JP2000323999A - Transmission power control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control transmission power in a wide dynamic range and to eliminate the overshooting and undershooting of the transmission power. SOLUTION: The output signal of a 1st attenuator 31 to which a high-frequency signal is inputted is outputted to a main transmission line A or subordinate transmission line B through a changeover switch 32. The main transmission line A is provided with a 2nd attenuator 38 and an amplifier 33. A microcomputer 100 controls the gains of the 1st and 2nd attenuators 31 and 38 and the switching of the changeover switch 32; when the subordinate transmission line B is switched to the main transmission line A, the gain of the 1st attenuator 31 is varied while the gain of the 2nd attenuator 38 is held as it is and when the subordinate transmission line B is switched to the main transmission line A, the gain of the 2nd attenuator 38 is varied while the gain of the 1st attenuator 31 is held as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband C
The present invention relates to a transmission power control circuit used for a radio device such as a mobile phone using a DMA (Code Division Multiple Access) method.

[0002]

SUMMARY OF THE INVENTION Wideband CDM
A wireless device such as a mobile phone using the A (W-CDMA) system uses a chip rate of 4.096 Mcps according to the CDMA standard, so that a clock of 4.096 MHz × N times is generated and transmitted from the base station. To be synchronized with the signal frequency.

In this case, the wireless device is configured as shown in FIG. 7, for example. In the figure, 1 is a quadrature modulator, 2 is a transmission band limiting filter, 3 is a transmission power control circuit, 4 is a duplexer, 5 is an antenna, 6 is a 1.95 GHz band frequency switching synthesizer, 7 is a 190 MHz fixed frequency synthesizer, 8 is a reception high frequency low noise amplifier, 9 is a reception high frequency band limiting filter, 10 is a frequency mixer (mixer), 11 is a reception IF amplifier, 12 is a 190 MHz band restriction filter, and 13 is a quadrature demodulator.

In such a configuration, at the time of transmission, the quadrature modulator 1 outputs a channel switching frequency (1.9) output from the 1.95 GHz band frequency switching synthesizer 6.
2 to 1.98 GHz), and perform orthogonal transform using the signal.
After the transmission band is restricted by the transmission band limiting filter 2, the power is controlled by the transmission power control circuit 3, and the transmission is performed from the antenna 5 via the duplexer 4.

At the time of reception, a signal (frequency: 2.11 to 2.1) input from the antenna 5 via the duplexer 4
7 GHz signal) is low-noise amplified by the reception high-frequency low-noise amplifier 8, and the reception high-frequency band limiting filter 9 limits the reception high-frequency band. Thereafter, when the frequency mixer 10 performs frequency mixing using the signal of the channel switching frequency output from the 1.95 GHz band frequency switching synthesizer 6, a 190 MHz signal is obtained. And
The signal is amplified by the receiving IF amplifier 11 and
After the band is limited by the z band limiting filter 12, the quadrature demodulator 13 performs quadrature demodulation using the 190 MHz signal output from the 190 MHz fixed frequency synthesizer 7.

FIG. 8A shows a specific configuration of the transmission power control circuit 3 described above. As shown in the figure, the transmission power control circuit 3 inputs a modulated high-frequency signal as an input signal, and attenuates the input signal by an amount corresponding to a control voltage from a control device such as a microcomputer (not shown). It comprises an attenuator 21 for outputting, and a power amplifier 22 for amplifying an output signal of the attenuator 21 with a preset gain and supplying the amplified output signal to the antenna 5 as a transmission output signal. Then, in the transmission power control circuit 3, as shown in FIG. 8B, by increasing or decreasing the amount of attenuation of the attenuator 21,
Transmission power is controlled.

However, in the transmission power control circuit 3 described above, it is difficult to control the transmission power over a wide dynamic range because the dynamic range (variable range) of the attenuation in the attenuator 21 is limited. Therefore, the present applicant has previously proposed a transmission power control circuit capable of controlling transmission power over a wide dynamic range (Japanese Patent Application No. 10-269830). FIG. 9 shows a specific configuration of this.

