900 MHz), DCS (1800 MHz), and PCS (1900 MHz) triple-band mobile phones in Europe. It cannot be applied to a phone that can be used all on one terminal.
[0010]
Therefore, in order to be able to use the three frequency bands with one mobile phone, following the configuration of FIG. 4A, as shown in FIG. 4B, another receiving circuit 17 and a transmitting circuit are provided. It is conceivable that an antenna switch 15 is added to 18, a low-pass filter 16 is provided corresponding to the transmission circuit 18, and a branching circuit 6 A composed of a triplexer is provided instead of the diplexer.
[0011]
However, when such a triple-band front-end module is constituted by a ceramic multilayer substrate, it is necessary to provide more circuit elements in the ceramic multilayer substrate, and the ceramic multilayer substrate is further complicated and reduced in size. It becomes difficult.
[0012]
In view of the problems of the prior art, the present invention can reduce the number of circuit elements when a single mobile phone is used for three communication systems, and can be reduced in size. The purpose is to provide modules.
[0013]
[Means for Solving the Problems]
The front end module for a triple band mobile phone according to claim 1 is:
A demultiplexing circuit comprising a plurality of notch circuits connected to the antenna;
An antenna switch for switching and connecting the transmission circuit and the reception circuit to the corresponding notch circuit;
A filter provided between the transmission circuit and the antenna switch for removing harmonics generated in the transmission circuit ;
A module constituting the front end of a transmission / reception circuit having three transmission / reception functions with different communication methods,
Of the three communication systems, the two communication systems that are used on the high frequency band side and that are adjacent to each other in the frequency band share one notch circuit, and an antenna switch that is connected to the dual notch circuit, The transmitter / receiver circuit used for one communication method is also used.
The notch circuit shared by the two communication methods is configured by an LC parallel resonant circuit and an inductor connecting the LC parallel resonant circuit and the antenna switch in series.
[0014]
Thus, by using both the notch circuit and the antenna switch, it is possible to reduce circuit elements and downsize the module.
[0015]
The triple-band mobile phone front-end module according to claim 2 is characterized in that in claim 1,
A diode is used as the switching means, a low-pass filter is used as the filter, and a module integrated with a ceramic multilayer substrate is used.
[0016]
Thus, by mounting the front end module on one ceramic multilayer substrate, the front end module can be easily mounted.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing an embodiment of a front end module according to the present invention. In FIG. 1, reference numeral 25 denotes a front end module. Reference numerals 1 and 2 denote a low frequency band side receiving circuit and a transmitting circuit, respectively, which are used for the GSM (900 MHz) system, for example. Reference numerals 3 and 17 denote high frequency band receiving circuits, respectively. One high frequency band receiving circuit 3 is used for the DCS (1800 MHz) system, for example, and the other high frequency band receiving circuit 17 is for example the PCS (1900 MHz). It is used for the system. Reference numeral 23 denotes a transmission circuit commonly used for two communication systems, for example, the DCS and PCS, in which two adjacent frequency bands are used.
[0018]
The front end module 25 is generated by a diplexer 60 as a demultiplexing circuit that is connected to the antenna 5 and separates into signals of a low frequency band and a high frequency band, the low frequency band antenna switch 7, and the low frequency band transmission circuit 2. A low-pass filter 10 that removes high frequencies, a low-pass filter 11A that removes harmonics generated by the transmission circuit 23 that is shared by two communication systems in the high-frequency band, and a high frequency that is shared by two transmission / reception circuits. A band antenna switch 24.
[0019]
FIG. 2 is an equivalent circuit diagram of the front end module of FIG. In FIG. 1, the low frequency band notch circuit 12 constituting the diplexer 60 includes capacitors C1 and C3 and an inductor L1. The high frequency band notch circuit 13A includes a capacitor C2 and inductors L2 and L3, and is configured to have characteristics that allow signals used for two communication systems in the high frequency band to pass. In the notch circuit 13A, the capacitor C2 and the inductor L2 constitute an LC parallel resonance circuit that cuts off a signal in a low frequency band. The inductor L3 connects the LC parallel resonant circuit and the antenna switch 24 in series.
[0020]
T11 is a connection terminal connected to the low frequency band transmission circuit 2, and corresponds to the terminal TX1 in FIG. The harmonic removal low pass filter 10 includes capacitors C4 to C6 and an inductor L4. T7 is a ground terminal connected to the receiving circuit 1, and corresponds to the terminal RX1 in FIG. The low-frequency band antenna switch 7 is inserted between the notch circuit 12 and the low-pass filter 10, and a bias terminal T10 for applying a switching bias voltage, capacitors C7 to C10, inductors L5 and L6, a resistor R1, It consists of diodes D1 and D2.
[0021]
T1 is a connection terminal connected to the high frequency band transmission circuit 23, and corresponds to the terminal TX2 in FIG. The low-pass filter 11A for removing harmonics includes capacitors C16 to C18 and an inductor L10, and is configured to obtain characteristics suitable for the frequency bands used for the two communication methods. T5 is a connection terminal connected to the high frequency band receiving circuit 3, and corresponds to the terminal RX2 in FIG. T3 is a connection terminal connected to the high frequency band receiving circuit 17, and corresponds to the terminal RX3 in FIG.
[0022]
The high frequency band antenna switch 24 is inserted between the notch circuit 13A and the low pass filter 11A, and applies a bias terminal T2 for applying a switching bias voltage, capacitors C11 to C15, C19 to C21, and inductors L7 to L9 and L11. , L12, resistor R2, and diodes D3 to D5.
[0023]
