JP2954024B2 - Transmission power control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a transmission power control circuit, and more particularly to a transmission power control circuit having improved automatic power control characteristics over a wide dynamic range of transmission power.

[0002]

2. Description of the Related Art As shown in Japanese Patent Application Laid-Open No. 4-100426, automatic transmission power control is conventionally performed in a radio transmitter. FIG. 4 shows an example of a transmission power control circuit in a wireless transmitter for this purpose. The transmission power control circuit of FIG.
An amplifying unit 1 with a variable gain function that amplifies by a gain that changes in accordance with the value of 6 and outputs it as a high-frequency signal 37;
A splitter 2 that splits an input high-frequency signal 37 into a transmission output signal 38 and a detection output signal 39 and outputs each of them.
A detection unit 3 which receives and detects the detection output signal 39 and outputs a detection voltage 40 corresponding to the magnitude of the power level of the transmission output signal 38 of the wireless transmitter; and a detection voltage 40 from the detection unit 3. Compare with the control voltage 31 that determines the transmission power,
An amplifier control voltage generator 4 supplies an error voltage between the control voltage 31 and the detection voltage 40 to the amplifier 1 as a control voltage 36 for the amplifier 1.

Next, the operation will be described.

[0004] The high-frequency signal 21 input to the radio transmitter
Is amplified by the amplifying unit 1 with a gain that changes in accordance with the value of the control voltage 36, and transmitted through the distributor 2 to the transmission output signal 38.
Is output as The distributor 2 supplies a detection output signal 39 extracted for detection from the input high-frequency signal 37 to the detection unit 3. The detector 3 outputs a detection voltage 40 indicating a voltage value corresponding to the output level of the transmission power to the amplifier control voltage generator 4. The amplification unit control voltage generation unit 4 compares the detection voltage 40 from the detection unit 3 with an external control voltage 31 indicating a value that determines the output level of the transmission power, and calculates an error voltage between the detection voltage 40 and the control voltage 31. The control voltage 36
And outputs the result to the amplifier 1. That is, a negative feedback loop is formed, and the output level of the transmission power is kept constant as a target value by the negative feedback loop, as the output level of the transmission power corresponding to the control voltage 31 given from the outside. Is controlled.

As the above-mentioned detector 3, a detector composed of a simple detector circuit using a generally well-known diode is used. One example of the characteristics of this detector is shown in FIG. . In this detector, the power level is +10
Although it is possible to detect the output level of the transmission power within the range of about dBm to −20 dBm, the detector cannot detect the output level of the transmission power accurately outside the above range. The dynamic range indicating the range is about 30 dB as described above. The detector described above is also used as the detector used in the detector 3 shown in FIG. Also, the dynamic range of the transmission power of the transmitter controlled by the transmission power control circuit shown in FIG. 4 using the detection unit 3 is about 30 dB, which is the same as the dynamic range of the detection unit 3.

Therefore, in order to output the dynamic range of the transmission power of the transmitter controlled by the transmission power control circuit shown in FIG. 4 wider and more accurately, the same dynamic range as the target dynamic range of the transmission power is required. It is necessary to perform detection by the detection unit 3 having a range. However, as described above, in the conventional detection unit 3, the dynamic range of the output level of the transmission power can be obtained only about 30 dBm, and there is a minimum detectable power. Cannot be detected, so that a plurality of detectors having different power level ranges that can be detected are provided, and the detectors are switched and operated according to the output level of the transmission power, or the detector 3
For example, a method of providing a plurality of amplifiers for raising the level of the detection output signal 39 supplied to the power supply and switching the connection of the amplifiers according to the output level of the transmission power to operate the amplifier is performed.

[0007]

SUMMARY OF THE INVENTION In the radio transmitter having the above-mentioned conventional transmission power control circuit, in order to widen the dynamic range of the output level of the transmission power in the transmission power control, the detector of the transmission power control circuit is required. It is necessary to expand the dynamic range of the output level of the transmit power that can be detected, and furthermore, a plurality of detectors or a plurality of amplifiers for amplifying the power to be detected are provided to expand the dynamic range of the detector. Has to be switched according to the

An object of the present invention is to provide a transmission power control circuit capable of expanding a dynamic range of an output level without providing a plurality of detectors or a plurality of amplifiers for amplifying detected power. is there.

