KR20010062844A - Intermodulation control device and method in a mobile communication system - Google Patents

Abstract

PURPOSE: A device for controlling an IMD(Intermodulation) of a mobile communication system is provided to simultaneously control the IMD from an LNA(Low Noise Amplifier) terminal and an IF(Intermediate Frequency) terminal. CONSTITUTION: An LNA(Low Noise Amplifier)(106) performs a low noise amplification for a high frequency receiving signal, and outputs the signal. The first switch(128) is connected with the LNA(106) in parallel, and switched according to the first control signal for controlling an IMD(Intermodulation). A frequency converter(116) performs a down conversion for an output of the LNA(106) as an IF(Intermediate Frequency) signal. An IF amplifier(118) amplifies the IF signal for outputting. The second switch(130) is connected with the IF amplifier(118) in parallel, and switched according to the second control signal for controlling the IMD. A controller(134) generates the first and the second control signal having levels decided according to an RSSI(Received Signal Strength Indicator) and an energy to noise ratio.

Description

Device and method for intermodulation control of mobile communication system {INTERMODULATION CONTROL DEVICE AND METHOD IN A MOBILE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for controlling an intermodulation (IMD) in a mobile communication system, and more particularly, to an apparatus and a method for controlling an IMD using a switch.

In general, the factors that are important in the field of radio frequency (RF) in designing a terminal of a mobile communication system are single tone desensitization and intermodulation spurious response attenuation. These two causes a lot of current consumption when designing a receiver (RX: Receiver), and it is a major cause of the price increase of terminal components. Therefore, many methods have been researched to reduce the current and improve the performance of the terminal while satisfying the minimum performance standard of the terminal for these factors.

Of these two factors, one should talk about the field of intermodulation spurious response attenuation related to the present invention. There are three items in the minimum performance standard for intermodulation spurious response attenuation (e.g., IS-98A Receiver Performance Intermodulation Spurious Response Attenuation Test) (shown in Table 1 below). It depends on the band. For example, only one item is used in the Personal Communication Services (PCS) frequency band, and the dual mode of CDMA and Advanced Mobile Phone System (AMPS) is used in the Code Division Multiple Access (CDMA) band (900 MHz). Three items are used. For the PCS, the circuit used to reduce the single tone sensitivity is not a problem since the intermodulation items also satisfy. However, for the CDMA, two items out of three items must be additionally controlled. Of the two items, the second item of -32dBm can be satisfied by controlling the current of the IF (Intermediate Frequency) amplifier, but the third item of -21dBm can never be controlled by the current alone. Therefore, in order to satisfy this third item, it is necessary to remove a very large level of harmonic components (jamming signal components), and to do so, the power (level of the received signal (two tone signals in the case of a test)) ) To reduce the effects of harmonic generation.

1 to 3 are diagrams showing the configuration of an intermodulation spurious response attenuation (hereinafter referred to as "IMD (Intermodulation)") control apparatus according to the prior art, to remove very large harmonic components. The IMD control apparatus according to the first example shown in FIG. 1 receives a diode 124 by connecting a diode 124 between a duplexer 104 and a low noise amplifier (LNA) 106 and a ground terminal. Reduce the level of the signal. The IMD control apparatus according to the second example shown in FIG. 2 connects the diode 126 between the surface acoustic wave filter (SAW) 108 and the mixer 116 and between the ground terminal. This reduces the level of the received signal. The IMD control apparatus according to the third example shown in FIG. 3 controls the level of the received signal by connecting a switch (SW) 128 in parallel to the LNA 106 and controlling the switch 128. Three methods according to the prior art as shown in Figures 1 to 3 are to reduce the level of the received signal to minimize the effects of harmonics caused by intermodulation in the LNA 106 and IF amplifier 118 .

The IMD control apparatus according to the prior art as described above is performing IMD control only at the radio frequency (RF) stage, that is, the LNA stage. As described above, when IMD control is performed in the LNA stage, a significant amount of current consumption (eg, 10 mA) occurs in an IF amplifier processing an intermediate frequency (IF) signal. In addition, there is a problem in that the performance of the terminal cannot be optimally improved because only IMD control is performed at the RF stage.

Accordingly, an object of the present invention is to provide an intermodulation control apparatus and method of a mobile communication system for solving the above problems.

