JP4684842B2 - Transmission output control device - Google Patents

Description

  The present invention relates to a transmission output control apparatus in a mobile phone, a small information terminal, or the like.

In recent years, the PCS band duplexer has been changed from a dielectric element to a SAW element, particularly with the downsizing of mobile phones for overseas use. SAW elements are currently inferior in power resistance compared to dielectric elements.
As shown in FIG. 5, it is assumed that the mobile phone x having the SAW element moving in the area Z of the base station X communicates using the 1150 channel. When leaving the area Z of the base station X and entering the area z of the base station Y to communicate with the base station Y, the mobile phone x hands off from the 1150 channel to another channel, for example, 25 channel. Since the mobile phone x has entered the area z of the base station Y, the distance to the base station Y is large, and the mobile phone x must be handed off at the maximum output.

  When handoff from channel 1150 to channel 25, the output of mobile phone x decreases. Therefore, the output drop is corrected by some means, but when outputting 6dBm in 1150 channels, handoff to 25 channels only outputs 3.2dBm, so the difference must be corrected by 2.8dB. I must. If this correction is performed at the maximum output, an overshoot may occur and the SAW element of the mobile phone x may be destroyed.

As a means for preventing this overshoot, it is conceivable that an element for suppressing power is added to the circuit, or power detection is performed with an interrupt signal every 100 msec and power control is performed in comparison with an expected value.
Moreover, although the means for correcting overshoot is described in Japanese Patent No. 30288802, it suppresses the adverse effect of overshoot generated by the own device on other devices, and does not solve the above problem.
Japanese Patent No. 30288802

  However, adding an element for suppressing power to the circuit is not possible because there is no such element in the high frequency region. In addition, if power is detected with an interrupt signal every 100 msec and power control is performed in comparison with the expected value, overshoot may occur during 100 msec from when handoff is performed until actual correction is performed. Does not solve the problem.

  Accordingly, an object of the present invention is to provide a transmission output control device that can satisfactorily suppress overshoot that occurs when correcting a decrease in output that occurs when handoff is performed.

  A transmission output control apparatus according to the present invention is a transmission output control apparatus that transmits a signal input from an antenna after amplification by adding a signal input to a power amplification circuit via a level control circuit, and includes a transmission output in a reference channel and a transmission output in another channel. And a first storage means for storing a signal representing the difference output between the first correction value and a control signal for outputting a transmission output smaller than the maximum transmission output in the reference channel when handoff is performed as a boundary. Second storage means for storing a second correction value for performing a correction smaller than the correction by the value, and switching from the correction by the first correction value to the correction by the second correction value when the boundary is exceeded And a control means.

The control signal at the boundary is a value in the vicinity of the control signal given to the level control circuit in order to output the maximum transmission output.
The other channel is one of a plurality of channel groups obtained by dividing a large number of channels, and one first correction value and one second correction value are set for each channel group. And

  Further, the second correction value is a signal indicating a correction weight.

  According to the present invention, when handoff occurs in a state where the maximum transmission output is output, it is possible to suppress the overshoot caused by correcting the decrease in the transmission output, so that the duplexer provided in the transmission circuit can be suppressed. Even if a SAW element is used, an excessive power is applied to the element without causing destruction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the antenna 1 is connected to a duplexer 3 via an antenna connector terminal 2. The duplexer 3 is generally used to send a transmission signal sent from the power amplification circuit 6 to the antenna 1 side and send a reception signal inputted from the antenna 1 to the reception circuit connection terminal 5. 4 is an isolator.

A transmission signal is supplied from the modulation circuit 8 to the power amplification circuit 6 via the level adjustment circuit 7. A modulated signal as an input signal is supplied to the input terminal 8a of the modulation circuit 8, and a modulation signal is supplied to the input terminal 8b. The level of the output signal of the modulation circuit 8 is adjusted by the level control circuit 7.
The control microcomputer 9 is provided with a first storage circuit 9a, a second storage circuit 9b, a control signal generation circuit 9c, an addition circuit 9d, and an arithmetic circuit 9e. A control signal, which is an output signal of the control signal generation circuit 9c, is added to the correction signal by the addition circuit 9d and added to the level control circuit 7 as a control signal. A level command signal from the base station received by the receiving circuit is applied from the terminal 11 to the control signal generating circuit 9c. The memory circuits 9a and 9b use nonvolatile memories.

