KR20070051108A - Communication module of mobile communication terminal - Google Patents

Abstract

The present invention includes a front end module including a switching element, a plurality of SAW filters connected to the switching element, and a plurality of matching elements each connected to the plurality of SAW filters; A correction unit connected to the front end module to correct a signal according to a correction signal; A transmitter including an RF receiver configured to receive and process a signal output from the correction unit; A baseband processor converting an output signal of the transmitter into a baseband signal; And a digital signal processor (DSP) connected to the baseband processor to compare the voltage of the baseband signal with a predetermined reference voltage to transfer the correction signal to the correction unit. will be.

Communication Modules, Temperature Compensation, SAW Filters

Description

Communication module of mobile communication terminal

Figure 1a is a diagram showing the configuration of a conventional GSM triple band front end module.

Figure 1b is a graph showing the characteristics according to the temperature of a conventional GSM triple band front end module.

2 illustrates a communication module of a mobile communication terminal according to the present invention.

3 is a graph showing characteristics of a communication module of a mobile communication terminal according to the present invention;

* Explanation of symbols for main parts of drawings *

20: front end module 21: antenna

22: switching element 23: SAW filter stage

24: first matching element 25: second matching element

30: compensator 40: transmitter

41: RF receiver 42: RF transmitter

50: baseband processor 60: DSP

The present invention relates to a communication module of a mobile communication terminal, and more particularly, to a communication module of a mobile communication terminal having a temperature compensation function for a reception band of a front end module.

In general, in a cellular or PCS cellular phone or other wireless communication system, the front end module is located at the front of the system or device to receive input from the outside, and connects to an antenna (ANT) at approximately 824-894 MHz. A diplexer for discriminating a cellular band or a PCS band of approximately 1750-1910 MHz, and transmitting the cellular band of approximately 824-849 MHz in a transmission (TX) band and approximately 869-894 MHz DML reception (RX). And a duplexer for dividing the PCS band into a transmission (TX) band and a reception (TX) band. Here, the Korean PCS (K-PCS) band includes a transmission band of 1750 MHz to 1780 MHz and a reception band of 1840 MHz-1870 MHz, and the US PCS (US-PCS) band includes a transmission band of 1850 MHz to 1910 MHz and a 1930 MHz to 1990 MHz band. It includes the reception band of.

1 is a diagram illustrating a configuration of a general triple band front end module.

As shown in FIG. 1, a general GSM triple band front end module 10 includes a first low pass filter (LPA) 13a for removing high frequency noise of a signal transmitted from a DCS / PCS transmitter Tx, and a GSM transmitter. A second LPF 13b for removing high frequency noise of a signal transmitted from Tx), an SP3T switch 15 for changing a transmission path and a reception path of the DCS / PCS / GSM signal, and a transmission from the DCS / PCS / GSM transmitter A high frequency band corresponding to a frequency band of each system among the signals transmitted from the antenna 16 and the antenna 16 for transmitting the signal to the DCS / PCS / GSM receiving end separated and separated by the SP3T switch 15. A desired multiplexer at the GSM receiver (Rx) in the frequency band separated by a low frequency band by the diplexer 14, which determines which side to separate by DCS / PCS) and a low frequency band (GSM). Frequency bands in the range (925-960) A first band pass filter (11a) that passes only a signal of MHz (MHz) and removes signals outside this range, and the PCS band and the DCS band, which are similar frequencies in the frequency band separated by the high frequency band by the diplexer 14. The first phase shifter 12a, the second phase shifter 12b, and the PCS receiver Rx, which respectively branch the signals, pass only signals of a desired frequency band (1930 to 1990 MHz) and remove signals outside the range. The second BPF 11b, and the third BPF 11c passing only a signal of a frequency band 1805 to 1880 MHz of a desired predetermined range and removing a signal outside this range are provided by the DCS receiving end Rx.

In addition, a power supply device Vc2 for applying a voltage to the SP3T switch 15 is included.

In particular, when the common triple band front end module 10 shares a high frequency signal (DCS / PCS) of a plurality of frequency bands, a band pass filter (BPF) of a similar frequency band is used by using a phase shifter. It has a structure to branch off. That is, it consists of a structure that receives signals by splitting a similar frequency band of DCS having a frequency band of 1805 ~ 1880 MHz and PCS having a frequency band of 1930 ~ 1990MHz by using a phase shifter. Here, the phase shift angle of the phase circuit is made such that the input impedance of the pass band of the filter in the other high frequency circuit is made large so as to have a structure that eliminates leakage of each frequency component.

Further, the first phase shifter P. S1 12a is constituted by a transmission line on a line in which the impedance of the input side is almost open at the pass band frequency of the BPF2 11b, and the second phase shifter P. S1: 12a. S2: 12b is composed of a transmission line on a line where the impedance on the input side is almost open at the pass band frequency of the BPF3 11c.

In addition, a diplexer 14 for determining whether to connect a signal to a low frequency side or a high frequency side in response to a frequency band of each system, and a high frequency switch unit 15 for changing a signal path of a reception path and a transmission path are provided. The included module is used.

Here, as illustrated in FIG. 1B, each filter of the triple band front end module 10 outputs an abnormal signal according to a change in ambient temperature, that is, when the ambient temperature rises, the output waveform is the band limit line A of the SAW filter. If you move to a dashed line over (A ') and the ambient temperature drops, the output waveform moves to a broken line, which can cause malfunctions by loss of characteristics in cellular or PCS mobile phones or other wireless communication systems due to such anomalies. have.

Therefore, there is a need for a device for compensating for an abnormal signal output according to a change in ambient temperature for each filter of the triple band front end module.

An object of the present invention is to implement a communication module of a mobile communication terminal that compensates for an error in a reception band such as an abnormal signal output from an RF SAW filter according to a change in ambient temperature.