Another object of the present invention is to provide an apparatus and method for reducing current consumption generated in a control process for minimizing the effects of intermodulation in a mobile communication terminal.

It is still another object of the present invention to provide an intermodulation control apparatus and method capable of optimally improving the performance of a mobile communication terminal.

An intermodulation control apparatus of a mobile communication system according to the present invention for achieving these objects is characterized by performing IMD control not only at the RF (LNA) stage but also at the IF stage. The intermodulation control device includes: a low noise amplifier for low noise amplifying and outputting a high frequency received signal; a first switch connected in parallel to the low noise amplifier and switched according to a first control signal applied for intermodulation control; A frequency converter for down-converting the output of the low noise amplifier to an intermediate frequency signal, an intermediate frequency amplifier for amplifying and outputting the intermediate frequency signal, and a second control connected in parallel to the intermediate frequency amplifier and applied for intermodulation control And a control unit for generating the first control signal and the second control signal having a level determined according to a received signal field strength and an energy-to-noise ratio.

1 is a view showing the configuration of an IMD control apparatus according to an example of the prior art.

2 is a view showing the configuration of an IMD control apparatus according to another example of the prior art.

3 is a view showing the configuration of an IMD control apparatus according to another example of the prior art.

4 is a view showing the configuration of an IMD control apparatus according to the present invention;

FIG. 5 is a diagram illustrating in detail a configuration of an stabilization circuit illustrated in FIG. 4. FIG.

6 is a view showing in detail the configuration according to another example of the stabilization circuit shown in FIG.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. Also, in the following description, many specific details such as components of specific circuits are shown, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. It will be self-evident to those of ordinary knowledge in Esau. In the following description of the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Terms to be described later are defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user or chip designer, and the definitions should be made based on the contents throughout the present specification.

4 is a diagram illustrating a configuration of an IMD control apparatus according to an embodiment of the present invention. The IMD control apparatus includes an LNA 128 for amplifying an RF signal, a mixer 116 which is a frequency converter for down-frequency converting the RF signal amplified by the LNA 128 into an IF signal, and an amplifier for amplifying the IF signal. In the mobile communication system (terminal) including the IF amplifier 118, not only the IMD control in the LNA stage but also the IMD control in the IF stage.

Referring to FIG. 4, the IMD control apparatus according to the embodiment of the present invention includes a switch (SW) 128 connected in parallel to the LNA 106, and also a switch connected in parallel to the IF amplifier 118 (SW) 130. Each of the switches 128 and 130 is for IMD control and is controlled by an IMD_PDM1 signal and an IMD_PDM2 signal provided from a control unit (so-called Mobile Station Modem (MSM) chip) 134, respectively. The switch 128 may be used integrally with the LNA 106, and the switch 130 may be integrated with the IF amplifier 118. That is, in the present invention, an LNA having a switching function may be used as the LNA 106, and an IF amplifier having a switching function may be used as the IF amplifier 118. A stabilization circuit 129 is connected between the control unit 134 and the switch 128, and a stabilization circuit 132 is connected between the control unit 134 and the switch 130. The stabilization circuit 129 and stabilization circuit 132 may be configured as shown in FIGS. 5 and 6 to be described later.

5 is a diagram illustrating a configuration of an example of the stabilization circuit 132 illustrated in FIG. 4. The other stabilization circuit 129 shown in FIG. 4 may be configured in the same manner as the stabilization circuit 132.

Referring to FIG. 5, the stabilization circuit 132 includes a loop filter 136 connected in series (forward) and a resistor (R). The IMD_PDM signal from the controller 134 is provided to switch control the switch 130 through the loop filter 136 and the resistor R.

The stabilization circuit 132 is an example implemented using a passive element.

6 is a diagram illustrating a configuration according to another example of the stabilization circuit 132 illustrated in FIG. 4.

Referring to FIG. 6, the stabilization circuit 132 includes a loop filter 136, resistors R1, R2, and R3, and a transistor Q. The transistor Q is an NPN transistor having a collector terminal, a base terminal and an emitter terminal. An input terminal of the loop filter 136 is connected to the control unit 134 to input an IMD_PDM signal. The output terminal of the loop filter 136 is connected to one side of the resistor R2, and the other side of the resistor R2 is connected to the base terminal of the transistor Q. One side of the resistor R1 is connected to the collector terminal of the transistor Q, and the other side of the resistor R1 is connected to the power supply voltage terminal VCC. The emitter terminal of the transistor Q is connected to the ground terminal and also connected to switch control the switch 130.

