Abstract:
The method for controlling a low noise amplifier (LNA) gain state which is applied to a receiver having the LNA is disclosed. The method includes the steps of: storing an LNA gain state of an idle mode when a state of the receiver transits an idle mode to a sleep mode; and returning to the stored LNA gain state when the receiver transits the sleep mode to the idle mode.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method for controlling a low noise amplifier (LNA) gain state; and, more particularly, to a method for controlling an LNA gain state in order to improve a receipt performance of a mobile terminal in a receipt electric-field environment where the LNA gain state is continuously changed.  
       DESCRIPTION OF RELATED ART  
       [0002]     Generally, a low noise amplifier (LNA) in a mobile terminal outputs an inter modulation distortion (IMD) component when two continuous waves are inputted. Such an IMD component distorts signals processed in the mobile terminal and it has become a major problem of signal processing in the mobile terminal causing degradation of the mobile terminal.  
         [0003]     When two signals of frequency f 1  and f 2  are inputted in to the LNA, a component of frequency outputted from the LNA can be represented as mf 1 ±nf 2 , wherein m and n are positive integers over 1. As the LNA gain increases, an influence of third components (i.e., 2f 1 -f 2  and 2f 2 -f 1 ) of the IMD component increases to triple times. Therefore, a variable-gain LNA is adapted in order to decrease the LNA gain in a high electric-field as shown in  FIG. 1A .  
         [0004]     Generally, states of the mobile terminal include a sleep mode and an idle mode in order to decrease battery consumption. When the mobile terminal is in the sleep mode, the transmitter and the receiver of the mobile terminal are deactivated and most circuits including a mobile terminal model (MDM) work in a low power consumption mode. Moreover, when the mobile terminal is in the idle mode, the receiver is activated to receive a call from a base station but the transmitter is deactivated.  
         [0005]     A state of a code division multiple access (CDMA) mobile terminal becomes to the sleep mode or to the idle mode in different ratio according to a slot cycle index (SCI). For example, when the SCI is 0, the mobile terminal becomes to the idle mode during 1 slot of total 16 slots (wherein, 1 slot is 80 ms) and remains in the sleep mode during the other 15 slots. At the same manner, when the SCI is 1, the mobile terminal becomes to the idle mode during 1 slot of total 32 slots and remains in the sleep mode during the other 31 slots. When a SCI is 2, the mobile terminal becomes to the idle mode during 1 slot of total 64 slots and remains in the sleep mode during the other 63 slots. Herein, the smallest value between the values of the SCI in the mobile terminal and the base station is determined as the value of the SCI. The base station determines time to wake up the terminal in the idle mode according to the determined value of the SCI. As mentioned above, the CDMA terminal becomes to the idle mode by controlling the ratio of the sleep mode and the idle mode based on the SCI, to thereby decrease a system load and extend the period of the battery usage.  
         [0006]      FIG. 1A  is a graph showing a LNA gain state in a calling mode in accordance with a prior art and  FIG. 1B  is a graph showing an LNA gain state in an idle mode in accordance with a prior art.  
         [0007]     As shown in  FIGS. 1A and 1B , the LNA gain state generally includes 4 steps. A first gain state (0) that is the highest state among the 4 steps and a forth gain state (3) is the lowest gain state.  
         [0008]      FIG. 2  is a flowchart describing steps for entering a sleep mode in a conventional LNA gain state controlling method.  
         [0009]     The LNA gain state of the LNA in the receiver of the mobile terminal setups as the forth gain state (3) that is the lowest gain state at step S 201 . Setting up the LAN gain state at step S 201  can be performed by following function. 
 
rf_set_Ina_decision_to_low_gain_state( ); 
 
         [0010]     Then, the mode of the receiver is transited to the sleep mode, i.e., the power down mode at step S 202 . Setting up the mode at step S 202  can be performed by following function. 
 
rfr_sleep_enable( ); 
 
         [0011]      FIG. 3  is a flowchart describing steps for entering an idle mode in a conventional LNA gain state controlling method.  
         [0012]     The LNA gain state of the LNA setups as the forth gain state (3) that is the lowest gain state at step S 301 . Setting up the LAN gain state at step S 301  can be performed by following function. 
 
rf_set_Ina_decision_to_low_gain_state( ); 
 
         [0013]     Then, an automatic gain control (AGC) function is deactivated at step S 302 . The AGC function is a function for determining an AGC value according to receipt electric-field intensity and controlling the LNA gain according to the determined AGC value. Setting up the AGC function at step S 302  can be performed by following function. 
 