The transmission power control circuit 3 inputs a modulated high-frequency signal as an input signal, and attenuates the input signal by an attenuation amount that changes according to a control voltage as a control signal (in other words, An attenuator 31 serving as a variable gain circuit that outputs (amplified by a negative gain that changes according to the control voltage) and outputs an output signal of the attenuator 31 to one of a first output terminal 32a and a second output terminal 32b From one side,
A changeover switch (high-frequency switch) 32 as a changeover circuit that selectively outputs the changeover signal in accordance with a switch changeover signal, and a signal output from a first output terminal 32a of the changeover switch 32 are converted by a preset positive gain GA. A power amplifier 33 for amplifying and outputting, a main transmission line A for transmitting an output signal of the power amplifier 33 to the antenna 5 as a transmission output signal, and one end connected to a second output terminal 32 b of the changeover switch 32. The sub-transmission line (bypass line) B, one end is connected to the sub-transmission line B, the other end is connected to the terminator 4a, and the main transmission line A is coupled with a predetermined coupling amount CD.
A directional coupler 34 for transmitting a signal obtained by attenuating the signal output from the second second output terminal 32b by the coupling amount CD from the main transmission line A to the antenna 5 as a transmission output signal.

[0009] The directional coupler 34 is used by the terminator 3 for signal transmission in the antenna direction on the main transmission line A.
4a, and for signal transmission in the direction of the terminator 34a in the sub transmission line B, the signal is coupled in the antenna direction of the main transmission line A. Note that the minimum value of the attenuation ATT of the attenuator 31 (that is, the maximum value Gmax of the gain) is
0 dB, and the changeable range (dynamic range) of the attenuation ATT is set to be equal to or more than the sum of the gain GA of the power amplifier 33 and the coupling CD of the directional coupler 34 (= GA + CD).

The transmission power control circuit 3 also includes an attenuation control data and a switch 32 for adjusting the attenuation ATT of the attenuator 31 according to a power control signal indicating a target transmission output level from the base station. , A D / A converter 35 for converting the attenuation control data from the microcomputer 100 into an analog signal and outputting the analog signal, and a D / A converter 35. Operational amplifier 3 which amplifies analog signal of the above and outputs it to attenuator 31 as a control voltage
6 and a power supply transistor 37 for supplying a voltage VB of a battery built in the mobile phone to the power amplifier 33 as an operation power supply (bias power supply).

Here, when the switch switching signal from the microcomputer 100 is at a low level, the switch 32 sends the output signal of the attenuator 31 to the first output terminal 32a.
To the main transmission line A, the power transistor 37 is turned on, and the power amplifier 33 is supplied with operating power from the battery. The microcomputer 10
When the switch switching signal from 0 is at a high level, the switch 32 outputs the output signal of the attenuator 31 from the second output terminal 32b to the sub-transmission line B, and the power transistor 37 is turned off. Is shut off.

In the above configuration, the changeover switch 32
Is connected to the first output terminal 32a, the signal obtained by attenuating the input signal by the attenuation ATT of the attenuator 31 is amplified by the gain GA of the power amplifier 33, and the amplified signal is transmitted to the antenna 5 Is supplied as a transmission output signal. When the changeover switch 32 is connected to the second output terminal 32b, a signal obtained by attenuating the input signal by the attenuation ATT of the attenuator 31 is supplied to the sub-transmission line B without passing through the power amplifier 33. The signal is supplied from the main transmission line A to the antenna 5 by the directional coupler 34 as a transmission output signal.

For this reason, as shown in FIG. 10, if the amount of attenuation ATT of the attenuator 31 is minimized while the changeover switch 32 is connected to the first output terminal 32a, the total gain of the transmission power control circuit 3 is reduced. Is maximum and the transmission power (ie,
(The power level of the transmission signal supplied from the main transmission line A to the antenna 5) reaches the maximum level Pmax, and the attenuation ATT of the attenuator 31 is maximized with the changeover switch 32 connected to the second output terminal 32b. In this case, the total gain of the transmission power control circuit 3 becomes the minimum, and the transmission power becomes the minimum level Pmin.

Here, the transmission power level is reduced from the maximum level Pmax by the sum of the gain GA of the power amplifier 33 and the coupling amount CD of the directional coupler 34 from the maximum level Pmax (= Pmax-GA-). 10), the changeover switch 32 is set to the first output terminal 3 as shown on the left side of the black circle “●” in FIG.
The attenuation amount ATT is changed while being connected to the side 2a. In this case, the transmission power is the attenuation ATT of the attenuator 31.
Will change in accordance with

The attenuation ATT of the attenuator 31 is equal to the gain GA of the power amplifier 33 and the coupling CD of the directional coupler 34.
(In other words, the gain of the attenuator 31 becomes smaller than the maximum gain Gmax of 0 dB by the sum of the gain GA of the power amplifier 33 and the coupling amount CD of the directional coupler 34). ), The transmission power is Pmax-GA-C
D, and when the transmission power is further reduced from that level, the switch 32 is switched to the second output terminal 32b side and the attenuator 31 Control is performed so that the attenuation ATT is returned to the minimum value (in other words, the gain of the attenuator 31 is returned to the maximum gain Gmax).

