KR100629575B1 - Radio frequency front end module - Google Patents

Abstract

RF front-end module according to the present invention includes a duplexer for filtering and selectively transmitting the signal transmitted and received through the antenna; A transmission stage for transmitting a signal of a transmission frequency band, a transmission stage comprising a power amplifier module amplifying the signal processed by the transmission filter for transmission to the duplexer and located adjacent to one end on a substrate; And a low noise amplifier module for suppressing low noise components and amplifying a signal transmitted from the duplexer, and having a receiving filter configured to pass only signals of a reception frequency band and to be adjacent to the other side of the substrate.

According to the present invention, it is possible to provide an RF front-end module with improved transmission / reception function while minimizing size by providing a circuit structure that minimizes the influence of parasitic components and an arrangement structure of circuit elements that are improved to ensure sufficient isolation between circuit elements. It has an effect.

Description

RF front end module

1 is a circuit block diagram schematically showing the components of an RF front end module used in a typical CDMA mobile communication terminal.

2 is a diagram showing a measurement form of isolation between circuit elements included in an RF front end module A used in a general CDMA mobile communication terminal.

3 is a circuit block diagram schematically showing internal components of an RF front end module according to an embodiment of the present invention;

4 is a diagram illustrating a ground pattern of a substrate on which an RF front end module according to an embodiment of the present invention is implemented.

<Explanation of symbols for main parts of drawing>

100: antenna 200: diplexer

300: GPS filter 400: RF front end module

410: duplexer 420: power amplifier module

430: low noise amplification module 440: transmission filter

450: reception filter 460: RF transmission module

470: RF receiving module 500: baseband processing unit

The present invention relates to an isolation structure of an RF front end module.

A front end module (FEM) is a transmitting / receiving device that controls radio signals used in a mobile communication terminal. A composite part in which various electronic components are serially implemented on a single board to minimize integration space. Means.

For example, a diplexer for separating a PCS (Personal Communications System) signal and a Code Division Multiple Access (CDMA) signal, a duplexer for separating transmission and reception signals, and a transmitter (Tx) filter For example, components such as a receiver (Rx) filter may be configured as a chip having a minimized size as a single module.

The mobile communication terminal includes a plurality of chip modules composed of various electronic devices including the front end module, and each module needs to be isolated from each other because it causes thermal or electrical interference.

This will be described with the front end module as an example.

1 is a circuit block diagram schematically showing the components of an RF front end module A used in a typical CDMA mobile communication terminal.

According to Figure 1, the general RF front end module (A) is largely composed of the transmitting end side and the receiving end side components, the transmission processing module 12, the transmission filter 14, the power amplifier module 16 constitutes a transmission end, The reception processing module 13, the reception filter 15, and the low noise amplification module 17 form a receiving end.

The power amplification module 16 and the low noise amplification module 17 are connected to the duplexer 19, and the duplexer 19 is connected to the GPS filter 20 and the antenna 21.

In addition, the transmission processing module 12 and the reception processing module 13 are connected to the baseband processing unit 11.

The baseband processor 11, the RF front end module A, the duplexer 19, the antenna 21, and the GPS filter 20 constitute the entire RF system 10.

The baseband processor 11 includes a phase synchronization loop for synchronizing a signal transmitted between a transmitter and a receiver, a transmitter-side digital to analog (DA) converter, and a receiver-side analog to digital (AD) converter.

As such, the RF front-end module for CDMA composed of various electronic components simultaneously processes the transmission signal and the reception signal, and thus is exposed to severe radio wave interference and generates the influence 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.

Here, CE (Conducted Emission) is electromagnetic noise mainly generated below 30 MHz, and is transmitted through a medium such as a signal line or a power line and measured in a shield can area.

On the other hand, the radiated emission (RE) is mainly electromagnetic noise generated at 30 MHz or more, and radiated into the atmosphere, and thus has a wider emission range than the CE.

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.

FIG. 2 is a diagram illustrating a measurement form of isolation between circuit elements included in an RF front end module A used in a general CDMA mobile communication terminal.

Referring to FIG. 2, the isolation between the transmission processing module 12, the transmission filter 14, the power amplifier module 16, the reception processing module 13, the reception filter 15, and the low noise amplification module 17 is measured. The figure shows the isolation value that must be secured between components in order to perform the transmission and reception function smoothly as follows.

