KR20080006414A - Front end module and communication system - Google Patents

Abstract

A front end module and a communication system are provided to include a switch element in the front end module as excluding a power amplification module, and to improve a terminal structure for connection configuration with the power amplification module, thereby improving a transceiving functionality by obtaining sufficient isolation between components as minimizing size. A receiver(320) processes an RF(Radio Frequency) receiving signal. A transmitter(330) processes an RF transmission signal, and has terminals connected with an externally separated power amplification module. A transceiving separator separates the RF transmission/receiving signals to deliver the separated signals. A reference switch unit(360) has a reference voltage terminal. A load switch unit(350) has a power apply terminal.

Description

Front End Module and Communication System

1 is a circuit block diagram schematically showing the components of a typical CDMA front end module.

2 is a top view illustrating a case where a general CDMA front end module is implemented on a substrate.

3 is a block diagram schematically illustrating components of a communication system according to an embodiment of the present invention;

4 is a block diagram schematically illustrating components of a front end module according to an embodiment of the present invention;

5 is a block diagram showing a terminal configuration of a load switch provided in the front end module according to an embodiment of the present invention.

6 is a block diagram illustrating a terminal configuration of a reference switch provided in the front end module according to the embodiment of the present invention.

7 is a top view schematically illustrating a form in which the front end module is mounted on a substrate according to an embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

1000: communication system 100: antenna

200: switching circuit 300: front end module

310: duplexer 320: receiver

322: RF receiver 324: IF receiver

326: receiving processor 330: transmitting unit

332: IF transmitter 334: transmission processor

340: Transmit bandpass filter (TxBPF) 350: Load switch

360: reference switch 400: baseband processor

500: power amplifier module

The present invention relates to a communication system comprising a front end module and a front end module.

A front end module (FEM) is a transmitting / receiving device that controls radio signals used on a mobile communication terminal, and is a complex component in which various electronic components are serially implemented on one substrate to minimize integration space. Means.

For example, a front end module that processes a code division multiple access (CDMA) signal will be described as follows.

1 is a circuit block diagram schematically showing the components of a typical CDMA front end module.

Referring to FIG. 1, a general CDMA front end module includes a transceiver 30, a transmitter 50, a receiver 40, and a GPS (Global Position System) unit 60. ) Is implemented as a duplexer, and the transmission unit 50 includes a transmission processing module (Tx BBA or RF Transmitter) 56, a transmission filter 54 and a power amplifier module (PAM) 52. In addition, the receiver 40 includes a low noise amplifier (LNA) 42, a reception filter 44, and a reception processing module (Rx BBA or RF Receiver) 46, and the GPS unit 60. ) Is composed of a GPS filter 62 and a GPS processing module 64.

The duplexer 30 connected to the switching circuit 20 and the antenna 10 separates the transmitted / received signals and transmits them to the antenna 10 or the receiver 40. When the GPS signal and the CDMA signal are received through the antenna 10, The switching circuit 20 separates the two signals.

In addition, the reception processing module 46 and the transmission processing module 56 are connected to the baseband processing unit 70, the baseband processing unit 70 generates multimedia data by analyzing digital signals, and performs operations of each circuit unit. To control.

The transmission processing module 56 and the reception processing module 46 modulate / demodulate an intermediate frequency signal or a digital signal and process A / D or D / A conversion.

The transmission filter 54 or the reception filter 44 filters the transmission band frequency signal or the reception band frequency signal, and the power amplifier 52 and the low noise amplifier 42 each process the transmitted signal as a transmission signal or a reception signal. Amplify the signal to a predetermined size so that it can

The GPS unit 60 filters the GPS signal to attenuate the noise component, extracts only the corresponding band frequency, generates the intermediate frequency, and transmits the intermediate frequency to the baseband processor 70.

2 is a top view illustrating a case where a general CDMA front end module is implemented on a substrate.

According to FIG. 2, the CDMA front end module described with reference to FIG. 1 is mounted on a substrate. The antenna 10, the switch circuit 20, and the GPS unit 60 are mounted on the substrate, and the transmitter 50 is provided. The receiver 40 and the transceiver 30 separate each block and are mounted in the area below.