In this manner, the power amplifier 33 is bypassed by the changeover switch 32 and the attenuation is added by the amount of coupling CD of the directional coupler 34. The same power level as immediately before switching to the terminal 32b side (= Pmax-GA-C
D). Then, from this state, if the attenuation ATT of the attenuator 31 is increased (in other words, if the gain of the attenuator 31 is reduced), it is shown on the right side of the black circle “●” in FIG. Thus, the transmission power can be reduced to the minimum level Pmin.

On the contrary, the changeover switch 32 is connected to the second output terminal 3
When the transmission power is increased from Pmin in the state of being connected to the 2b side, the attenuation ATT of the attenuator 31 is reduced. Then, when the attenuation amount ATT becomes the minimum value (in other words, when the gain of the attenuator 31 becomes the maximum gain Gmax), the transmission power becomes Pmax-GA-CD. To further increase the transmission power, the changeover switch 32 is switched to the first output terminal 32a side, and the attenuation ATT of the attenuator 31 is changed by the gain GA of the power amplifier 33 and the coupling amount CD of the directional coupler 34. (In other words, the gain of the attenuator 31 is set to the maximum gain Gma
x is set to a value smaller than 0 dB which is the sum of the gain GA of the power amplifier 33 and the coupling amount CD of the directional coupler 34).
Control.

In this way, the gain GA of the power amplifier 33 is added, and the damping effect of the directional coupler 34 is invalidated. Therefore, the transmission power is the same as that immediately before the changeover switch 32 is switched to the first output terminal 32a. The same power level (= Pmax-GA-CD) results. Then, if the amount of attenuation ATT of the attenuator 31 is reduced from that state, FIG.
At 0, as shown on the left side of the black circle "●",
The transmission power can be increased to the maximum level Pmax.

The operation described above will be described using specific numerical values. For example, the power level of the input signal input to the attenuator 31 is -10 dBm, the variable width of the attenuation ATT of the attenuator 31 is 0 dB to 35 dB (that is, the maximum value Gmax of the gain of the attenuator 31 is 0 dB, and the minimum value is Gmin is -35d
B) Assuming that the gain GA of the power amplifier 33 is 30 dB and the coupling amount CD of the directional coupler 34 is 5 dB, the maximum level Pmax of the transmission power is 20 dBm (= −10 dBm−).
0 dB + 30 dB), and the minimum level Pmin is −50.
dBm (= −10 dBm−35 dB−5 dB).

Then, the transmission power is increased from the maximum level Pmax of 20 dBm to -15 dBm (= Pmax-GA-C
When the change is made to D = 20 dBm-30 dB-5 dB), the changeover switch 32 is set to the first output terminal 32a side to change the attenuation ATT of the attenuator 31. When the attenuation ATT of the attenuator 31 is 35 dB (= GA + CD = 30 dB + 5)
dB), the transmission power becomes -15 dBm. To further reduce the transmission power, the switch 32 is switched to the second output terminal 32b side, and the attenuator 31
Is returned to the minimum value of 0 dB, and the attenuation ATT of the attenuator 31 is changed in this state, the transmission power becomes −
It can be varied from 14 dBm to the minimum level Pmin of -50 dBm.

When the transmission power is changed from the minimum level Pmin of -50 dBm to -15 dBm, the changeover switch 32 is set to the second output terminal 32b to change the attenuation ATT of the attenuator 31. When the attenuation ATT of the attenuator 31 becomes 0 dB which is the minimum value, the transmission power becomes -15 dBm. However, when the transmission power is further increased, the switch 32 is switched to the first output terminal 32a side, and 31 attenuation ATT 35dB
(= GA + CD = 30 dB + 5 dB). If the attenuation ATT of the attenuator 31 is changed in this state, the transmission power becomes-
It can be changed from 15 dBm to the maximum level Pmax of 20 dBm.