HWIO_OUTM(AGC_RDWR_CTL, CAGC_AGC_OVRD_M, CAGC_AGC_FRZ_V); 
 
         [0014]     Then, the AGC value sets as a value of the lowest gain state, i.e., the forth gain state (3) at step S 303 . Setting up the AGC value at step S 303  can be performed by following function. 
 
rf_set_agc_value_to_low_gain( ); 
 
         [0015]     Then, the mode of the receiver is transited to the idle mode at step S 304 . Setting up the mode at step S 304  can be performed by following function. 
 
rfr_cdma_wakeup( ); 
 
         [0016]     Then, the LNA is activated at step S 305 . Setting up the LAN gain state at step S 305  can be performed by following function. 
 
RF_LNA_STATE_MACHINE_NORMAL( ); 
 
         [0017]     Then, the AGC function is activated at step S 306 . Setting up the AGC function at step S 306  can be performed by following function. 
 
HWIO_OUTM(AGC_RDWR_CTL, CAGC_AGC_OVRD_M, CAGC_AGC_NRM_V); 
 
         [0018]     Operations of the above mentioned conventional LNA gain state controlling method are described hereinafter.  
         [0019]     A table 1 presents a result of measuring an E c /I o  (in dB) of a pilot channel of the mobile terminal according to intensity of received electric field. The E c /I o  is average energy, wherein E c  is energy integrated during one pseudo noise (PN) chip period and I o  is a total receipt power spectrum intensity including a noise measured at an antenna connection. As the E c /I o  increases, a reception rate in a field becomes increased.  
                                                                         TABLE 1                                   −85 dBm   −87 dBm   −89 dBm   −91 dBm   −93 dBm   −95 dBm                                    First gain state   −6.0˜−7.5   −6.0˜−7.5   −6.0˜−7.5   −6.0˜−7.5   −7.0˜−8.0    −7.0˜−8.0        Second gain state   −7.0˜−8.0   −7.0˜−8.0   −7.5˜−8.5   −8.0˜−9.0   −8.5˜−10.0   −9.5˜−11.0                  
 