In this equivalent circuit, when a bias voltage is applied to the bias terminal T10 of the low frequency band antenna switch 7 to operate the diodes D1 and D2, the transmission circuit connection terminal T11 and the antenna 5 are connected, and the transmission circuit 2 Can be sent from the antenna 5. On the other hand, when the bias terminal T10 is not biased or is reversely biased, the receiving circuit connection terminal T7 and the antenna 5 are connected.
[0024]
In the high frequency band antenna switch 24, when a bias is applied to the bias terminal T2 of the high frequency band antenna switch 24 to operate the diodes D3 and D4, the transmission circuit connection terminal T1 and the antenna 5 are connected to each other, and transmission is performed. Any one of the two communication methods from the circuit 23 can be sent from the antenna 5.
[0025]
On the other hand, when the bias terminal T2 is not biased or reverse biased and the bias terminal T4 is not biased or reverse biased, the receiving circuit connection terminal T5 and the antenna 5 are connected. Then, a signal passing through the notch circuit 13 </ b> A from the antenna 5 is input to the receiving circuit 3.
[0026]
When the bias terminal T2 is not biased or reverse biased and the bias terminal T4 is biased, the receiving circuit connection terminal T3 and the antenna 5 are connected to each other. A signal passing through 13A is input to the receiving circuit 17.
[0027]
As described above, the notch circuit 13A is also used for two communication methods in which the frequency bands to be used are close to each other, and the low-pass filter 11A and a part of the antenna switch 24 are also used by the transmission circuit 23 used for the two communication methods. As a result, the configuration of the front end module related to the branching circuit 60 and the antenna switch 24 is simplified, the number of circuit elements is reduced, and the size can be reduced.
[0028]
Note that the transmission circuit 23 is also used for two communication systems, and the reception circuits 3 and 17 are configured separately. This is because the transmission circuit 23 can also be used for circuit operation control.
[0029]
3A is a side view of a substrate showing an example in which the front end module of the present invention is integrally formed as a ceramic multilayer substrate, FIG. 3B is a plan view thereof, and FIG. 3C is an end view thereof. It is. In these figures, reference numeral 30 denotes capacitors C1 to C21 and inductors L1 to L12 formed therein by a sheet lamination method or a screen printing method, and the terminals T1 to T12 are provided on side surfaces and end surfaces. Reference numeral 31 denotes a shield cover made of a conductive material such as a metal that covers the upper surface of the substrate 30 and also serves to be sucked by a suction nozzle of a device for mounting on a motherboard. As shown in FIG. 2, the end of the shield cover 31 is electrically connected and fixed to T6 and T12 serving as ground terminals. The shield cover 31 is provided with holes and marks 31a indicating the direction of the module. On the surface of the substrate 30, the diode 32 indicated by the above D1 to D5 is mounted. The resistors R1 and R2 are formed on the surface portion of the substrate 30.
[0030]
The size of the front end module is, for example, a length in the left-right direction of FIG. 3A of 6.5 mm, a width in the left-right direction of FIG. 3C of 4.8 mm, and a height including the shield cover 31. 1.8 mm. In this way, even with the three communication systems, it is possible to reduce the size by combining the notch circuit and the antenna switch to the transmission circuit of the two communication systems that are close to the frequency band to be used. Mounting as a surface mount component facilitates mounting.
[0031]
【The invention's effect】
According to the first aspect, since the notch circuit and the antenna switch to the transmission circuit are shared by the two communication methods, circuit elements can be reduced and the module can be downsized.
[0032]
According to the second aspect, since the front end module is housed in one ceramic multilayer substrate, the front end module can be easily mounted.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a front end module according to the present invention.
FIG. 2 is an equivalent circuit diagram showing an embodiment of a front end module according to the present invention.
3A is a side view showing an appearance of an embodiment of a front end module according to the present invention, FIG. 3B is a plan view thereof, and FIG. 3C is an end view thereof.
4A is a block diagram showing a conventional front-end module of a dual-band mobile phone, and FIG. 4B is a block diagram showing a configuration example of a triple-band mobile phone.
FIG. 5 is an equivalent circuit diagram of the front end module of FIG.
[Explanation of symbols]
1: Low frequency band receiving circuit, 2: Low frequency band transmitting circuit, 3, 17: High frequency band receiving circuit, 5: Antenna, 7: Low frequency band antenna switch, 10: Low frequency band low pass filter, 11A: High frequency Band low pass filter, 12, 13A: notch circuit, 23: high frequency band transmission circuit, 24: high frequency band antenna switch, 25: front end module, 30: multilayer substrate, 31: shield cover, 60: diplexer (demultiplexing circuit) ), 32: Diode

Claims (2)

A demultiplexing circuit comprising a plurality of notch circuits connected to the antenna;
An antenna switch for switching and connecting the transmission circuit and the reception circuit to the corresponding notch circuit;
A filter provided between the transmission circuit and the antenna switch for removing harmonics generated in the transmission circuit ;
A module constituting the front end of a transmission / reception circuit having three transmission / reception functions with different communication methods,
Of the three communication systems, the two communication systems that are used on the high frequency band side and that are adjacent to each other in the frequency band share one notch circuit, and an antenna switch that is connected to the dual notch circuit, The transmitter / receiver circuit used for one communication method is also used.
A triple-band mobile phone characterized in that the notch circuit shared by the two communication methods comprises an LC parallel resonant circuit and an inductor that connects the LC parallel resonant circuit and the antenna switch in series. Front end module. In claim 1,
A front end module for a triple-band mobile phone, wherein a diode is used as the switching means, a low-pass filter is used as the filter, and the module is integrated with a ceramic multilayer substrate.

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