The microcomputer 100 controls the transmission power so as to reach the target transmission output level indicating the power control signal from the base station. Therefore, the current transmission power is compared with the target transmission output level, and when it is determined that the transmission power should be reduced, the attenuation ATT of the attenuator 31 is increased by ΔA (for example, 1 dB). When the attenuation ATT of the attenuator 31 becomes 35 dB (= GA + CD), the changeover switch 32 is switched to the second output terminal 32b side, and the attenuation ATT of the attenuator 31 is returned to the minimum value of 0 dB. From the attenuation AT of the attenuator 31
T is increased by ΔA. When it is determined that the transmission power should be increased, the attenuation ATT of the attenuator 31 is determined.
Is decreased by ΔA. Then, the attenuation amount A of the attenuator 31
When the TT reaches the minimum value of 0 dB, the changeover switch 32
Is switched to the first output terminal 32a side, and the attenuation ATT of the attenuator 31 is returned to 35 dB. From this state, the attenuation ATT of the attenuator 31 is decreased by ΔA.

With the above configuration, the transmission power of the transmission power control circuit 3 can be controlled in a wide dynamic range. The present inventor has further studied the transmission power control circuit 3 described above, and has found the following problems. That is, the attenuation ATT of the attenuator 31 is increased, and the attenuation ATT becomes 35d.
B (= GA + CD), the changeover switch 32 is set to the second
While switching to the output terminal 32b side, the attenuation amount ATT of the attenuator 31 is returned to 0 dB which is the minimum value. At this time, the switching timing of the switch 32 and the attenuation amount ATT of the attenuator 31 are returned to 0 dB. If the timing is shifted, the transmission power overshoots or undershoots depending on the time difference. For example, when the attenuation ATT of the attenuator 31 is returned to 0 dB first, and then the switch 32 is switched, the transmission power overshoots as shown in FIG.

The attenuation ATT of the attenuator 31 is reduced, and when the attenuation ATT becomes 0 dB, the changeover switch 32
Is switched to the first output terminal 32a side, and the attenuation ATT of the attenuator 31 is returned to 35 dB. At this time, the switching timing of the changeover switch 32 and the timing of returning the attenuation ATT of the attenuator 31 to 35 dB , A transmission power overshoots or undershoots due to the time difference. For example, the attenuation amount ATT of the attenuator 31 is first set to 35 dB.
Then, when the changeover switch 32 is switched thereafter, the transmission power undershoots as shown in FIG.

In the wideband CDMA system, as shown in FIG. 12, transmission is performed using transmission data having a frame structure composed of pilot symbols and data. When the transmission power overshoots or undershoots, Since the transmission power greatly fluctuates, there arises a problem that transmission data cannot be properly transmitted to the base station. In this case, in the wideband CDMA system, transmission and reception are performed in synchronization with the base station using pilot symbols. Therefore, if pilot symbols cannot be transmitted properly, synchronization performance in communication with the base station is degraded. In addition, when the transmission power overshoots, the transmission power instantaneously increases, causing a problem that the base station becomes an interference wave.

The present invention has been made in view of the above problems, and has as its object to enable transmission power to be controlled in a wide dynamic range and to eliminate overshoot and undershoot of transmission power.

[0027]

In order to achieve the above object, according to the first aspect of the present invention, an output signal of a first variable gain circuit (31) for amplifying an input high-frequency signal is a first signal. Is switched to one of the main transmission line (A) and the sub transmission line (B) by the switching circuit (32) for output. The main transmission line has a second variable gain circuit (38, 4) that amplifies and outputs the output signal of the first variable gain circuit.
2) is provided. When the output signal of the first variable gain circuit is output from the first switching circuit to the main transmission line, the gain of the second variable gain circuit is changed without changing the gain of the first variable gain circuit. When the output signal of the first variable gain circuit is controlled and output from the first switching circuit to the sub-transmission line, the gain of the first variable gain circuit is changed without changing the gain of the second variable gain circuit. Is controlled.

With this, the transmission power can be controlled in a dynamic range obtained by adding at least the gain of the first variable gain circuit and the gain of the second variable gain circuit. Therefore, the transmission power is controlled in a wide dynamic range. be able to. In addition, at the switching timing of the first switching circuit, gain control is performed using one of the first and second variable gain circuits, so that overshoot or undershoot of transmission power does not occur. Can be

As the second variable gain circuit, an attenuator (38) is used as in the second aspect of the present invention.
Alternatively, a variable gain power amplifier (42) that amplifies with a positive gain can be used as in the third aspect of the present invention. Further, according to the present invention as set forth in claim 4, an amplifier (3) for amplifying the main transmission line with a predetermined positive gain.
3) can be provided. In this case, when the first switching circuit switches to output the output signal of the first variable gain circuit from the main transmission line to the sub transmission line as in the invention described in claim 5, the signal to the amplifier is output. Providing the power cutoff means (37) for cutting off the power supply makes it possible to reduce the power consumption of the transmission power control circuit and to prevent the high-frequency signal from leaking to the front stage of the amplifier. Since the power is not amplified and output by the amplifier, the transmission power can be controlled to a low power level.