Comparison 1 Comparison 2 Isolation figures Transmission filter (14) input Low noise amplification module (17) input 44 dB (a) Power amplifier module (16) output stage Receive filter (15) output stage 79 dB (b) Power amplifier module (16) output stage Receive filter (15) input 64 dB (c) Power amplifier module (16) output stage Low noise amplification module (17) input 70 dB (d) Receive filter (15) input Low noise amplification module (17) input 31 dB (e) Receive filter (15) output stage Low noise amplification module (17) input 51 dB (f)

In addition, the signal characteristics of each component are as follows.

Construction Signal characteristics Transmission filter (14) IL = 1.5dB, Attenuation = 40dB Power Amplifier Modules (16) Gain = 28dB, ACPR1 = 50dB, ACPR2 = 65dB Duplexer (18) Tx IL = 2dB, Tx ISO = 50dB, Rx IL = 2.5dB, Rx ISO = 55dB Low Noise Amplification Module (17) Gain = 10dB, NF = 1.2dB Receive Filter (15) IL = 2dB, Attenuation = 40dB

The isolation value shown in Table 1 is a minimum value for interlocking each component. According to Table 1, the isolation value between the power amplifier module 16 and the low noise amplifier module 17 includes a duplexer 18. 70dB or more, and the port requiring the largest isolation when viewed from the power amplification module 16 is an input / output terminal of the reception filter 15.

As such, the isolation between the input / output terminal of the receiving filter 15 and the power amplifier module 16 is the most important item in the RF front end module A. According to the measurement, the output terminal of the receiving filter 15 The isolation value required between the power amplifier and the output stage of the power amplifier module 16 is about 79 dB.

Important checks for RF performance include receiver sensitivity and STD (Single Tone Desensitization), which measures the receiver's ability to receive RF signals on a given channel when a single tone is present at a given location from the center frequency of the assigned channel. When the isolation value is obtained, the reception sensitivity of the RF front end module is -109 dBm and the STD is -105 dBm.

Accordingly, in order to maintain stable RF performance, there is a demand for improvement of an arrangement design capable of sufficiently securing the isolation between circuit elements constituting the RF front end module.

Accordingly, the present invention provides an arrangement design method that can ensure optimal isolation between circuit elements based on the measurement result and minimize the mutual influence during transmission and reception in the RF front-end module which simultaneously processes transmission and reception, and accordingly It is an object to provide an arrangement structure of circuit elements.

In order to achieve the above object, the RF front end module according to the present invention comprises a duplexer for selectively transmitting a signal transmitted and received through the antenna; A transmission stage for transmitting a signal of a transmission frequency band, a transmission stage comprising a power amplifier module amplifying the signal processed by the transmission filter for transmission to the duplexer and located adjacent to one end on a substrate; And a low noise amplifier module for suppressing low noise components and amplifying a signal transmitted from the duplexer, and having a receiving filter configured to pass only signals of a reception frequency band and to be adjacent to the other side of the substrate.

In addition, the transmitting end and the receiving end provided in the RF front end module according to the present invention is characterized in that separated by a separation wall on the substrate.

In addition, the duplexer provided in the RF front end module according to the present invention is adjacent to one end on the substrate, characterized in that located in the center of the transmitting end and the receiving end.

In addition, the transmitting end provided in the RF front end module according to the present invention is characterized in that it further comprises an RF transmitting module for controlling the gain of the baseband signal, and transmitting the transmission signal to the transmission filter.

In addition, the receiving end provided in the RF front end module according to the present invention is characterized in that it further comprises an RF receiving module for controlling and converting the gain of the RF signal transmitted from the receiving filter.

In addition, the substrate provided in the RF front end module according to the present invention has a multi-layered structure, and the ground pattern of the ground layer located below is characterized in that the transmitting, receiving and antenna side pattern portions are opened.

In addition, the RF front end module according to the present invention is characterized in that the isolation value between the output terminal of the power amplifier module and the output terminal of the receiving filter is 75dB or more.

In addition, the RF front end module according to the present invention is characterized in that the clearance value between the output terminal of the power amplifier module and the input terminal of the receiving filter is 60dB or more.

Hereinafter, an RF front end module according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The RF front end module according to an embodiment of the present invention is assumed to be a front end module for processing a CDMA signal.

