JP4976583B2 - Strain measuring device - Google Patents

Description

  The present invention is a test for measuring distortion of an RF communication device (hereinafter referred to as “front device”) made of semiconductor or metal, which is used for signal transmission, for example, for a front end of a mobile communication terminal. Regarding technology. In particular, as a front device, for example, in a mobile communication terminal, a coupling device that sends a transmission signal from a transmission unit to an antenna and a reception signal from the antenna to a reception unit (hereinafter referred to as a duplexer). In addition, there are switch devices and amplifiers that are coupled to the duplexer. The present invention relates to a technique for measuring distortion generated from them and falling within a band at the time of reception.

  In recent years, as mobile communication terminals (so-called portable terminals) have become smaller and more sophisticated, front devices used for front ends have become smaller and more complex. On the other hand, it has also been proposed that noise components and distortion components that are considered to be possessed by the front device may affect reception sensitivity.

  By the way, the duplexer and the switch device are generally received as passive elements, and in these, the distortion component is dominant over the noise component, and the measurement requirement of the distortion component is increasing. Even if the influence of the duplexer and switch device on the reception sensitivity is dominated by the harmonic distortion component, since it is a passive element, the distortion component is generated at a considerably low level. A wide measurement dynamic range is required. Note that the distortion component in question here is an unnecessary wave component caused by the nonlinearity of the element. In other words, a signal input to the element is generated by a harmonic component generated by nonlinearity in the element, a component generated by intermodulation including the input signal and the generated harmonic, and mutual modulation by a plurality of input signals. Components that fall within the reception band are considered as distortion components.

  As a measurement of distortion (modulation distortion) of a communication device or the like, there is a technique in which the measurement level range (dynamic range) of distortion reduces the influence of noise and unnecessary waves as described in Patent Document 1. However, it is difficult to measure a wide dynamic range distortion at a very low level like a passive element.

  In general, the following devices (1) and (2) are considered and used as a device for measuring the influence of distortion on the reception sensitivity of a mobile communication terminal of a passive element. As described above, the duplexer includes an antenna end to which an antenna is connected (hereinafter referred to as “ANT end”) and a receiving end to which a receiving unit is connected (hereinafter referred to as “Rx end”). , Having a transmission end (hereinafter referred to as “Tx end”) to which the transmission unit is connected, and passing a transmission signal from the Tx end to the ANT end as shown in FIG. 6 (hereinafter referred to as “Tx band”). ) And a band pass filter of a frequency band (hereinafter referred to as “Rx band”) that allows a received signal to pass from the ANT end to the Rx end. These band-pass filters also serve as a separation function that cuts off the flow of signals from the transmission unit to the reception unit and from the reception unit to the transmission unit. Here, the Tx band and the Rx band are collectively referred to as a communication band.

(1) IMD measurement (Inter Modulation Distortion: measurement of modulation distortion)
As shown in FIGS. 7 and 8, this is a signal Tx having the same frequency as the transmission signal to be transmitted by the mobile communication terminal (hereinafter, Tx may indicate the transmission signal or its frequency). ) To the Tx end. Then, a signal expected to be generated as a distortion component of the frequency Rx in the Rx band as a distortion component when mixed with the signal Tx in advance to the ANT end (each signal having a frequency of Rx-Tx, 2Tx-Rx, Tx + Rx, 2Tx + Rx). In this example, the distortion component is measured at the Rx end.

  Specifically, in FIG. 7, the first signal source 11 outputs the signal Tx, amplifies it by the power amplifying means 20a, and the unnecessary wave elimination filter 70a configured by a high-pass filter or a notch filter, Harmonics and noise components are removed and further sent to the Tx end of the duplexer 31 that is the DUT 30 via the circulator 80a. On the other hand, the second signal source 60 generates signals by switching the signals of the frequencies Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx, and again by the unnecessary wave removal filter 70c configured by a high-pass filter and a notch filter. These harmonics and noise components are removed and sent to the ANT end of the duplexer 31 via the circulator 80b. Then, the Rx component output from the Rx end is band-limited by the measuring means 90 as a distortion component and measured. The level required for measurement is −100 dBm or less as shown in FIG.