         [0020]     By Referring to  FIG. 1B , it can be estimated that a gain is switched at a specific electric field value (which will be referred to as a switching point hereinafter) because the terminal operates as the gain state is switched from the high electric-field in the conventional idle mode.  
         [0021]     It is assumed that a switching point that the LNA switches from the first gain state (0) to the second gain state (1) is as −91 dBm, the electric-field value is −93 dBm and the receiver wakes up in the idle mode from the sleep mode.  
         [0022]     Under the above assumption, if the electric-field value becomes strong as −89 dBm after the receiver wakes up in the idle mode, the LNA switches to the second gain state (1) according to  FIG. 1B .  
         [0023]     Then, the LNA gain is switched according to  FIG. 1A . Because a hysterisis range, where the first gain state (0) is changed to the second gain state (1), is from −91 dBm to −86.2 dBm, the second gain state (1) is maintained until the electric-field value becomes weaker as −91 dBm.  
         [0024]     If the receiver does not transit to the sleep mode, the first gain state (0) is maintained although the electric-field value becomes strong as −89 dBm according to  FIG. 1A .  
         [0025]     As referring to the table 1, the E c /I o  becomes increased by 1.5 bB since the mode is transited to the sleep mode under the above assumption and thereby the receipt rate becomes decreased.  
         [0026]     As mentioned above, the LNA gain state of the LNA in the receiver of the mobile terminal is forcibly switched to the forth gain state (3) when the mode is transited from the idle mode to the sleep mode. Therefore, when the mode is re-transited from the sleep mode to the idle mode, the LNA gain is controlled as like as controlling of the LNA gain in the high electric-field. Accordingly, if there is the electric-field value in the hysterisis range as shown in  FIG. 1A , the LNA gain is switched to one step lower state than the state in the idle mode before the conversion. Therefore, the receipt rate becomes degraded.  
       SUMMARY OF THE INVENTION  
       [0027]     It is, therefore, an object of the present invention to provide a method for controlling LNA gain state by always maintaining an LNA gain state as an advantageous gain state in order to improve receipt performance for a mobile terminal having a receiver.  
         [0028]     In accordance with an aspect of the present invention, there is provided a method for controlling a low noise amplifier (LNA) gain state which is applied in a receiver including the LNA, the method including the steps of: a) storing an LNA gain state of an idle mode when the receiver becomes a sleep mode from an idle mode; and b) returning to the LNA gain state stored at step a) when the receiver becomes an idle mode from a sleep mode.  
         [0029]     In accordance with another aspect of the present invention, there is provided a method for controlling a low noise amplifier (LNA) which is applied to a receiver including lower edge and higher edge according to a hysterisis range by using multiple LNA gain states according to an electric-field value, the method including the steps of: a) storing a first reference electric-field value which is a lower edge of an LNA gain state of an idle mode when the receiver becomes the sleep mode from the idle mode; and b) adjusting the LNA gain state by referring to current field value after returning to the LNA gain state according to the second reference field value when the receiver becomes the idle mode from the sleep mode.  
         [0030]     In accordance with another aspect of the present invention, there is provided a method including the steps of: acquiring a current LNA gain state and storing the first reference electric-filed value which is a lower edge in order to come to the current LNA gain state; setting the LNA gain state of the LNA into a lowest implemented gain state; and transiting a mode of the receiver into the sleep mode. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]     The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:  
         [0032]      FIG. 1A  is a graph showing a low noise amplifier (LNA) gain state in a calling mode in accordance with a prior art;  
         [0033]      FIG. 1B  is a graph showing an LNA gain state in an idle mode in accordance with a prior art;  
         [0034]      FIG. 2  is a flowchart describing steps for entering a sleep mode in a conventional LNA gain state controlling method;  
         [0035]      FIG. 3  is a flowchart describing steps for entering an idle mode in a conventional LNA gain state controlling method;  
         [0036]      FIG. 4  is a flowchart describing a method for controlling an LAN gain state in order to enter a sleep mode in accordance with a preferred embodiment of the present invention; and  
         [0037]      FIG. 5  is a flowchart describing a method for controlling an LNA gain state in order to enter an idle mode in accordance with a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]     Hereinafter, a method for controlling an LNA gain state will be described in detail with reference to the accompanying drawings.  
         [0039]      FIG. 4  is a flowchart describing a method for controlling an LNA gain state in order to enter a sleep mode in accordance with a preferred embodiment of the present invention.  
         [0040]     At first, current LNA gain state is obtained and a reference electric-field value is stored at step S 401 , where the reference electric-field value is an electric field value of a lower edge for attaining the current LNA gain state. The step S 401  can be described in a program code as follows. The reference electric-field value is not limited to the lower edge and it can be a value that reflects the current gain state (e.g., a value under the lower edge). 
 
Ina_gain_state_before_sleep=rf_get_Ina_gain_state( ); 
 
         [0041]     Then, the LNA gain state of the LNA in the receiver of the mobile terminal is determined as the forth gain state (3) that is a lowest gain state at step S 402 . The step S 402  is described in a program code as follows. 
 
rf_set_Ina_decision_to_low_gain_state( ); 
 
         [0042]     Then, the mode of the receiver is transited to the sleep mode, i.e., the power down mode at step S 403 . The step S 403  is described in a program code as follows. 
 
rfr_sleep_enable( ); 
 