[0009]

A transmission power control circuit according to the present invention amplifies an input first high-frequency signal by an amplifier having a gain that changes in accordance with a value of a first control voltage. 2, the second high-frequency signal is divided into a third high-frequency signal and a fourth high-frequency signal, the fourth high-frequency signal obtained is detected, and the level of the third high-frequency signal is detected. , A first control voltage is generated from the detection voltage and the second control voltage, the third high-frequency signal is branched into a plurality of high-frequency signals, and the first control voltage is branched. The plurality of high-frequency signals are given a loss so as to become high-frequency signals having different levels stepwise at predetermined intervals, and any one of the branched high-frequency signals is selected from among the plurality of branched high-frequency signals according to a switch switching control signal. High-frequency signal Output as an output signal, wherein the second control voltage and the switch switching control signal are generated from a control voltage which is an externally supplied instruction signal for setting a power level of the transmission output signal to a target level. It is configured as follows.

Further, the transmission power control circuit of the present invention comprises:
(A) amplifying means for amplifying the input first high-frequency signal and outputting it as a second high-frequency signal with a gain that changes in accordance with the given value of the first control voltage; Distributing means for distributing the high-frequency signal into a third high-frequency signal and a fourth high-frequency signal and outputting each of them; (C) inputting and detecting the fourth high-frequency signal and detecting the level of the third high-frequency signal; (D) first control voltage generation means for inputting a second control voltage and the detection voltage and outputting the first control voltage to the amplification means, (E) The third high-frequency signal is input and branched into a plurality of high-frequency signals, and the plurality of branched high-frequency signals become high-frequency signals having different levels stepwise at fixed intervals. Signal branching means for giving a loss and outputting the signal, (F) A plurality of branched high-frequency signals output from the signal branching unit are input, and one of the input high-frequency signals is selected as a transmission output signal according to an instruction of a switch switching control signal. (G) control means for receiving a control voltage which is an instruction signal for setting a power level of the transmission output signal to a target level, and outputting the switch switching control signal and the second control voltage , Is configured.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings.

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

The transmission power control circuit of the present embodiment shown in FIG. 1 amplifies an input high-frequency signal 21 with a gain that changes in accordance with the value of
, An amplifier 2 that divides the high-frequency signal 23 output from the amplifier 1 into a high-frequency signal 25 and a detection output signal 26, and outputs the high-frequency signal 25 and the detection output signal 26, respectively. The detection unit 3 that outputs a detection voltage 24 corresponding to the level of the high-frequency signal 25 and the control voltage 33 and the detection voltage 24 from the detection unit 3 are input, and the control voltage 22 is output to the amplification unit 1. Amplifier control voltage generator 4
And three high-frequency signals 27 and 2 whose output levels are changed stepwise with the high-frequency signal 25 output from the distributor 2 as an input.
8 and 29, and high-frequency signals 27, 28 and 29 of different levels output by the signal branching unit 5.
And a switch section 6 for selecting any one of the high-frequency signals from the high-frequency signals in accordance with the instruction of the switching control signal 32 and outputting the selected signal as a transmission output signal 30; Control voltage 33
And a control unit 7 for outputting the same.

In FIG. 1, a high-frequency signal 25 branches into three high-frequency signals 27, 28 and 29 whose levels are suppressed stepwise by the signal branching unit 5. These three high-frequency signals 27, 28, 29 are set at different levels. For example, the level of the high frequency signal 28 is suppressed by 60 dB from the level of the high frequency signal 25,
9 has its level suppressed by 30 dB from the level of the high frequency signal 25. The high-frequency signal 27 is set at the same level as the high-frequency signal 25 without suppressing the level. Here, the signal branching unit 5 is realized by a directional coupler composed of a coupled stripline including a main line 51 and branch lines 52 and 53. The main line 51 outputs the high-frequency signal 27, the branch line 52 outputs the high-frequency signal 28, and the branch line 53 outputs the high-frequency signal 29. The branch lines 52 and 53
Is a circuit that is coupled to the main line 51 at high frequencies, and is not necessarily a strip line.