The baseband processor 70 is mounted in an area under the transmitter 50, the receiver 40, and the transceiver 30.

Since the front end module made of various electronic components simultaneously processes the transmission signal and the reception signal, the front end module is exposed to severe radio wave interference and generates the effect of signal crosstalk due to the generation of high heat.

In general, such electromagnetic interference is called EMI (Electromanetic Emission / Interface), the electromagnetic signal unnecessarily radiated (RE) or conducted (CE) conducted from the electronic device, and the thermal conduction phenomenon of the adjacent electronic device It impairs the function, worsens the circuit function and causes the malfunction of the equipment.

Therefore, in the front end module, minimizing thermal and electrical interference is an important factor in maintaining communication quality, and circuit layout design considering isolation between electronic devices is a very important factor in improving transmission and reception functions. have. In particular, since interference and thermal conduction occur most frequently in the power amplification module, the isolation problem between the power amplification module and other components should be considered as the top priority in the circuit layout design.

According to the structure of a general front end module, since the receiver 40, the transmitter 50, and the transceiver separation unit 30 are not formed as a single module and are mounted together with other components on one substrate, the influence of the radio wave cannot be minimized. The mounting / bonding / molding process of the device is complicated and time consuming.

In addition, according to the structure of the conventional front end module, there are many restrictions to minimize the size.

The present invention provides a front end module capable of minimizing electrical and thermal interference by increasing isolation between components through an optimal layout design.

The present invention provides a communication system using a front end module in which the arrangement of devices and the connection configuration through terminals are improved.

The front end module according to the present invention includes a receiver for processing an RF received signal; A transmission unit for processing an RF transmission signal and having a terminal connected to a power amplifier module separated to the outside; And a transmission / reception section for separating and transmitting the RF transmission / reception signal to form a unit module.

In addition, the terminal provided in the front end module according to the present invention includes a reference voltage terminal (PA-Vref); Power supply terminal PA_Vcc; An output terminal for transmitting a signal to the power amplifier module; And one or more terminals among input terminals receiving signals from the power amplifier module.

Communication system according to the present invention includes the front end module; And a power amplifier module connected to the front end module through a terminal.

Hereinafter, a communication system and a front end module according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram schematically showing the components of a communication system according to an embodiment of the present invention, Figure 4 is a block diagram schematically showing the components of a front end module according to an embodiment of the present invention.

3 and 4, the communication system 1000 according to the embodiment of the present invention is largely an antenna 100, a switching circuit 200, a GPS filter 210, a front end module 300, a baseband processor ( 400) and a power amplification module 500. The front end module 300 includes a duplexer 310, a transmitter 330, a receiver 320, a load switch 350 and a reference switch 360. It is made to include.

In addition, the receiver 320 is an RF receiver 322 consisting of a low noise amplifier (LNA) 322a, a reception bandpass filter (Rx BPF) 322b, a first mixer 324a, and a first phase synchronization circuit. 324b, an IF receiving end 324 composed of the first IF filter 324c, and a receiving processor 326.

In addition, the transmitter 330 is composed of a second mixer 332a, a second phase synchronizer circuit 332b, a second IF filter 332c, and an IF transmitter 332, a transmitter processor 334, and a transmission bandpass filter (Tx). BPF) 340.

The duplexer 310 is connected to the antenna 100 through a switching circuit 200, and the switching circuit 200 is connected to a reception processor 326 through a GPS filter 210. 326 and the transmission processor 334 are connected to the baseband processor 400, respectively.

The front end module 300 has at least four terminals (a, b, c, d) connected to the power amplification module 500, the external through the terminals (a, b, c, d) Sends and receives a signal with the power amplification module 500 and transmits a control signal to the power amplification module 500.

The terminals a, b, c, and d will be described in detail with reference to FIGS. 5 to 6.

The components of the communication system 1000 having such a connection configuration will be briefly described as follows.