Further, the directional coupler (3) coupled to the main transmission line with a predetermined coupling amount is provided.
If 4) is provided, the dynamic range can be further widened by the coupling amount of the directional coupler.
In this case, in place of the directional coupler, a second switching circuit (32) for outputting a transmission signal to the antenna from one of the main transmission line and the sub transmission line as in the invention according to claim 7 ) May be provided.

The reference numerals in parentheses indicate the correspondence with specific means described in the embodiments described later.

[0032]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows a configuration of a transmission power control circuit 3 according to one embodiment of the present invention. Those given the same reference numerals as those shown in FIG. 9 indicate that they are the same or equivalent. In this embodiment, the changeover switch 32
, A second attenuator 38 is provided between the first output terminal 32a of the changeover switch 32 and the power amplifier 33, in addition to the attenuator 31 provided in the preceding stage (hereinafter, referred to as the first attenuator 31). D / A from the microcomputer 100
The amount of attenuation of the second attenuator 38 is set by the control voltage amplified by the operational amplifier 40 via the converter 39.

In this embodiment, the control of the first and second amplifiers 31 and 38 and the switching of the changeover switch 32 are performed as follows to control the transmission power. That is, from the maximum level Pmax, Pmax-G
When the transmission power is reduced to A-CD, the changeover switch 32 is connected to the first output terminal 32a, the attenuation ATT1 of the first attenuator 31 is set to the minimum value, The attenuation ATT2 is increased from the minimum value. At this time, the transmission power changes according to the amount of attenuation ATT2 of the second attenuator 38.

Then, the attenuation amount ATT of the second attenuator 38
2 becomes equal to the sum of the gain GA of the power amplifier 33 and the coupling amount CD of the directional coupler 34, the transmission power becomes Pmax−
When the transmission power is further reduced from that level, the changeover switch 32 is set to the second output terminal 32.
Switch to b side. At this time, the attenuation ATT2 of the second attenuator 38 is kept as it is. Thereafter, if the attenuation ATT1 of the first attenuator 31 is increased, the transmission power can be reduced to the minimum level Pmin.

On the contrary, the changeover switch 32 is connected to the second output terminal 3
When the transmission power is increased from Pmin in a state where the transmission power is connected to the side 2b, the attenuation ATT of the first attenuator 31 is used.
Decrease 1 When the attenuation ATT1 of the first attenuator 31 becomes the minimum value, the transmission power becomes Pmax-
GA-CD. To further increase the transmission power, the switch 32 is switched to the first output terminal 32a. At this time, the attenuation amount A of the first attenuator 31
TT1 is left as it is. Thereafter, the second attenuator 3
8, the transmission power can be reduced by reducing the amount of attenuation ATT2.
It can be raised to the maximum level Pmax.

The operation described above will be described using specific numerical values. For example, the power level of the input signal input to the attenuator is -10 dBm, and the variable widths of the attenuation amounts ATT1 and ATT2 of the first and second attenuators 38 are 0 dB to 35 dB (that is, the first and second attenuations). The maximum value Gmax of the gain of the amplifier 38 is 0 dB and the minimum value Gmin is -35 dB).
3, the gain GA is 30 dB, and the coupling amount C of the directional coupler 34 is
Assuming that D is 5 dB, the maximum transmission power level Pma
x is 20 dB (= -10 dBm-0 dB + 30 dB), and the minimum level Pmin is -50 dB (= -10 dBm).
−35 dB−5 dB).

Then, the transmission power is increased from the maximum level Pmax of 20 dBm to -15 dBm (= Pmax-GA-C
D = 20 dBm−30 dB−5 dB), the changeover switch 32 is set to the first output terminal 32 a side,
When the attenuation ATT1 of the first attenuator 31 is set to 0 dB, the second
ATT2 of the attenuator 38 is increased from the minimum value of 0 dB. Then, the attenuation ATT2 of the second attenuator 38 is 35 dB (= GA + CD = 30 dB + 5 dB).
B), the transmission power becomes −15 dBm, but when the transmission power is further reduced, the changeover switch 32 is set to the second position.
Switch to the output terminal 32b side. At this time, the attenuation ATT2 of the second attenuator 38 is kept as it is. Thereafter, if the attenuation ATT1 of the first attenuator 31 is increased from 0 dB, the transmission power can be changed from -15 dBm to -50 dBm, which is the minimum level Pmin.