The high frequency signals 27, 28 and 29 are supplied to common terminals 61, 62 and 63 of the switch section 6, respectively. The switch unit 6 performs three types of switch connection according to the switching control signal 32 supplied from the control unit 7.
That is, the first is a connection between the common terminal 61 and the switching terminal 64, the connection between the common terminal 62 and the switching terminal 67, and the switch connection for simultaneously connecting the common terminal 63 and the switching terminal 70. Connection with the switching terminal 65,
A connection for simultaneously connecting the common terminal 62 and the switching terminal 68, and a connection for simultaneously connecting the common terminal 63 and the switching terminal 71, and a third connection between the common terminal 61 and the switching terminal 66, and a connection between the common terminal 62 and the switching terminal 69. And the connection between the common terminal 63 and the switching terminal 72 at the same time. In the above three types of connections, three switches are respectively linked to perform switching connection simultaneously. For example, in the first switch connection, the common terminal 61 and the switching terminal 64 of the switching unit 6, the common terminal 62 and the switching terminal 67, and the common terminal 6
3 and the switching terminal 70 are connected to each other, so that the switching terminals 67 and 70 are respectively connected to the terminating resistors, and only the high-frequency signal 27 is selected and output. Next, in the second switch connection, the switching terminals 65 and 71 are similarly connected to the terminating resistors, and only the high-frequency signal 28 is selected and output. Finally, in the third switch connection, the switching terminals 66 and 69 are respectively connected to the terminating resistors, and only the high-frequency signal 29 is selected and output.

Next, the operation will be described.

For example, the maximum output power of the amplification unit 1 is set to +13
dBm, the distribution loss of the distributor 2 is -3 dB, and the amplification unit 1
The variable width of the power control is 0 to -30 dB. The dynamic range of power level detection in the detection unit 3 is 30 dB, and the detectable power level range is +10.
It is assumed that the range from dBm to -20 dBm is possible. Under such conditions, when operating the transmission output signal 30 of the transmission power control circuit so that the transmission output signal 30 has a target level within a range of +10 dBm to −20 dBm, the control unit 7
A switching control signal 32 is output to the switch unit 6 to control switching so that the switch unit 6 selects and outputs the high-frequency signal 27, and a control voltage 33 for controlling the gain of the amplifier unit 1 is generated by the amplifier unit control voltage generation. Output to unit 4 and amplify unit 1
Output power level of the high frequency signal 23 is +13 dBm
The power control is performed so as to maintain the target level within the range of -17 dBm. The high-frequency signal 23 output from the amplifying unit 1 is maintained at a target level within a range of +13 dBm to −17 dBm, passes through the distributor 2, and passes through the distributor 2.
Signal 2 whose level is reduced by 3 dB due to the loss inside
5 is input to the signal branching unit 5. The high-frequency signal 25 input to the signal branching unit 5 is output as the high-frequency signal 27 through the main line 51 and is output from the transmission power control circuit as the transmission output signal 30 through the common terminal 61 and the switching terminal 64 of the switch unit 6. You. The high frequency signal 27 is the high frequency signal 2
Since the transmission output signal 30 is at the same level as 5, the power level of the transmission output signal 30 that is 3 dB lower than the high-frequency signal 23 output from the amplifier 1 is maintained at the target level within the range of +10 dBm to −20 dBm. The output power of the transmission power control at this time is expressed by the following equation.

Output power of the transmission power control circuit = output level of the amplifying unit 1 (+13 to -17 dBm) + loss due to distribution in the distributor 2 (-3 dB) + suppression amount by the signal branching unit 6 (0 dB) = + 10 That is, in the above case, the output power of the transmission power is +1
It is in the range of 0 to -20 dBm.