As shown in FIG. 4, the present invention uses the switch 128 for IMD control in parallel to the LNA 106, and the switch 130 for IMD control in the IF amplifier 118 in parallel. It is connected and used. The IMD_PDM1 signal controlling the switch 128 is provided from the control unit (MSM) 134, and the IMD_PDM2 signal controlling the switch 130 is provided from the control unit (MSM) 134. For example, the controller 134 may be an MSM2300 chip manufactured by Qualcomm. When the MSM2300 chip is used as the control unit 134, the control unit 134 includes RF control pins PDM1 and PDM2, which are pins for outputting the IMD_PDM1 signal and the IMD_PDM2 signal. Can be used as For example, the IMD_PDM1 signal may be output through the control pin PDM1 provided in the controller 134, and the IMD_PDM2 signal may be output through the control pin PDM2 provided in the controller 134. The controller 134 reads the values of the received signal strength indicator (RSSI) and the energy-to-noise ratio (Ec / Io or Eb / Nt), and selects a voltage level suitable for the situation of the IMD among a plurality of voltage levels. IMD_PDM1,2 signals may be generated. The received signal field strength and energy-to-noise ratio may be measured by a received signal field strength measuring unit (not shown) and an energy-to-noise ratio (not shown). The IMD_PDM1 signal is a signal having a voltage level that determines the switching on / off operation of the switch 128. The IMD_PDM2 signal determines the switching on / off operation of the switch 130. This signal has a voltage level. When the stabilization circuits 129 and 132 are configured as shown in FIG. 5, the voltage levels of the IMD_PDM1 and 2 signals may be determined in consideration of the difference between the input and output levels of the loop filter 136 and the level down by the resistor R. FIG. Can be. When the stabilization circuits 129 and 132 are configured as shown in FIG. 6, the voltage level of the IMD_PDM signal is displayed on the emitter terminal when the input / output level difference of the loop filter 136 and the signal are input to the base terminal of the transistor Q. It may be determined in consideration of the difference in the voltage level of the signal. The difference in voltage level between the base terminal and the emitter terminal of the transistor Q is adjustable according to the values of the resistors R1, R2, and R3.

In the above-described present invention, the control unit (MSM) 134 which connects the switch 128 in parallel to the LNA 106 and the switch 130 in parallel to the IF amplifier 118, and detects the situation of the IMD is performed by IMD_PDM1. Generates the two signals to operate the switches 128 and 130. In particular, using an amplifier with a switch function as the LNA 106 and the IF amplifier 118 will be easier to design. That is, if the IMD_PDM1, 2 signals corresponding to the voltage levels required for the operation of the switches 128 and 130 are generated and applied to the switches 128 and 130, the IMD problem is simply solved. In addition, since the received signal is passed directly to the switch (128,130), it is possible to eliminate the occurrence of ripple by just matching the impedance of both ends.

First, before describing the operation by the IMD controller according to the embodiment of the present invention shown in FIGS. 4 to 6, the items of CDMA and PCS for the Intermodulation Spurious Response Attenuation TEST will be described. Table 1 is as follows.

IS98-A Receiver performance intermodulation spurious response attenuation Parameter Ior (dBm / 1.23MHZ) Mobile Station Class ii, ⅲ Test 1 Test 2 Tone 1 offset from carrier + 900KHz -900KHz Tone power 1 -101 (1) -43 dBm -43 dBm -90 (2) -32 dBm -32 dBm -79 (3) -21 dBm -21 dBm Tone 2 offset from carrier + 1700KHz -1700KHz Tone power 2 -101 (1) -43 dBm -43 dBm -90 (2) -32 dBm -32 dBm -79 (3) -21 dBm -21 dBm Pilot Ec / Ior -7 dB -7 dB Traffic Ec / Ior -15.6 dB -15.6 dB

In Table 1, all three items (1) (2) and (3) are related to CDMA, and PCS is only related to the first item among the three items. In this case, the tone 1 offset from the carrier is 900 KHz, the tone 2 offset is 1700 KHz, and Ior means power of a signal that the terminal receives from a base station in a cell to which the terminal belongs. In the first test (test 1), tone 1 of +900 KHz and tone 2 of +1700 KHz are generated, and the generated tones and the received signal from the base station are received by the antenna of the terminal through a so-called jammer. In the second test (test 2), tone 1 of -900 KHz and tone 2 of -1700 KHz are generated, and the generated tones and the received signal from the base station are received by the antenna of the terminal through the jammer. At this time, the received signal from the base station has a different power value depending on the item.