The antenna 100 receives the GPS signal and the CDMA signal and transmits the same to the switching circuit 200. The switching circuit 200 separates the GPS signal and the CDMA signal and transmits the GPS signal to the GPS filter 210. The signal is passed to the duplexer 310.

The switching circuit 200 may be implemented as, for example, a diplexer or a single pole double throw (SPDT) switch. The diplexer is a high pass passive device (HPF) configured with a high performance passive element (IPD). High pass filter (LPF) and low pass filter (LPF), the HPF passes a relatively high-band CDMA signal from the signal received from the antenna 100 to the duplexer 310, LPF The low-band GPS signal is filtered and transmitted to the GPS filter 210.

In addition, the SPDT switch is an IC (Integrated Circuit) switch, which operates from DC to about 3 GHz with two positive control voltages, and has a very low control voltage and can be opened and closed at 2.4V.

The duplexer 310 separates the CDMA signal into a transmission signal and a reception signal and transmits the CDMA signal to the antenna 100 or the receiver 320, respectively.

The low noise amplifier 322a amplifies the received signal by suppressing a noise component, and the reception bandpass filter 322b filters the mixed signals generated during the amplification process and passes only the received signal of the corresponding band.

The first phase synchronizer circuit 324b includes a TCXO (Temperature Compensated Crystal Oscillator), a comparator (Phase detector), a pulse / voltage converter, a VCO, and a feedback circuit (divider). The VCO provides a stable and variable frequency source as needed.

The first mixer 324a mixes the RF reception signal transmitted from the reception bandpass filter 322b with the frequency source signal transmitted from the first phase synchronization circuit 324b, thereby receiving an intermediate frequency (IF) received signal. To create.

The first IF filter 324c filters the mixed noise component signals in the mixing process and transfers the filtered signals to the reception processor 326.

The reception processor (commonly referred to as "RF BBA" or "RF receiver") 326 includes a modulator, a low pass filter (LPF), a D / A converter, and the like to code / receive a received signal. Filter and convert to digital signal.

In particular, the reception processor 326 implemented as a single chip includes a GPS signal processing unit (Asynchronous GPS) therein, and the GPS signal processing unit demodulates the GPS signal transmitted from the GPS filter 210 and converts it into digital data. Transfer to the baseband processor 400.

The baseband processor (commonly referred to as "BBA") 400 includes a CPU, a CDMA digital modulator, a channel encoder / decoder, and the like, and encodes / decodes a CDMA signal to process and display the multimedia data as a multimedia data. A user interface is provided by controlling input / output devices such as a device and a keypad.

In addition, when the baseband processor 400 modulates the demodulated transmit / receive signal, the baseband processor 400 senses the signal strength to generate a gain control signal, and transmits the gain control signal to the low noise amplifier 322a or the power amplifier module 500. Adjust the signal strength.

Next, referring to the transmitter 330, the transmitter 334 includes a demodulator, a low pass filter, an A / D converter, and the like to digitize the transmitted signal transmitted from the baseband processor 400. Decode / filter and convert to analog signals.

The second IF filter 332c filters only signals of a corresponding band among the analogized signals input from the transmission processor 334, and the second mixer 332a filters the baseband signal transmitted from the second IF filter 332c. It is mixed with the frequency source signal transmitted from the second phase synchronization circuit 332b to generate an IF transmission signal.

The second phase synchronizer circuit 332b has a configuration similar to that of the first phase synchronizer circuit 324b described above, and provides a frequency source signal for generating a transmission band frequency.

The transmission bandpass filter 340 filters the received signal as an RF signal and transfers the filtered signal to the power amplification module 500 located outside the front end module.

The front end module 300 according to the present invention having such a configuration has a power amplification module 500 that causes the most radio wave interference unlike the prior art, and includes a transmitter 330, a receiver 320, and a duplexer 310. ) Into a single module.

Hereinafter, the connection relationship and operation of the reference switch 360, the load switch 350, and the power amplifier module 500 included in the front end module 300 will be described with reference to the accompanying drawings.

5 is a block diagram illustrating a terminal configuration of the load switch 350 provided in the front end module 300 according to the embodiment of the present invention.