Next, the transmission output signal 3 of the transmission power control circuit
In the case where the operation is performed so that the level of 0 becomes a target level within the range of −20 dBm to −50 dBm, the control unit 7
Outputs the switching control signal 32 to the switch unit 6, controls the switching so that the switch unit 6 selects and outputs the high-frequency signal 29, and controls the gain of the amplifier unit 1 as in the above case. The control voltage 33 is output to the amplifier control voltage generator 4 so that the power control is performed so that the power level of the high-frequency signal 23 output from the amplifier 1 is maintained at a target level within a range of +13 dBm to −17 dBm. Do. The high-frequency signal 23 output from the amplifying unit 1 is +13 dBm or higher.
The signal is maintained at the target level within the range of −17 dBm, passes through the distributor 2, and receives a loss in the distributor 2 so that the level becomes 3.
The signal is input to the signal branching unit 5 as a high-frequency signal 25 whose dB has been reduced. The high-frequency signal 25 input to the signal branching unit 5 is
The signal is output as the high-frequency signal 29 through the branch line 53 and is output from the transmission power control circuit as the transmission output signal 30 through the common terminal 63 and the switching terminal 72 of the switch section 6. Since the high-frequency signal 29 has a level lower than the high-frequency signal 25 by 30 dB, the power level of the transmission output signal 30 is (3 + 30) higher than the high-frequency signal 23 output from the amplifier 1.
It is maintained at the target level in the range of -20 dBm to -50 dBm, which is a dB lower level. The output power of the transmission power control at this time is expressed by the following equation.

Output power of the transmission power control circuit = output level of the amplifier 1 (+13 to -17 dBm) + loss due to distribution in the distributor 2 (-3 dB) + amount of suppression (-30 dB) by the signal branching unit 6 = -20 to -50 dBm That is, in the above case, the output power of the transmission power is -2.
The range is from 0 to -50 dBm.

Finally, when the transmission power control circuit is operated so that the level of the transmission output signal 30 becomes a target level within the range of -50 dBm to -80 dBm, the control unit 7 switches the switch unit 6 The control signal 32 is output to control the switching so that the switch unit 6 selects and outputs the high-frequency signal 28, and the control voltage 33 for controlling the gain of the amplifying unit 1 is controlled by the amplifying unit control in the same manner as described above. High-frequency signal 23 output to voltage generator 4 and output from amplifier 1
The power control is performed so that the power level is maintained at the target level within the range of +13 dBm to -17 dBm.
The high frequency signal 23 output from the amplifier 1 is +13 dBm
The signal is maintained at a target level within the range of -17 dBm, passes through the distributor 2, and is input to the signal branching unit 5 as a high-frequency signal 25 whose level has been reduced by 3 dB due to loss in the distributor 2. High frequency signal 25 input to signal branching unit 5
Is output as the high-frequency signal 28 through the branch line 52 and is output from the transmission power control circuit as the transmission output signal 30 through the common terminal 62 and the switching terminal 68 of the switch unit 6. Since the high-frequency signal 28 is at a level 60 dB lower than the high-frequency signal 25, the power level of the transmission output signal 30 is
From the high-frequency signal 23 output from the amplifier 1 (3 + 6
0) A low level of -50 dBm to -80 dBm
Is maintained at the desired level within the range. The output power of the transmission power control at this time is expressed by the following equation.

Output power of the transmission power control circuit = output level of the amplifier 1 (+13 to -17 dBm) + loss due to distribution in the distributor 2 (-3 dB) + amount of suppression by the signal branching unit 6 (-60 dB) = -50 to -80 dBm That is, in the above case, the output power of the transmission power is -5
The range is from 0 to -80 dBm.