Next, the operation principle of the new type IMD control apparatus proposed by the present invention will be described.

In Table 1, item 1 (-43dBm) is designed to satisfy a single tone sensitivity deterioration when the LNA 106 of FIG. 4 is designed, and thus, this single tone is naturally satisfied. Therefore, the problem is items 2 and 3. As described above, the RF interface control pin of the MSM2300 proposed by Qualcomm, which can be used as the controller 134, includes PDM1 and PDM2. Here, this control pin can be used according to user definition. Therefore, about 260 PDM signals can be generated in consideration of the RSSI value and the Eb / No value of the terminal. That is, if the experimental value is determined to be output at a desired level, the desired voltage can be applied to the switches 128 and 130.

Now, when a jamming signal is applied to the antenna 102 of FIG. 4, a relatively large signal is received compared to a signal that the terminal itself should receive. In this case, the LNA 102 is designed to satisfy a single tone sensitivity deterioration. Therefore, it is unreasonable to demand further performance improvement here. In fact, it can be said that the occurrence of such intermodulation by the dual tone occurs in the IF amplifier 118. The reason is that the dual tone signal is amplified together with the signal of the terminal itself up to the RF SAW filter 108 and the mixer 116 stage, and a signal level greater than the input of the LNA 106 is applied. Therefore, the IF amplifier 118 having the ICP1, which is relatively lower than the ICP1 (Input Compression Point 1dB) of the LNA 102, is absolutely affected by the intermodulation spurious response due to the dual tone. Therefore, when the jamming signal is received through the antenna 102, the control unit 134 generates the IMD_PDM signal having the desired voltage level and switches on the switch 48, thereby the LNA 106, the SAW filter 108, and the mixer ( Intermodulation by the IF amplifier 118 for the signal applied to the IF amplifier 118 via 116 is eliminated, and most of the signal is removed after passing through the IF filter 120, thereby minimizing the effects of the double tone. have.

As described above, the present invention proposes an apparatus for controlling IMD not only in the LNA stage but also in the IF stage. The present invention has the advantage of reducing the amount of current consumed in the IF stage compared to the case of IMD control only in the LNA stage by controlling the IMD at the same time as well as the LNA stage. In addition, the present invention has the advantage that the performance of the terminal can be optimally improved by controlling the IMD at both ends of the receiver.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (6)

A low noise amplifier for low noise amplifying and outputting a high frequency received signal; A first switch connected in parallel to the low noise amplifier and switched according to a first control signal applied for intermodulation control; A frequency converter for converting the output of the low noise amplifier down to an intermediate frequency signal; An intermediate frequency amplifier for amplifying and outputting the intermediate frequency signal; A second switch connected in parallel to the intermediate frequency amplifier and switched according to a second control signal applied for intermodulation control; And a control unit for generating the first control signal and the second control signal having a level determined according to a received signal electric field strength and an energy-to-noise ratio. The apparatus of claim 1, wherein the switches are integrated with the amplifiers. The apparatus of claim 1, further comprising a stabilization circuit connected between the control unit and the switches and stabilizing the control signals. 4. The apparatus of claim 3, wherein the stabilization circuit comprises a loop filter connected in series between the control unit and the switches and a resistor. 4. The apparatus of claim 3, wherein the stabilization circuit comprises a loop filter connected in series between the control unit and the switches and a transistor. A mobile communication including a low noise amplifier for low noise amplifying and outputting a high frequency signal, a frequency converter for converting the low noise amplified high frequency signal by falling frequency and outputting an intermediate frequency signal, and an intermediate frequency amplifier for amplifying and outputting the intermediate frequency signal. In the intermodulation control method of the system, Generating a first control signal and a second control signal having a voltage level determined according to the received signal field strength and the energy-to-noise ratio; Selectively amplifying the high frequency signal by the low noise amplifier according to the first control signal; And selectively amplifying the intermediate frequency signal by the intermediate frequency amplifier according to the second control signal.