  The output signal of the power amplifier 6 is applied to the isolator 4 and simultaneously to the DC voltage conversion circuit 10 via the detection coupling capacitor 6a. The output of the DC voltage conversion circuit 10 is applied to the control signal generation circuit 9c. The output of the transmission power measuring circuit 12 is applied to the storage circuits 9a and 9b. This transmission output measuring circuit 12 is provided separately from the main body of the mobile phone, and is used for manufacturing a mobile phone and storing a signal in its memory circuit. Is used.

The input signal applied to the terminal 8 a is modulated by the modulation circuit 8, controlled to a predetermined level by the level control circuit 7, and enters the power amplifier 6. The signal is amplified here and transmitted from the antenna 1 through the isolator 4, the duplexer 3, and the antenna connector terminal 2.
How to be controlled by the level control circuit 7 will be described. First, the terminal of the transmission power measurement circuit 12 is connected to the antenna connector terminal 2. Then, the antenna 1 is disconnected from the antenna connector terminal 2. The power of the transmission signal is measured by the transmission power measurement circuit 12 and stored in the first storage circuit 9a. The magnitude of the input signal at the input terminal 8a is constant, and the amplitude of the output signal of the level control circuit 7 is changed from a small value to a large value by a control signal (a correction signal described later is 0) by the control signal generation circuit 9c. Let

Then, for example, as shown in FIG. 2, the transmission output measuring circuit 12 outputs signals of levels A, B, C,. Based on this signal, control signals a, b, c,... J corresponding to A, B, C,.
At the same time, the detection signals (transmission power signals) a1, b1, c1,... J1 which are outputs of the DC voltage conversion circuit 10 are associated with the control signals a, b, c,. Is remembered.

This operation is performed for each mobile phone. When the operation is completed, the transmission power measurement circuit 12 is disconnected from the antenna connector terminal 2 and the antenna 1 is connected to the antenna connector terminal 2.
When the mobile phone is turned on, there is still no level command signal for the base station at the terminal 11, so that the control microcomputer 9 outputs a control signal corresponding to the input sensitivity of the signal received from the base station after the power is turned on. 1 is taken out from the storage circuit 9 a and given to the level control circuit 7, and a transmission output is outputted from the antenna 1. When the level command signal is received from the base station, the level command signal is input to the terminal 11.

This level command signal is given to the control signal generating circuit 9c, and an appropriate control signal is selected from the first memory circuit 9a and taken out to the level control circuit 7. The level command signal is a signal for raising or lowering the output level, and a control signal is selected by this signal. By this control, a signal having a transmission level desired by the base station is transmitted from the antenna 1.
When the control microcomputer 9 cannot receive the level command signal from the base station, the control microcomputer 9 repeats the operation of increasing the transmission output and confirming reception of the level command signal from the base station.

In this control, the output of the DC voltage conversion circuit 10 is applied to the control signal generation circuit 9c, and is compared with the transmission power signal of the first storage circuit 9a once every 100 msec. The applied control signal is monitored. That is, the level of the transmission signal is monitored.
Next, the contents stored in the second memory circuit 9b will be described. As shown in FIG. 3, channels 0 to 1200 are divided into 16 to form channel groups 0 to 15. The column “center” in FIG. 3 indicates the center channel in each channel group. The channel 1150 of the channel group 15 is set as a reference channel. The channel frequency shown in FIG. 3 shows an example of implementation.

  Now, assuming that transmission is performed on 1150 channels, the transmission output in the control signal (AGC level) a given to the level control circuit 7 when the mobile phone is closest to the base station is measured by the transmission output measurement circuit 12 and the arithmetic circuit It is stored as P1 in the second memory circuit 9b via 9e. The actual measurement value in this case is, for example, 6 dBm. It is the value of the vertical axis (transmission output) on the horizontal axis (AGC level) a shown in FIG. Similarly, the transmission output is measured for each channel group, and A1, B1,... N1, P1 are stored in the second memory circuit 9b. The arithmetic circuit 9e calculates P1-A1 to create a correction value 1, which is stored as a2 in the second memory circuit 9b. Similarly, each channel group is calculated and stored as b2, c2,... O2, p2.