As described above, the set value of the output level of the transmission power control circuit shown in FIG.
The switch unit 6 is controlled by the switching control signal 32 output from the control unit 7 to switch the corresponding switch of the switch unit 6 depending on which of the three stages, 20 to -50 dBm and -50 to -80 dBm, By supplying the control voltage 33 to the amplification unit control voltage generation unit 4 and controlling the gain of the amplification unit 1, even if the dynamic range of the detection unit 3 is the same as the conventional 30 dB, the dynamic range of the power level is detected as the transmission output. The dynamic range can be expanded to three times the dynamic range of part 3.
Accurate transmission power control can be performed. FIG. 2 shows the relationship between the output level, the level of the power supplied to the detection unit 3, the amount of suppression of the level by the signal branching unit 5, and the like in the above description. FIG. 3 shows the detection characteristics at this time.

[0024]

As described above, according to the transmission power control circuit of the present invention, a high-frequency signal is input to the output side of the high-frequency signal distributor of the conventional transmission power control circuit and branched into a plurality of high-frequency signals. A signal branching means for giving a loss so that the plurality of branched high-frequency signals become high-frequency signals having different levels stepwise at regular intervals, and outputting the plurality of high-frequency signals output from the signal branching means; And a switch switching means for selecting any one of the high-frequency signals from a plurality of input high-frequency signals according to an instruction of the switch switching control signal and outputting the selected signal as a transmission output signal, and further outputting the switch switching control signal. Means for outputting the switch switching control signal from the control means, and using the amplifying section in accordance with the switching operation of the output signal by the switch switching means. By which is adapted to output a control voltage for changing the, without providing a plurality of amplifiers for amplifying the power of a plurality of detectors or detector,
This has the effect that the dynamic range of the output level can be expanded.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining an operation of the transmission power control circuit of FIG. 1;

FIG. 3 is an explanatory diagram illustrating an example of a detection characteristic of the transmission power control circuit of FIG. 1;

FIG. 4 is a block diagram showing a conventional transmission power control circuit.

FIG. 5 is an explanatory diagram showing detection characteristics of the transmission power control circuit of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Amplification part 2 Divider 3 Detection part 4 Amplification part control voltage generation part 5 Signal branch part 6 Switch part 7 Control part 51 Main line 52, 53 Branch line

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 1/04

Claims (2)

(57) [Claims] An amplifier having a gain that varies according to a value of a first control voltage amplifies an input first high-frequency signal into a second high-frequency signal, and converts the second high-frequency signal into a second high-frequency signal. The fourth high-frequency signal obtained by distributing the third high-frequency signal and the fourth high-frequency signal is detected and the third high-frequency signal is detected.
A detection voltage corresponding to the magnitude of the level of the high-frequency signal, generating the first control voltage from the detection voltage and the second control voltage, and branching the third high-frequency signal into a plurality of high-frequency signals Then, the plurality of branched high-frequency signals are given a loss so as to become high-frequency signals having different levels stepwise at predetermined intervals, and a switch switching control signal is output from the plurality of branched high-frequency signals. Select one of the high-frequency signals according to the instruction of and output it as a transmission output signal,
The transmission wherein the second control voltage and the switch switching control signal are generated from a control voltage which is an instruction signal for setting a power level of the transmission output signal to a target level, which is provided from outside. Power control circuit. (A) Amplifying means for amplifying an input first high-frequency signal and outputting as a second high-frequency signal with a gain that changes according to a value of a given first control voltage; B) distribution means for distributing the second high-frequency signal into a third high-frequency signal and a fourth high-frequency signal and outputting each of them; and (C) inputting and detecting the fourth high-frequency signal to perform the third high-frequency signal. (D) a first detecting means for inputting a second control voltage and the detected voltage and outputting the first control voltage to the amplifying means; Control voltage generating means, (E) receiving the third high-frequency signal and branching the plurality of high-frequency signals into a plurality of high-frequency signals; A signal branch that gives a loss so that it becomes a signal and outputs it (F) inputting a plurality of branched high-frequency signals output from the signal branching unit, and selecting any high-frequency signal from the input plurality of high-frequency signals in accordance with an instruction of a switch switching control signal; Switch switching means for outputting as a transmission output signal; (G) receiving a control voltage which is an instruction signal for setting a power level of the transmission output signal to a target level, the switch switching control signal and the second control voltage A transmission power control circuit, comprising: