JP3017012B2 - Test equipment for amplification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test for performing an test or evaluation by simultaneously supplying a plurality of frequency components to an amplifying apparatus for simultaneously amplifying n-wave (n; an integer of 2 or more) frequency components. Related to the device.

[0002]

2. Description of the Related Art For example, in a mobile communication base station apparatus, a method of simultaneously amplifying a plurality of carriers such as eight, sixteen and twenty-four waves is used. FIG. 7 shows an outline of a system using such a method.

The system shown in FIG.
., 10-n, a combining circuit 12, an amplifying device 14, and a communication antenna 16. Oscillation circuit 1
.., 10-n oscillate at predetermined frequencies f ₁ , f ₂ ,..., F _n , respectively, and their oscillation outputs are combined by the combining circuit 12. The combining circuit 12 provides the combined output to the amplifying device 14, which amplifies the signal and transmits the amplified signal from the transmitting antenna 16. Thus, in the system shown in FIG. 7, the frequencies f ₁ ,
The carriers of f ₂ ,..., f _n are synthesized and simultaneously amplified by the amplifier 14.

[0004] Such a system, especially its amplifying device 1
In order to perform the performance evaluation of No. 4, a test apparatus equipped with a signal source that simultaneously generates a large number of carriers is required. FIG.
1 shows a configuration of a test apparatus according to a conventional example.

The test apparatus 18 shown in FIG. 1 includes a reference oscillation circuit 20, oscillation circuits 22-1, 22-2,.
And a synthesizing circuit 24. The reference oscillation circuit 20
For example, each oscillation circuit 22 configured as a PLL circuit
An oscillation output having a predetermined reference frequency is given to 1, 22-2,. Each oscillation circuit 22-1, 22-
2,..., 22-n use the oscillation output of the reference oscillation circuit 20 as the reference for the frequency and the phase, respectively, and determine the predetermined frequency f ₁ ,
Oscillate at f ₂ ,. Although not shown in this figure, the division ratio of the reference frequency in each of the oscillation circuits 22-1, 22-2,..., 22-n is set to a predetermined value by the control circuit. The synthesis circuit 24 includes the oscillation circuits 22-1, 22-2,
... synthesize the oscillation outputs of 22-n and supply them to the amplifier 14 to be tested.

As described above, when the test apparatus 18 is configured as a PLL synthesizer, only one reference oscillation circuit 20 is required, and the apparatus configuration is simplified.

[0007]

However, in the conventional test apparatus having such a configuration, the reference of the oscillation frequency and the phase of each oscillation circuit is given by a single reference oscillation circuit. The phase relation of the oscillation output of the circuit was strong. Therefore, the overlap of the peaks,
It is said that phenomena such as cancellation of peaks due to the output phase of each oscillation circuit being out of phase occur periodically, and as a result, the peak power of the signal supplied to the amplifier to be tested significantly fluctuates. A problem had arisen.

For example, as shown in FIG. 9, when the peak of the oscillation output of each oscillation circuit overlaps, the peak power of the signal output from the synthesis circuit increases. Conversely, as shown in FIG. 10, when the oscillation output of each oscillation circuit is in the opposite phase, the peak power of the signal output from the synthesis circuit decreases. However, the average power of the output signal of the combining circuit does not change.

On the other hand, characteristics such as the amount of intermodulation distortion attenuation of an amplifying element, for example, a transistor constituting an amplifying apparatus to be tested largely depend on the peak power of an input signal. Therefore, when the peak power of the signal source used in the test apparatus fluctuates greatly, it becomes difficult to evaluate the performance of the amplifier with good reproducibility and high accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and more precisely suppresses fluctuations in the peak power of a signal supplied to an amplification device to be tested, thereby achieving more accurate amplification. An object of the present invention is to enable performance evaluation of a device.

[0011]

In order to achieve the above object, a test apparatus according to the present invention comprises a plurality of oscillating circuits which oscillate at different frequencies while using the oscillating output of a reference oscillating circuit as its oscillation phase reference. Means for giving different phase fluctuations to the output of

A test apparatus according to a second aspect of the present invention is characterized in that the test apparatus has a modulation circuit for applying a random phase or frequency modulation to the oscillation outputs of the plurality of oscillation circuits as phase fluctuation means.

According to a third aspect of the present invention, in the test apparatus, the plurality of oscillation circuits oscillate at different frequencies by dividing the oscillation output of the reference oscillation circuit by different division ratios. However, the present invention is characterized by including a control means for giving a fluctuation to the frequency division ratio of the plurality of oscillation circuits.

A test apparatus according to a fourth aspect of the present invention is characterized in that the control means of the third aspect sets the frequency division ratio using a pseudo noise (PN) code.

A test apparatus according to a fifth aspect of the present invention is characterized in that the phase fluctuation means includes a plurality of modulation circuits for respectively applying random phase or frequency modulation to the oscillation output of the reference oscillation circuit.

The test apparatus according to claim 6 of the present invention is characterized in that the modulation circuit according to claim 2 or 5 is a modulation circuit using a pseudo noise code as a signal source.

[0017]

In the present invention, the oscillation output of the reference oscillation circuit is provided to each oscillation circuit, and each oscillation circuit oscillates while using the oscillation output of the reference oscillation circuit as a reference for the oscillation phase. The oscillation output of each oscillation circuit is synthesized by a synthesis circuit and supplied to an amplifier to be tested. At this time, different phase fluctuations are given to the oscillation output phase of each oscillation circuit. This phase fluctuation is achieved by a method in which a random phase or frequency modulation is applied to the output of each oscillation circuit in claim 2, and by a method in which the frequency division ratio of each oscillation circuit fluctuates in claim 3. In the above method, a random phase or frequency modulation is applied to the oscillation output of the reference oscillation circuit and supplied to each oscillation circuit. In particular, in claim 4, the fluctuation of the dividing ratio in claim 3 is given by setting using a PN code, and in claim 6, a PN modulation circuit using a pseudo noise code as a signal source is used as a modulation circuit. . If the oscillation output phase of each oscillation circuit fluctuates in this way, the phase relationship will be lost, resulting in an increase in peak power due to periodically overlapping peaks and a decrease in peak power due to the addition of antiphase. Therefore, the characteristic and capability of the intermodulation distortion attenuation of the amplifier can be accurately evaluated.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The same components as those in the conventional example shown in FIG.

FIG. 1 shows a configuration of a test apparatus according to a first embodiment of the present invention. The test apparatus 26 shown in this figure has a configuration in which n PN modulation circuits 28-1, 28-2... 28-n are further added to the conventional example shown in FIG. Each of the PN modulation circuits 28-1, 28-2,.
Are provided corresponding to the oscillation circuits 22-1, 22-2,..., 22-n, respectively.
2... 22-n are supplied to the synthesizing circuit 24 after being modulated by the PN code. PN modulation circuits 28-1 and 28
-2 ... of the PN signal for use in PN modulated in 28-n pattern is set to a different Ru pattern respectively, also phase modulation significant frequency _{f 1, f} 2 ... _{f n} are applied by the PN pattern Should be small enough not to fluctuate. 2 to 4 show the effect of this embodiment. FIG. 2 shows an example of the configuration of the amplifier 14 to be tested, and FIGS. 3 and 4 show output spectra of the amplifier 14 in the present embodiment and the conventional example, respectively.

First, the amplifying device 14 shown in FIG. 2 is a non-linear distortion compensation feedforward amplifier, and includes a distortion detection loop 30 and a distortion removal loop 32 as a feedforward loop. First, in the distortion detection loop 30, the input signal is distributed to the main amplifier 36 and the directional coupler 38 by the distributor 34, and the input signal amplified by the main amplifier 36 is further supplied to the directional coupler 38.
The control circuit 40 controls the output of the main amplifier 36 and the output from the distributor 34 to the directional coupler 38 to have an inverse homologous amplitude.
The gain and phase of the main amplifier 36 are controlled. Main amplifier 36
Supplied to the directional coupler 38 from the main amplifier 3
The signal supplied to the directional coupler 38 directly from the distributor 34 is a signal that does not include such distortion. The directional coupler 38 outputs a signal containing distortion to the distortion removal loop 32, while subtracting a signal containing no distortion from the signal containing distortion and supplies the resulting signal to the auxiliary amplifier 41 of the distortion removal loop 32. The auxiliary amplifier 41 amplifies the distortion component obtained as a result of the subtraction under the control of the gain and phase of the control circuit 40, and supplies the resultant to the directional coupler 42. The directional coupler 42 subtracts the output signal of the auxiliary amplifier 41 from the signal supplied directly from the directional coupler 38, and outputs a signal from which distortion has been removed.

When a signal whose peak power periodically fluctuates greatly is supplied to such an amplifying device 14 as in the prior art, if the peaks of the respective signals overlap, the peak power increases and the load on the amplifying device 14 is reduced. Heavier. At this time,
As shown in FIG. 4, the output signal of the amplifier 14
Spectra due to intermodulation distortion appear above and below the carrier. When the peaks of the signals overlap and the peak power is reduced, the load on the amplifier 14 is reduced, and no spectrum due to intermodulation distortion appears in the output signal (not shown).

On the other hand, when the PN modulation is applied to the oscillation output of each of the oscillation circuits 22-1, 22-2... 22-n as in the present embodiment, as shown in FIG. Is suppressed to be low, and the original performance of the amplification device 14 can be accurately measured. In other words, in this embodiment, since the output of each of the oscillation circuits 22-1, 22-2... 22-n is subjected to phase modulation by the PN modulation circuits 28-1, 28-2. The possibility that the peaks of a large number of carriers synthesized by the synthesis circuit 24 overlap or cancel each other is very low, and the amplification device 14
In addition, it is possible to perform more accurate and accurate performance evaluation of a base station apparatus including the same. Specifically, reproducibility of 1 dB or less is provided. In addition, since a single reference oscillation circuit 20 for providing a reference frequency is sufficient, the device configuration is simple and the cost can be reduced. Since the phase modulation by the PN pattern is slight, it hardly affects the evaluation.

FIG. 5 shows the configuration of a test apparatus 44 according to a second embodiment of the present invention. This diagram is a diagram showing the control circuit 46 omitted in FIG. The control circuit 46 is a circuit that sets the frequency division ratio in the oscillation circuits 22-1, 22-2,.

This embodiment is characterized in that phase fluctuations are given to the oscillation output phases of the oscillation circuits 22-1, 22-2... 22-n by setting the frequency division ratio. That is, the control circuit 46 controls each oscillation circuit 22-1,
By giving a fluctuation to the frequency division ratio of a frequency divider (not shown) constituting 22-2.
1, 22-2... 22-n are given phase fluctuations. The fluctuation of the frequency division ratio is given by the control circuit 46 setting the frequency division ratio in each frequency divider using different PN codes. With such a circuit configuration, the same effects as in the first embodiment can be obtained. In addition, in the case of this embodiment, it is sufficient to change the software of the control circuit 46 from that of the conventional example.

FIG. 6 shows a configuration of a test apparatus 48 according to a third embodiment of the present invention. In this embodiment, the PN modulation circuits 28-1, 28-2,..., 28-n are arranged before the oscillation circuits 22-1, 22-2,. The PN modulation circuits 28-1, 28-2,.
The oscillating output of the reference oscillating circuit 20 is subjected to PN modulation with different PN patterns, and the corresponding oscillating circuit 22-1,
22-2,... 22-n. In this embodiment, the same effects as in the first embodiment can be obtained.

In the above description, the amplifying device in the mobile communication base station device has been subjected to the test or evaluation, but may be replaced with an amplifying device for another use. For example, the present invention is applicable to any system that generates and amplifies a plurality of carriers simultaneously, such as multicarrier transmission using an optical fiber, a CATV, and a digital MCA base station. In addition, the carrier is n waves, but this may be any n, such as 8, 16, or 24 waves. Furthermore, the frequency of the carrier is not limited,
For example, frequencies in the VHF and UHF bands can be used as carriers. In addition, there is no limitation on the means for giving the phase fluctuation. When phase fluctuation is performed by frequency or phase modulation, a modulation method other than PN modulation can be used. The test target is not limited to the configuration shown in FIG. 2, and a test target other than the feedforward amplifier can be used. As a method of giving fluctuation to the frequency division ratio, a method other than the method using the PN code can be used.

[0027]

As described above, according to the test apparatus of the present invention, different phase fluctuations are given to the oscillation outputs of the respective oscillation circuits, so that overlapping of peaks and the like can be prevented, and It is possible to more accurately evaluate and test the capability of a barrel amplifier. Further, a simple device configuration is sufficient.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a test apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a configuration of an amplifying device to be tested in this embodiment.

FIG. 3 is a diagram showing an output spectrum of the amplifying device in the embodiment.

FIG. 4 is a diagram illustrating the effect of the present embodiment by showing the output spectrum of the conventional amplifying device shown in FIG.

FIG. 5 is a block diagram illustrating a configuration of a test apparatus according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a test apparatus according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing a schematic system configuration of a mobile communication base station apparatus.

FIG. 8 is a block diagram showing a configuration of a test apparatus according to a conventional example.

FIG. 9 is a diagram showing the overlap of the peak of the oscillation circuit output in this conventional example.

FIG. 10 is a diagram showing cancellation of an output of an oscillation circuit due to a reverse phase in the conventional example.

[Explanation of symbols]

14 amplifier 20 reference oscillator 22-1,22-2, ... 22-n oscillation circuit 24 combining circuit 26, 44 the test apparatus 28-1,28-2 ... 28-n PN modulation circuit 46 control circuit f _1, f ₂ ... f _n carrier frequency

Continued on the front page (72) Inventor Masaaki Fujiwara 5-1-1, Shimorenjaku, Mitaka City, Tokyo Japan Radio Co., Ltd. (72) Inventor Akira Yamada 5-1-1, Shimorenjaku, Mitaka City, Tokyo Japan Radio Stock In-company (72) Inventor Toshio Nojima 2-10-1 Toranomon, Minato-ku, Tokyo NTT Mobile Communication Network Co., Ltd. (56) References JP-A-58-75342 (JP, A) JP-A-58-75342 60-93360 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/00 G01R 31/28 G01R 23/20 H04B 17/00

Claims (6)

(57) [Claims] A reference oscillation circuit that oscillates at a predetermined frequency;
A plurality of oscillation circuits that oscillate at different frequencies while using the oscillation output of the reference oscillation circuit as a reference of the oscillation phase; a synthesis circuit that synthesizes the oscillation outputs of the plurality of oscillation circuits and supplies the oscillation output to an amplification device to be tested; A test apparatus for testing or evaluating an amplifying apparatus by simultaneously supplying a plurality of frequency components, comprising: phase fluctuation means for giving different fluctuations to the oscillation output phases of the plurality of oscillation circuits, respectively. Testing equipment. 2. The test apparatus according to claim 1, wherein the phase fluctuation means includes a modulation circuit that applies random phase or frequency modulation to the oscillation outputs of the plurality of oscillation circuits. 3. The test apparatus according to claim 1, wherein the plurality of oscillation circuits oscillate at different frequencies by dividing the oscillation output of the reference oscillation circuit by different division ratios, and the phase fluctuation means includes: And a control unit for giving a fluctuation to the frequency division ratio of the plurality of oscillation circuits. 4. The test apparatus according to claim 3, wherein said control means sets a frequency division ratio using a pseudo-noise code. 5. The test apparatus according to claim 1, wherein the phase fluctuation means includes a plurality of modulation circuits for applying random phase or frequency modulation to the oscillation output of the reference oscillation circuit. 6. The test apparatus according to claim 2, wherein the modulation circuit is a modulation circuit using a pseudo noise code as a signal source.