         [0043]     Therefore, when the receiver transits the idle mode into the sleep mode, the LNA gain state before transiting is stored by storing the reference electric-field value which is the lower edge of the LNA gain state in the idle mode.  
         [0044]      FIG. 5  is a flowchart describing a method for controlling an LNA gain state in order to enter an idle mode in accordance with a preferred embodiment of the present invention.  
         [0045]     At first, the LNA gain state of the LNA is determined as the forth gain state (3) that is the lowest gain state at step S 501 . The step S 501  can be described in a program code as follows. 
 
rf_set_Ina_decision_to_low_gain_state( ); 
 
         [0046]     After determining the LNA gain state of the LNA, automatic gain control (AGC) function is deactivated at step S 502 . The AGC function is a function for determining an AGC value according to the receipt electric-field intensity and controlling the LNA gain according to the determined AGC value.  
         [0047]     The step S 502  can be described in a program code as follows. 
 
HWIO_OUTM(AGC_RDWR_CTL, CAGC_AGC_OVRD_M, CAGC_AGC_FRZ_V); 
 
         [0048]     Then, the AGC value is determined as a value of the lowest gain state at step S 503 . The step S 503  is described in a program code as follows. 
 
rf_set_agc_value_to_low_gain( ); 
 
         [0049]     Then, the mode of the receiver is transited to the idle mode at step S 504 . The step S 504  is described in a program code as follows. 
 
rfr_cdma_wakeup( ); 
 
         [0050]     The AGC value is determined according to the reference electric-field value at step S 505 . Thus, when the method in  FIG. 4  is processed, the gain state is switched to the LNA gain state stored before the mode is transited from the idle mode to the sleep mode and the step S 505  can be described in a program code as follows. 
 
rf_set_agc_val_to_gain_before_sleep(Ina_gain_state_before_sleep); 
 
         [0051]     Then, the LNA is activated at step S 506 . The step S 506  can be described in a program code as follows. 
 
RF_LNA_STATE_MACHINE_NORMAL( ); 
 
         [0052]     The AGC function is activated at step S 507 . The step S 507  can be described in a program code as follows. 
 
HWIO_OUTM(AGC_RDWR_CTL, CAGC_AGC_OVRD_M, CAGC_AGC_NRM_V); 
 
         [0053]     Therefore, the current electric-field value is attained by using the AGC function and the LNA gain state is determined according to the current electric-field value.  
         [0054]     By Referring to the table 1, operations of the present invention are described hereinafter.  
         [0055]     It is assumed that the hysterisis range sets as −91 dBm to −86.2 dBm, the electric-field value is −93 dBm in the idle mode, the mode of the receiver is transited to the sleep mode and re-transited from the sleep mode to the idle mode. Under the above assumption, the lower edge value −91 dBm is stored before the receiver transits to the sleep mode, wherein the lower edge value is lower edge value making the gain state to be switched to the first gain state (0) of −93 dBm.  
         [0056]     In case of conventional method as mentioned above, if the electric-field value becomes −89 dBm after the mode is transited to the idle mode, the LNA is operated as like as the LNA is operated in high electric field after the mode of LNA is transited to the sleep mode since the LNA forcibly becomes in the fourth gain state (3) and then the LNA is maintained in the second gain state (1). However, in the present invention, the lower edge value switching the LAN into the first gain state (0) sets as 91 dBm and it reflects to −89 dBm of the current electric-field value after the LNA is switched to the first gain state (0). Therefore, −89 dBM of the current electric-field value is weaker electric field comparing to the upper edge value −86.2 dBm and accordingly, the LNA is maintained in the first gain state (0). That is, the present invention prevents decrease of the E c /I o  by 1.5 dB due to mode transition to the sleep mode.  
         [0057]     As mentioned above, the method of the present invention can be embodied as a set of computer executable instructors and stored in computer readable recording media such as a CD-a ROM, a RAM, a floppy disk, a hard disk and a magneto-optical disk.  
         [0058]     As mentioned above, the present invention can increase the receipt efficiency by maintaining the LNA gain state as the advantageous gain state reflecting the hysterisis range of the calling mode.  
         [0059]     The present application contains subject matter related to Korean patent application No. 2004-16852, filed in the Korean intellectual Property Office on Mar. 12, 2004, the entire contents of which being incorporated herein by reference.  
         [0060]     While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.