3 is a circuit block diagram schematically showing internal components of an RF front end module according to an embodiment of the present invention.

Referring to FIG. 3, the RF front end module 400 according to the embodiment of the present invention includes a duplexer 410, a power amplification module 420, a transmission filter 440, an RF transmission module 460, and a low noise amplification module 430. ), A reception filter 450, an RF reception module 470, and a GPS filter 300, wherein the transmission filter 440, the power amplification module 420, and the RF transmission module 460 constitute a transmission end. The low noise amplification module 430, the receiving filter 450, and the RF receiving module 470 constitute a receiving end.

In addition, the RF transmitting module 460 and the RF receiving module 470 are connected to the baseband processor 500, the duplexer 410 is connected to the diplexer 200.

The diplexer 200 is composed of a high pass filter (HPF) and a low pass filter (LPF) composed of a high performance passive device (IPD), by applying a frequency division multiplexing scheme (multiple The entire signal (mixed frequency signal) is separated into two frequency bands in which the frequency spectrum does not overlap.

The diplexer 200 separates the CDMA band signal and the GPS band signal from the signal input from the antenna 100, and transmits the CDMA band signal to the duplexer 410, and transmits the GPS band signal to the GPS filter 300. do.

The GPS filter 300 filters a GPS signal in a band of 1570 to 1580 MHz as a band pass filter and transmits the GPS signal to the RF receiving module 470.

The duplexer 410 is a key passive component located at the very beginning of the antenna 100 together with the diplexer 200. The duplexer 410 filters the frequency and selectively transmits the CDMA signal to both bands of transmission and reception simultaneously. .

Since the duplexer 410 shares the antenna 100 and can effectively radiate radio waves without being influenced by mutual interference of transmission and reception radio waves, the reception filter 450 even when the transmission filter 440 connected to the duplexer 410 is transmitting. It also allows reception.

As described above, the receiving end includes a low noise amplification module 430, a receiving filter 450, and an RF receiving module 470. The low noise amplifying module 430 amplifies the signal to enable demodulation of the CDMA signal. In this case, the noise generated inside the amplifier is also amplified together so as to suppress the degradation of the signal-to-noise ratio.

The reception filter 450 is an Rx bandpass filter (BPF), and may be provided as, for example, an Rx SAW filter. The reception filter 450 passes only a desired frequency among signal components of various input frequency bands and attenuates signals of the remaining frequency bands.

The reception filter 450 according to the present invention processes the reception frequency of the 2.3 GHz to 2.33 GHz band of the CDMA signal.

The RF receiving module 470 synthesizes an RF signal passing through the reception filter 450 to generate an intermediate frequency signal, and controls the gain of the intermediate frequency signal to amplify it.

Meanwhile, the RF transmitting module 460 constituting the transmitting end synthesizes the baseband signal transmitted from the baseband processor 500 to generate an intermediate frequency signal, and controls and amplifies the gain of the generated intermediate frequency signal.

The transmission filter 440 is a Tx band pass filter (BPF), and may be provided as a Tx SAW filter like the reception filter 450, and signal components of various frequency bands input from the RF transmission module 460 (intermediate frequency). Signal components that are not needed in the process of synthesizing and amplifying may pass only the desired frequency and attenuate the signals in the remaining frequency bands. Pass it through.

The power amplification module 420 amplifies the RF signal passing through the transmission filter 440 into an RF signal having a transmittable power intensity and transmits the RF signal to the duplexer 410.

The baseband processor 500 includes a synchronous dynamic random access memory (SDRAM) to obtain an audio signal and a video signal from an intermediate frequency band signal, and the SDRAM stores a signal processing data.

The baseband processor 500 demodulates an intermediate frequency band signal to extract a baseband signal, and converts the lowband analog signal into a digital signal.

The baseband processor 500 includes an analog / digital signal converter (ADC, DAC), a fast fourier transform (FFT) circuit, a low pass filter (LPF), a modulator, an error correction circuit, and the like. In transmission, the digital signal is converted into an analog signal and then passed through a low pass filter to filter the low band signal.

SDRAM refers to the type of DRAM whose clock speed is synchronized with the main computing unit. The use of these SDRAMs allows the synchronization of clock speeds to increase the amount of signal that the processor can perform within a given time, thus increasing the RF front-end module. Used a lot for

As described above, the RF front end module 400 according to the present invention is implemented on a substrate. As described above, a circuit layout design considering isolation between electronic devices is a very important factor in improving a transmission / reception function. The isolation of the input / output stage 450 and the power amplifier module 420 is the most important factor.