The present invention for achieving the above object comprises a front end module comprising a switching element, a plurality of SAW filters connected to the switching element, and a plurality of matching elements respectively connected to the plurality of SAW filters; A correction unit connected to the front end module to correct a signal according to a correction signal; A transmitter including an RF receiver configured to receive and process a signal output from the correction unit; A baseband processor converting an output signal of the transmitter into a baseband signal; And a digital signal processor (DSP) connected to the baseband processor to compare the voltage of the baseband signal with a predetermined reference voltage and transmit the correction signal to the correction unit. It relates to a communication module.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. The communication module of the mobile communication terminal according to the present invention will be described taking a communication module including a GSM triple band front end module as an example.

2 is a diagram illustrating a communication module of a mobile communication terminal according to the present invention. The communication module of the mobile communication terminal according to the present invention includes a front end module 20, a correction unit 30, a transmitter 40, and a baseband. And a processing unit 50 and a DSP (Digital Signal Processor) 60.

The front end module 20 includes a switching element 22 connected to the antenna 21, a SAW filter stage 23 including SAW filters, for example, five SAW filters respectively connected to the switching element 22, and a SAW filter stage 23. And a first matching element 24 and a second matching element 25 connected to each SAW filter (not shown).

The signal output through the SAW filter stage 23 is input to the first matching element 24 and the second matching element 25, and is output by the first matching element 24 and the second matching element 25. The impedance of the signal is matched with the adjusted signal (hereinafter referred to as a matching signal) and input to the corrector 30. Here, the first matching element 24 and the second matching element 25 may be an inductor.

The correction unit 30 is disposed between the front end module 20 and the transmitter 40 and adjusts the voltage of the matched signal changed according to temperature change according to a correction signal transmitted from the DSP 60. It may be a voltage control capacitor or a transistor such as a MOSFET and the like, and adjusts the voltage of the matched signal to output to the transmitter 40.

The transmitter 40 includes an RF receiving end 41 and an RF transmitting end 42. The RF receiving end 41 receives and processes the matching signal from the compensator 30, and the RF transmitting end 42 receives the baseband part 50. The data transmitted to the outside is transmitted as a radio signal.

The baseband processor 50 converts the baseband signal transmitted from the inside of the wireless communication system into a high frequency signal and transmits it to the outside, and transmits the high frequency signal received through the RF receiver 41 to a base such as a DC voltage. The signal is converted into a band signal and transmitted to the DSP 60.

The DSP 60 receives the baseband signal through the baseband processor 50 and compares the input baseband signal, for example, a DC voltage, with a predetermined reference voltage to generate a power control signal. In detail, when the DC voltage is higher than the reference voltage, the DSP 60 transmits a control signal to reduce the voltage to the correction unit 30. On the contrary, when the DC voltage is lower than the reference voltage, the DSP 60 corrects the correction unit. The control signal 30 increases the voltage.

The communication module having such a configuration is predetermined from the DSP 60 to the correction unit 30 in order to compensate for the loss of the reception band output from the SAW filter stage 23 according to the change of the ambient temperature in the temperature compensation circuit of the front end module. The correction signal is transmitted, and the correction unit 30 adds or subtracts a predetermined voltage to the match signal passed through the first matching element 24 and the second matching element 25.

Therefore, when the ambient temperature rises as shown in FIG. 3 and is output as a dotted line exceeding the band limit line A-A 'of the SAW filter, a predetermined power control signal is transmitted from the DSP 60 to the correction unit 30. The predetermined voltage is transmitted to the corrector 30 according to the power control signal, and the capacitance of the corrector 30 is adjusted by the applied voltage. Therefore, the dotted line shown in FIG. 3 moves in a straight line so that insertion loss does not occur.

On the contrary, as shown in FIG. 3, when the ambient temperature drops and outputs from the SAW filter together with the broken line, a predetermined correction signal is transmitted from the DSP 60 to the compensator 30 to move in a straight line at the broken line. .

According to the present invention by providing a temperature compensation circuit of the front end module to prevent and compensate the insertion loss of the signal output from the SAW filter to be transmitted to the RF receiver 41 of the transmitter 40 to improve the reception sensitivity.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiments are for the purpose of description and not of limitation.

In addition, those skilled in the art will understand that various implementations are possible within the scope of the technical idea of the present invention.

As described above, the present invention implements a communication module of the mobile communication terminal that compensates for the loss of the band output from the RF SAW filter, thereby preventing the loss of characteristics of the front end module due to the change of ambient temperature, thereby improving the reception sensitivity. .

Claims (4)

A front end module including a switching element, a plurality of SAW filters connected to the switching element, and a plurality of matching elements respectively connected to the plurality of SAW filters; A correction unit connected to the front end module to correct a signal according to a correction signal; A transmitter including an RF receiver configured to receive and process a signal output from the correction unit; A baseband processor converting an output signal of the transmitter into a baseband signal; And And a digital signal processor (DSP) connected to the baseband processor to compare the voltage of the baseband signal with a predetermined reference voltage and transmit the correction signal to the correction unit. The method of claim 1, The correction unit is a communication module of the mobile communication terminal for applying a voltage to the output signal of the front end module in accordance with the correction signal received from the DSP. The method of claim 1, The correction unit is a communication module of the mobile communication terminal, characterized in that the voltage control capacitor or MOSFET (Metal-Oxide Semiconductor Field Effect Transistor). The method of claim 1, If the voltage of the baseband signal is higher than the predetermined reference voltage, the DSP transmits a correction signal to reduce the voltage to the correction unit, And when the voltage of the baseband signal is lower than the predetermined reference voltage, the DSP transmits a correction signal of increasing the voltage to the correction unit.

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