To change the transmission power from the minimum level Pmin of -50 dBm to -15 dBm, the changeover switch 32 is set to the second output terminal 32b to change the attenuation ATT1 of the first attenuator 31. . When the attenuation ATT1 of the first attenuator 31 becomes 0 dB which is the minimum value, the transmission power becomes -15 dBm. To further increase the transmission power, the switch 32 is switched to the first output terminal 32a. At this time, the attenuation amount ATT1 of the first attenuator 31 is kept as it is. Thereafter, if the attenuation ATT2 of the second attenuator 38 is reduced, the transmission power can be increased to the maximum level Pmax.

FIG. 2 shows the change in transmission power when the transmission power is changed, the state of the changeover switch 32, and the first and second transmission power.
The relationship between the attenuation amounts ATT1 and ATT2 of the attenuator 38 of FIG. Next, transmission power control of the microcomputer 100 for performing the above operation will be described with reference to a flowchart shown in FIG. Microcomputer 10
In step S110, it is determined whether the current transmission power is the target transmission level instructed by the base station. If the current transmission power is the target transmission power level, S
The determination process of step 110 is repeated, but if the current transmission power is not the target transmission output level (S110: NO), S12
Proceeding to 0, it is determined whether the current transmission power should be reduced in order to bring the transmission power to the target transmission output level.

If it is determined in step S120 that the transmission power should be reduced (S120: YES), the process proceeds to step S120.
Proceeding to 130, the changeover switch 32 is switched to the second output terminal 32
It is determined whether or not it is on the b side. And changeover switch 3
2 is not on the second output terminal 32b side (S130: N
O), proceeding to S140, the attenuation amount A of the second attenuator 38
TT2 is the gain GA of the power amplifier 33 and the directional coupler 34.
Is determined to be equal to or greater than -1 dB (= GA + CD-1) with the binding amount CD of the target, otherwise (S140:
NO), at S150, attenuation amount AT of second attenuator 38
After increasing T2 by a predetermined amount ΔA (for example, 1 dB),
It returns to S110.

In S140, the second attenuator 3
When it is determined that the attenuation ATT2 of No. 8 is equal to or more than GA + CD-1 (S140: YES), the process proceeds to S160, where the changeover switch 32 is switched to the second output terminal 32b side, and then returns to S110. Step 13
When it is determined at 0 that the changeover switch 32 is on the second output terminal 32b side (S130: YES), S170
After increasing the attenuation ATT1 of the first attenuator 31 by ΔA, the process returns to S110.

On the other hand, if it is determined in S120 that the transmission power should be increased (S120: NO),
Proceeding to S180, the changeover switch 32 sets the first output terminal 3
It is determined whether it is on the 2a side. If the changeover switch 32 is not on the first output terminal 32a side (S180: N
O), proceeding to S190, the attenuation amount A of the first attenuator 31
It is determined whether or not TT1 has become 0 dB, and if the attenuation ATT1 of the first attenuator 31 has not become 0 dB (S
190: NO), at S200, decrease the attenuation ATT1 of the first attenuator 31 by ΔA, and then return to S110.

In step S190, the first attenuator 3
When it is determined that the attenuation amount ATT1 of 1 has become 0 dB (S190: YES), the process proceeds to S210, and the changeover switch 32 is switched to the first output terminal 32a side.
Return to 110. If it is determined in step 180 that the changeover switch 32 is on the first output terminal 32a side (S180: YES), the process proceeds to S220, and the process proceeds to step S220.
After increasing the attenuation amount ATT2 of the attenuator 38 by ΔA, the process returns to S110.

When the microcomputer 100 executes such transmission power control processing, the transmission power becomes
Automatic control is performed so that the target transmission output level is instructed by the base station. As described in detail above, according to the transmission power control circuit 3 of this embodiment, the first and second attenuators 3
The transmission power can be continuously controlled in a wide dynamic range in which the gain GA of the power amplifier 33 and the coupling amount CD of the directional coupler 34 are added to the dynamic range of 1, 38. Further, at the switching timing of the changeover switch 32, the gain of one of the first and second attenuators 31 and 38 that has been controlled so far is left as it is, and the control is shifted to the gain control by the other attenuator. Thus, overshoot and undershoot of the transmission power can be prevented.

Also, as shown in FIG.
When 2 is switched to the second output terminal 32b side, the power transistor 37 is turned off, and the power supply to the power amplifier 33 is cut off. This allows
The power consumption of the transmission power control circuit 3 can be reduced, and even if a high-frequency signal leaks to a stage preceding the power amplifier 33, the signal is not amplified and output by the power amplifier 33. Therefore, the transmission power can be controlled to a low power level.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can take various forms. For example,
Instead of the directional coupler 34, a changeover switch 41 may be used as shown in FIG. In this case, the first output terminal 41a is connected to the main transmission line A when the switch switching signal from the microcomputer 100 is at a low level, and the second output terminal 41a is connected when the switch switching signal from the microcomputer 100 is at a high level. Terminal 41b is the auxiliary transmission line B
Connected to. In such a configuration, the above-described control is set in a form in which the coupling amount CD of the directional coupler 34 is eliminated.

Also, instead of the second attenuator 38 and the power amplifier 33 shown in FIGS. 1 and 4, as shown in FIG.
A variable gain power amplifier 42 that amplifies with a positive gain according to the control signal of the input signal may be used. The gain of the variable gain power amplifier 42 is controlled by the control voltage amplified by the operational amplifier 44 from the microcomputer 100 via the D / A converter 43. In this case, the microcomputer 100 controls the transmission power as follows.

When the switch 32 is connected to the first output terminal 32a to reduce the transmission power from the maximum level, the gain of the variable gain power amplifier 42 is reduced from the maximum value. And the variable gain power amplifier 4
When the gain of 2 reaches the minimum value of 0 dB, the changeover switch 32
Is switched to the second output terminal 32b side, and the attenuation of the attenuator 31 is increased while the gain of the variable gain power amplifier 42 remains unchanged.

The changeover switch 32 is connected to the second output terminal 2.
When increasing the transmission power from the minimum level by being connected to the b side, the attenuation of the attenuator 1 is reduced. When the amount of attenuation of the attenuator 1 reaches the minimum value of 0 dB, the changeover switch 32 is switched to the first output terminal 32a, and the attenuator 31
The gain of the variable gain power amplifier 42 is increased while the attenuation amount of the variable gain power amplifier 42 remains unchanged.

In this embodiment, the power amplifier 33 may be connected to the variable gain power amplifier 42 in series. Further, in the various embodiments described above, as the first variable gain circuit, in addition to the attenuator 31,
A variable amplifier that amplifies with a positive gain according to the control signal of the input signal may be used. Further, in addition to the attenuators 31 and 38, those whose gain can be changed to both positive and negative may be used as the first and second variable gain circuits.

As the radio, other than the radio shown in FIG. 7, one having the configuration shown in FIG. 6 can be used. In this embodiment, a 2.3 GHz band frequency switching synthesizer 16 is used instead of the 1.95 GHz band frequency switching synthesizer 6 shown in FIG.
A 380 MHz fixed frequency synthesizer 14 is used instead of the z fixed frequency synthesizer 7, and a signal from the 2.3 GHz band frequency switching synthesizer 16 and a signal from the 380 MHz fixed frequency synthesizer 14 are mixed by a frequency mixer 15.
To obtain a signal of 1.92 to 1.98 GHz, which is output to the quadrature modulator 1. Also, 2.3GH
2.3 output from z-band frequency switching synthesizer 16
The frequency mixer 10 performs frequency mixing using a signal of up to 2.36 GHz to obtain a signal of 190 MHz. Also, 3
The 380 MHz signal output from the 80 MHz fixed frequency synthesizer 23 is internally converted to 1
Is input to the quadrature demodulator 13 which divides the frequency by ２.
Performs quadrature demodulation using a 190 MHz signal.

In the case of the configuration shown in FIG. 7, 1.95 GHz
Since the frequency of the signal output from the z-band frequency switching synthesizer 6 and the transmission modulation frequency are the same, 1.9.
The modulated wave has an adverse effect on the 5 GHz band frequency switching synthesizer 6 and the 2.3 GHz band frequency switching synthesizer 24
However, in the case of the configuration shown in FIG. 6, the frequency and the frequency of the signal output from the 2.3 GHz band frequency switching synthesizer 24 are reduced. Since the transmission modulation frequencies are different, deterioration of the modulation accuracy can be minimized.