At this time, the required isolation value should be at least 5 dB and at least 5 dB from the output of the receiving filter 450, and at least 64 dB and at least 60 dB from the input of the receiving filter 450.

Accordingly, as shown in FIG. 3, the reception filter 450 is disposed adjacent to the right side end on the substrate, and the power amplifier module 420 is disposed adjacent to the left side end on the substrate to maximize the isolation. Form.

In addition, in order to increase the isolation between the reception filter 450 and the power amplification module 420 as well as to improve the isolation between the components forming the receiver and the transmitter, an isolation wall based on the duplexer 410. This is further formed.

That is, the duplexer 410 is positioned at the upper end of the substrate and has a structure in which an isolation wall is disposed below to isolate the components forming the transmitting end and the components forming the receiving end.

Measuring the isolation value in this arrangement ensures sufficient isolation to maintain stable reception sensitivity.

4 is a diagram illustrating a ground pattern of a substrate on which the RF front end module 400 according to an embodiment of the present invention is implemented.

The substrate on which the RF front end module 400 according to the embodiment of the present invention is implemented is a multilayer structure, and has an improved ground layer structure to improve isolation between circuit elements, minimize parasitic components, and minimize the effects of signal crosstalk. To form.

According to FIG. 4, the left figure shows the upper ground layer 600, and the right figure shows the lower ground layer 700, the upper ground layer 600 being the antenna side pattern 610, the receiving end side. The three zone patterns of the pattern 630 and the transmitting end side pattern 620 are divided and formed.

However, in the lower ground layer 700, the antenna side pattern 710, the receiver end pattern 730, and the transmitter end side pattern portion 720 are opened to correspond to the upper ground layer 600, in particular, to minimize parasitic components. It has an advantageous structure.

The RF front-end module 400 according to the embodiment of the present invention described above has been described using a system for CDMA as an example, but a system for wideband CDMA (WCDMA) and a universal mobile telecommunications system (UMTS) based on a GSM communication standard It is possible to design a system as a combination of terrestrial wireless communication technology and satellite transmission technology to provide a communication service capable of transmitting broadband packet-based text, digitized voice or video and multimedia data at a high speed of 2 Mbps or more). The optimal layout structure is presented.

The present invention has been described above with reference to the preferred embodiments, which are merely examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible that are not illustrated above. 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, it is possible to provide an RF front-end module with improved transmission / reception function while minimizing size by providing a circuit structure that minimizes the influence of parasitic components and an arrangement structure of circuit elements that are improved to ensure sufficient isolation between circuit elements. It has an effect.

Claims (8)

A duplexer for filtering and selectively transmitting a signal transmitted and received through an antenna; A transmission stage for transmitting a signal of a transmission frequency band, a transmission stage comprising a power amplifier module amplifying the signal processed by the transmission filter for transmission to the duplexer and located adjacent to one end on a substrate; And A low noise amplification module for suppressing low noise components and amplifying a signal transmitted from the duplexer, and an RF front receiving receiver having a reception filter designed to pass only a signal of a reception frequency band and to be adjacent to the other side of the substrate. End module. The method of claim 1, wherein the transmitting end and the receiving end is RF front-end module, characterized in that separated by a separating wall on the substrate. The method of claim 1, wherein the duplexer Adjacent to one end on the substrate, the RF front end module being located at the center of the transmitting end and the receiving end. The method of claim 1, wherein the transmitting end And an RF transmitting module for controlling gain of a baseband signal and transferring the transmission signal to the transmission filter. The method of claim 1, wherein the receiving end And an RF receiving module for controlling and converting a gain of the RF signal transmitted from the receiving filter. The method of claim 1, wherein the substrate The multi-layer structure, wherein the ground pattern of the ground layer located below the RF front-end module, characterized in that the transmitting, receiving and antenna side pattern portion is opened. The RF front end module according to claim 1, wherein the isolation value between the output terminal of the power amplification module and the output terminal of the reception filter is 75 dB or more. The RF front end module according to claim 1, wherein the clearance value between the output terminal of the power amplifier module and the input terminal of the reception filter is 60 dB or more.

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