The actually measured value of A1 is 3.2 dBm as shown in FIG. 4, and the correction value 1a2 is 6 dBm-3.2 dBm = 2.8 dB.
Next, the characteristic curve X of the reference channel 1150 shown in FIG. 4 is stored in the second memory circuit 9b. The AGC level is changed and the output of 1150 ch at that time is stored. Memory should be stored at appropriate intervals. Of course, the more points that are stored, the more accurately the curve can be stored.

  Further, the transmission output for each channel group in the control signal h when the mobile phone is outputting the maximum power far from the base station is stored in the second storage circuit 9b (this value is not shown in FIG. 3). Then, the transmission output for each channel group in the control signal h from the transmission output in the control signal h in the reference channel 1150ch is subtracted by the arithmetic circuit 9e to obtain the correction value 2 in the storage circuit 9b as aa, bb,..., Nn, pp As memory. Specifically, the correction value 2 is pp = 0 dB for the reference channel 1150 ch, and aa = 1.2 dB for the channel 25. Other channel groups take values between 0 and 1.2 dB. In this way, the correction values 1 and 2 are stored in the second memory circuit 9b. When the memory is completed, the transmission power measuring circuit 12 is disconnected from the antenna connector terminal 2.

Further details will be described with reference to FIG. Curve X is the characteristic of reference channel 1150ch, and curve Y is the characteristic curve of channel 25ch. To correct 2.8 dB, the AGC level needs to be changed from a to a + a3. When one input of the adder circuit 9d in FIG. 1 is a and the other input is a3, the control signal a + a3 is applied to the level control circuit 7.
When hand-off of the use channel of the cellular phone from 1150 ch to 25 ch, the transmission output decreases by 2.8 dB at AGC level a. Therefore, when the AGC level is changed from a to a + a3 to return to the original level, correction of 2.8 dB is performed. The value of a3 is obtained as follows. Since the slopes of the curve X and the curve Y shown in FIG. 4 are almost the same, the stored information on the curve X is added from the second storage circuit 9b to the arithmetic circuit 9e. At the same time, the correction value a2 stored in the second memory circuit 9b is added to the arithmetic circuit 9e, and a3 is obtained by calculation from both.

  When the AGC level is changed from h to h + h4 (corresponding to a3) in order to correct the value of the curve Y at the AGC level h (the AGC level when the maximum output is output in the reference channel 1150ch) by 2.8 dB, the point Z It is corrected to. This greatly exceeds the maximum output level (22.5 dBm) (for example, 1.6 dB). Such a state is the overshoot phenomenon described in the conventional example, and this overshoot may destroy the SAW element of the duplexer of the mobile phone.

  Therefore, in the embodiment of the present invention, taking the case of handoff from 1150 ch to 25 ch as an example, the AGC level is changed from a to g (a transmission level slightly lower than the maximum output level 22.5 dBm when the reference channel 1150 ch is used, dB). A value up to about 10% lower) is a correction value 1 (2.8 dB), and a value from g to h is a correction value 2 (1.2 dB). In this case, since the correction is made in small steps from the point g, the point Z becomes the point ZZ as compared with the case where the correction is performed for the entire period of 2.8 dB. That is, the AGC level for correction does not need to be increased as in h4, and h3 is sufficient.

  A description will be given with reference to FIG. Consider a case where a signal indicating 25 ch is applied from the used channel detection circuit 13 to the control signal generation circuit 9 c. For example, when the mobile phone is near the base station, the control signal a shown in FIG. 2 is extracted from the first storage circuit 9a and added to the adding circuit 9d. Further, a signal is applied from the control signal generating circuit 9c to the second memory circuit 9b, and the correction value 1 (2.8 dB) a2 and the curve X information shown in FIG. 3 are sent from the second memory circuit 9b to the arithmetic circuit 9e. Added. The arithmetic circuit performs the above-described arithmetic operation, and a corrected AGC signal a3 is obtained and applied to the adding circuit 9d via the control signal generating circuit 9c. The signal a + a3 is added from the adding circuit 9d to the level control circuit 7 as an AGC signal. As a result, the output of 25ch is corrected by 2.8 dB and becomes the same level as the output level of the reference channel 1150.

  When the mobile phone is away from the base station and is in a remote place, the mobile phone must increase the transmission output. Therefore, for example, as shown in FIG. 4, it is assumed that the AGC level h (control signal in FIG. 2) is added from the control signal generating circuit 9c to the adding circuit 9d. At this time, the transmission output is set in advance by the control signal generation circuit 9c, for example, 20 dBm (a transmission level slightly lower than the maximum output level 22.5 dBm when the reference channel 1150ch is used, a value almost 10% lower than dB, 4 is detected in advance, and when the transmission level exceeds this level, another signal is sent to the second memory circuit 9b. , The correction value 2 (1.2 dB) and the curve X information shown in FIG. 3 are extracted from the second memory circuit 9b and added to the arithmetic circuit 9e.

  A correction control signal h3 necessary for 1.2 dB correction by the arithmetic circuit 9e is generated and applied to the adder circuit 9d through the control signal generation circuit 9e. The output of the adder circuit 9d is h + h3, and the output of 25ch is corrected by 1.2 dB so as to be suppressed near the maximum output level, and the above-described overshoot is prevented from occurring. Thus, the correction state is switched at the point g in FIG. This switching is executed by detecting the boundary by a control circuit provided in the control signal generation circuit 9c.

The other channels are similarly controlled.
In FIG. 3, the transmission power value to be corrected is stored as the correction value 2. However, the weight of the correction value may be stored. That is, (correction value at 6 dB−overshoot value / 6 correction value at 6 dB) = 2.8−1.6 / 2.8 = 0.43 is stored. In this case, the weight applied to the arithmetic circuit 9e is eventually multiplied by the correction value of 6 dB to calculate the correction value 2 in FIG. 3, and the same result as described above is obtained. It should be noted that the correction value weight may be coarse correction such as dividing the 16 channel groups into three weights, for example.

Further, when the mobile phone is close to the base station, that is, when the AGC level in FIG. 4 is in the vicinity of a, the correction may be made only when the overshoot occurs.
In the embodiment, the description has been made with the expression of a circuit such as the control signal generating circuit 9C. However, it may be configured by software, and there may be a control means, a first storage means, a second storage means, a calculation means, and an addition means. .

  The present invention is useful for a transmission device such as a mobile phone.

It is a block diagram of the transmission output control apparatus in one Example of this invention. It is a figure which shows the table | surface for the apparatus description. It is a figure which shows the table | surface for the apparatus description. It is a characteristic view for explanation of the device. It is a figure for description of the conventional device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Antenna 2: Connection connector 3: Duplexer 4: Isolator 5: Reception circuit connection terminal 6: Power amplifier circuit 7: Level control circuit 8: Modulation circuit 9: Control microcomputer 9a: 1st memory circuit 9b: 2nd memory circuit 9c: Control signal generation circuit 9d: Addition circuit 9e: Arithmetic circuit 10: DC voltage conversion circuit 12: Transmission power measuring device 13: Used channel detection circuit

Claims (5)

Adding the signal input to the power amplifier circuit, a transmission output control unit that transmits from post-amplification antenna,
A signal representing the difference output between the transmission output in the reference channel and the transmission output in the other channel in which the value of each transmission output when the level of the input signal is changed to a plurality of values is stored as the first correction value. First storage means for
When the handoff between base stations, the maximum transmission power smaller than the transmission output in a range that does not overshoot in the standards channel, and boundary predetermined level to issue as the transmission output of the channel to be used after the handoff, the first Second storage means for storing a second correction value for performing a correction smaller than the correction by the correction value;
Control means for switching from the correction by the first correction value to the correction by the second correction value when the boundary of the predetermined level is exceeded;
Transmission output control apparatus characterized by comprising a. The other channel is one channel among a plurality of channel groups obtained by dividing a number of channels according to the order of transmission frequencies, and one first correction value and one second correction value are set for each channel group. it has transmission output control apparatus according to claim 1, wherein. The second correction value is
(First correction value−overshoot value from the maximum transmission output) / first correction value
The transmission power control apparatus according to claim 1, wherein the transmission power control apparatus is a signal indicating a correction weight given by: 2. The transmission according to claim 1, wherein the second correction value is a value obtained by subtracting a transmission output of each channel in the control signal for outputting the maximum transmission output from the maximum transmission output of the reference channel. Power control device. 2. The transmission power control apparatus according to claim 1, wherein the reference channel is a channel having a characteristic of obtaining a maximum output when the same level is given.

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