In the case of the configuration shown in FIG. 7, the frequency of the local signal input to the quadrature demodulator 13 is
Since the same IF signal is input to the quadrature demodulator 13 via the F amplifier 11 and the 190 MHz band limiting filter 12, unnecessary DC components are added to the I and Q signals after quadrature demodulation by the quadrature demodulator 13. However, the influence of the DC component multiplication can be minimized by setting the frequency of the local signal input to the quadrature demodulator 13 to 380 MHz as shown in FIG. .

The transmission power control circuit 3 according to the present invention
Can also be used for other wireless communication devices other than mobile phones.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a transmission power control circuit according to an embodiment of the present invention.

FIG. 2 shows the configuration of FIG. 1 in which the transmission power changes when the transmission power is changed, the state of the changeover switch 32, and the attenuation amounts ATT1, ATT of the first and second attenuators 38.
FIG. 2 is a diagram illustrating a relationship of FIG.

FIG. 3 is a flowchart showing a transmission power control process of the microcomputer 100 in FIG. 1;

FIG. 4 shows a directional coupler 34 for the embodiment shown in FIG.
FIG. 11 is a diagram showing an embodiment using a changeover switch 41 in place of FIG.

FIG. 5 differs from the embodiment shown in FIGS. 1 and 4 in that a variable gain power amplifier 4 is used instead of the second attenuator 38 and the power amplifier 33.
FIG. 3 is a diagram showing an embodiment using No. 2;

FIG. 6 is a diagram illustrating a configuration of a wireless device.

FIG. 7 is a diagram illustrating a configuration of a wireless device.

FIG. 8 is a diagram for explaining a conventional transmission power control circuit configuration.

FIG. 9 is a diagram showing a configuration of a transmission power control circuit previously proposed by the present applicant.

FIG. 10 is a diagram provided for describing an operation of the transmission power control circuit illustrated in FIG. 9;

FIG. 11 is a diagram for explaining a problem of the transmission power control circuit shown in FIG. 9;

FIG. 12 is a diagram showing a configuration of transmission data.

[Explanation of symbols]

3: transmission power control circuit, 31: first attenuator, 32, 4
DESCRIPTION OF SYMBOLS 1 ... Changeover switch, 33 ... Power amplifier, 34 ... Directional coupler, 35, 39 ... D / A converter, 36, 40 ... Operational amplifier, 38 ... Second attenuator, 42 ... Variable gain power amplifier, 100 ... a microcomputer.

Claims (7)

[Claims] A first variable gain circuit that amplifies an input high-frequency signal with a gain that changes according to a control signal and outputs the amplified signal, and a main transmission circuit that outputs an output signal of the first variable gain circuit. Track (A)
And a first switching circuit (32) for switching to one of the sub transmission line (B) and outputting the signal, and an output signal of the first variable gain circuit provided on the main transmission line in accordance with a control signal. A second variable gain circuit (38, 42) for amplifying and outputting the gain by changing the gain, wherein an output signal of the first variable gain circuit is output from the first switching circuit to the main transmission line. The gain of the second variable gain circuit is controlled without changing the gain of the first variable gain circuit, and the output signal of the first variable gain circuit is output from the first switching circuit through the first switching circuit. Transmission power control wherein the gain of the first variable gain circuit is controlled without changing the gain of the second variable gain circuit when the signal is output to a sub-transmission line. apparatus. 2. The attenuator (3), wherein the second variable gain circuit includes an attenuator (3).
The transmission power control circuit according to claim 1, wherein 8). 3. The transmission power control circuit according to claim 1, wherein said second variable gain circuit is a variable gain power amplifier for amplifying with a positive gain. 4. The transmission according to claim 1, wherein the main transmission line is provided with an amplifier for performing amplification with a predetermined positive gain. Power control circuit. 5. The power supply to the amplifier is shut off when the first switching circuit switches the output signal of the first variable gain circuit to output from the main transmission line to the sub transmission line. 5. The transmission power control circuit according to claim 4, further comprising a power cut-off means (37) for turning off the power. 6. A signal coupled to the main transmission line with a predetermined coupling amount and attenuated by the coupling amount with respect to an output signal of the first variable gain circuit output to the sub transmission line,
The transmission power control circuit according to any one of claims 1 to 5, further comprising a directional coupler (34) for transmitting the signal from the main transmission line to the antenna. 7. A switching circuit (32) for outputting a transmission signal from one of the main transmission line and the sub transmission line to an antenna.
The transmission power control circuit according to any one of the above.