When the filtered signal is transmitted from the transmission bandpass filter 340, the power amplification module 500 amplifies the transmitted signal to a sufficient size so that the transmitted signal can be emitted through the antenna 100. The load switch 350, the reference switch 360, the duplexer 310, and the transmission bandpass filter 340 of the end module 300 are connected to each other.

Referring to FIG. 5, the load switch 350 includes a "Vbatt" terminal, a "PA_Vcc" terminal, and an "LS_out" terminal. The power amplifier module 512 includes a "PA_Vcc" terminal, a "PA_Vcon" terminal, and a "PA_Vref" terminal. Terminals, " P_in " terminals, and " P_out " terminals.

The load switch 300 is connected to the power supply unit (battery circuit) through the "Vbatt" terminal and receives power.

In addition, the load switch 350 is connected to the baseband processor 400 through the "PA_Vcc_on" terminal, and receives a control signal from the baseband processor 400 determines whether the control signal is a high mode or a low mode. .

The load switch 350 supplies power to the power amplifier module 500 when the control signal is in the high mode, and does not supply power to the power amplifier module 500 when the control signal is in the low mode.

The load switch 350 outputs the power applied from the power supply unit through the "LS_out" terminal, and the "PA_Vcc" terminal of the power amplification module 500 is connected to the "LS_out" terminal of the load switch to receive the applied power. .

Such a load switch 350 may be provided as a separate switch element, or may be implemented as a switching circuit using a resistor, a switching transistor, a capacitor, and a diode.

6 is a block diagram illustrating a terminal configuration of the reference switch 360 provided in the front end module according to the embodiment of the present invention.

Referring to FIG. 6, the reference switch 360 has a circuit including two switching elements therein, and a transistor semiconductor element such as a bipolar junction transistor (BJT) may be used as the switching element. In the embodiment of the present invention, the switching element is assumed to be provided as a BJT (transistor).

The two transistors provide a reference voltage for the amplification operation of the power amplification module 500. The two transistors form a circuit with four resistors R1, R2, R3, and R4 to form a total of five terminals.

At this time, the collector of the first transistor Q1, which is npn BJT, becomes the ground terminal GND, and the emitter becomes a floating (usually, it is not electrically connected and used when fixing the device to the substrate or the housing).

The base terminal of the first transistor Q1 includes a fourth resistor R4 to enable the enable signal terminals V_en and en; and the ground terminal GND and the enable signal terminal V_en have a second resistor. Connected via (R2).

The collector of the second transistor Q2, which is pnp BJT, becomes the reference voltage generation signal terminal (V_reg, reg; regulator), and the base of the second transistor Q2 is connected to the collector through the third resistor R3. The first resistor R1 is connected to the emitter of the first transistor Q1. The emitter of the second transistor Q2 becomes the reference voltage output terminal V_ref, ref; reference.

When a voltage of about 2.9 V is applied to the reference voltage generation signal terminal V_reg and an amplification control signal (enable signal) is input from the baseband processor 400 to the enable signal terminal V_en, the first transistor Q1 is applied. The potential of the collector becomes low.

When the collector potential of the first transistor Q1 is lowered, a voltage of a predetermined value is applied to the first resistor R1 and the third resistor R3, and the second transistor Q2 is operated to turn on the collector, That is, a voltage may be applied to the reference voltage generation signal terminal V_reg.

As voltage is applied to the reference voltage generation signal terminal V_reg, current flows in the internal circuit, and the reference voltage for processing the corresponding band frequency is finally transmitted to the emitter of the second transistor Q2, that is, the reference voltage output terminal Vref. Is output.

The power amplifier module 500 may include an input matching circuit, a driver amplifier (DA), an intermediate matching circuit, a power amplifier (PA), an output matching circuit, and a bias circuit (components of the power amplifier module). And not shown, and has five terminals as described above.

First, the "PA_Vcc" terminal is connected to the power amplifier module 500 by two lines, and transmits the first power source Vcc1 and the second power source Vcc2 through each line.

At this time, 3.8V to 4.2V power is supplied to the first power supply and the second power supply.

In addition, the power amplifier module 500 is connected to the transmission band pass filter 340 through the "P_in" terminal, and amplifies the RF signal input through the "P_in" terminal.

The power amplification module 500 is connected to the duplexer 310 (see FIG. 4) through the "P_out" terminal, and outputs the amplified RF signal to the duplexer 310 through the "P_out" terminal.

The “PA_Vcon” terminal is connected to the enable signal terminal of the reference switch 360 to receive an enable signal. An operation state of the power amplification module 500 is determined according to the enable signal.

In addition, the "PA_Vcon" terminal may be connected to a bias transistor located inside the power amplification module 500, and the base terminal current of the amplifying transistor may be controlled by transferring a high or low voltage.

The "PA_Vref" terminal is connected to the reference voltage output terminal of the reference switch 360 to receive a reference voltage, and may be connected to a bias transistor provided in the power amplifier module 500. The "PA_Vref" terminal may be connected to the active region. It receives a certain amount of current and transfers it to the base end of the amplifying transistor provided in the power amplification module 500.

7 is a top view schematically illustrating a form in which the front end module 300 according to an embodiment of the present invention is mounted on a substrate.

As shown in FIG. 7, the front end module 300 includes a transmitter 330 and a receiver 320 by an isolation wall G formed with a duplexer 310 mounted on an upper end of a central portion of a substrate. Are separated and mounted on both sides.

That is, the circuit arrangement design considering the isolation between electronic devices is a very important factor in improving the transmission / reception function. For example, the isolation between the input / output terminal of the reception bandpass filter 322b and the power amplification module 500 is a circuit. It is a very important factor to maintain the stability of the.

At this time, the required isolation value should be at least 5dB at least 79dB from the output of the reception bandpass filter 322b, and should be at least 64dB at least 60dB from the input of the reception bandpass filter 322b. .

However, in the front end module 300 according to the present invention, the power amplification module 500 is provided by leaving the power amplification module 500 externally, and connecting the control switch-load switch 350 and the reference switch 360 to the inside. Minimize the effect of radio interference from

According to FIG. 7, components of the receiver 320 are mounted on the right side of the isolation wall G, and components of the transmitter 330 are mounted on the left side of the isolation wall G. The transmission processor 334 and the IF are mounted. The transmitter 332 is implemented as a single chip, and the transmission band pass filter (Tx BPF) 340, the load switch 350, and the reference switch 360 may be mounted as separate elements.

Therefore, interference propagation is generated from the power amplification module 500 connected to the load switch 350 and the reference switch 360, and is blocked by the partition wall G even if it affects the inside of the front end module 300. It has a structure, and the reception bandpass filter 322b is disposed adjacent to the end of the right side of the substrate to maximize isolation.

Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the present invention, the switch element is included in the front end module, the power amplifier module is excluded, and the terminal structure is improved for the connection configuration with the power amplifier module. Can provide improved front end modules.

Claims (7)

A receiver for processing an RF received signal; A transmitter for processing an RF transmission signal and having a terminal connected to an externally separated power amplifier module; And Front-end module forming a unit module including a transmission and reception separation unit for separating and transmitting the RF transmission and reception signals. The method of claim 1, wherein the terminal Reference voltage terminal PA-Vref; Power supply terminal PA_Vcc; An output terminal for transmitting a signal to the power amplifier module; And And at least one terminal among input terminals receiving a signal from the power amplification module. The method according to claim 1 or 2, A reference switch unit having a reference voltage terminal; And A front end module further comprising a load switch unit having a power supply terminal. The method of claim 4, wherein the input terminal Front end module, characterized in that connected to the transceiver. The method of claim 1, wherein the transmitting unit, the receiving unit and the transmission and reception separation unit A front end module, characterized in that each mounted on the substrate area separated by the partition wall. The method of claim 5, And a reference switch unit and a load switch unit mounted in the same area as the transmitter. A front end module according to any one of claims 1 to 6; And And a power amplifier module connected to the front end module through a terminal.

Images