(2) IM3 measurement (3rd Inter Modulation; measurement of two-signal third-order modulation distortion)
As shown in FIG. 9 and FIG. 10, the signal Rx having the same frequency as the received signal to be received by the mobile communication terminal is input from the reference signal source 60a to the ANT end, and the third signal source 14 and the fourth signal source When the signal source 15 is mixed with the signal Rx in advance, a signal (frequency signals Tx−Δf / 2, Tx + Δf / 2x) that is expected to be generated in the Rx band as a distortion component is input to the Tx end. This is an example in which a frequency component that enters the Rx band at the end is measured as a distortion component.

  Specifically, in FIG. 9, the third signal source 14 and the fourth signal source 15 have a frequency of Tx−0.5 MHz (Δf = 1 MHz), Tx + 0.5 MHz as signals in the vicinity of the signal Tx. , Are amplified by the power amplifying means 20a and 20b, respectively, and the harmonics and noise components of the signals Tx−0.5 MHz and Tx + 0.5 MHz are removed by unnecessary wave elimination filters 70a and 70b. Further, in addition to the superimposing means 100, two signals are sent to one signal path to the Tx end of the duplexer 31 through the circulator 80a. On the other hand, a reference signal source 60a generates a signal Rx having the same frequency as the received signal, an unnecessary wave removing filter 70d removes the higher harmonics and noise components, and sends the signal to the ANT terminal via the circulator 80b. . Then, the Rx-1 MHz component and the Rx + 1 MHz component output from the Rx end are subjected to band limitation by the measuring unit 90 as a distortion component and measured. The level required for measurement is −111 dBm or less as shown in FIG.

  JP 2005-121494 A

  According to the above (1) IMD measurement method, when the second signal source 60 generates and tests a signal having a frequency of 2Tx-Rx, it is possible to measure distortion close to the purpose. However, when the signals having the frequencies Rx−Tx, Tx + Rx, and 2Tx + Rx are generated and tested, the dynamic range necessary for the target distortion measurement cannot be secured, and the target distortion measurement is not necessarily performed. I could not say it. As an example of the frequency, Tx = 1785 MHz, Rx = 1850 MHz, Rx−Tx = 65 MHz, 2Tx−Rx = 1720 MHz, Tx + Rx = 3635 MHz, and 2Tx + Rx = 5420 MHz. Considering the whole measurement system, it is very wide band.

  Considering the reason why the distortion measurement is difficult, when the second signal source 60 generates the signal 2Tx-Rx (signal of frequency 2Tx-Rx), the unnecessary wave elimination filter 70c also has the signal 2Tx-Rx. The filter configuration is passed. Since the frequency of the signal 2Tx-Rx is substantially within the communication band as shown in FIG. 8 (see FIG. 6), the ANT end, circulator 80b, unnecessary wave elimination filter 70c, second signal source in FIG. The 60 system has improved impedance matching. In other words, the signal Tx, the signal 2Tx-Rx, and the distortion component Rx are measured with good matching.

  On the other hand, when the second signal source 60 outputs the signal Rx−Tx, the signal Tx + Rx, and the signal 2Tx + Rx, the pass band of the unnecessary wave elimination filter 70c is changed according to the signal. In this case, as can be understood from FIG. 8, the unnecessary wave removal filter 70c is outside the band of the unnecessary wave removal filter 70c for the signal Tx and the distortion component Rx. In this case, in this case, the signal Tx and the distortion component For Rx, impedance matching is not achieved. For example, when a signal and a signal reflected due to impedance mismatch are combined, the combined signal may be distorted due to a difference in phase. In particular, as shown in FIG. 8, when distortion of 80 dB or less is a problem for a signal, the influence of impedance mismatch is inevitable.

  Accordingly, one of the objects of the present invention is to enable a wide dynamic range distortion measurement by maintaining a good impedance matching state when the second signal source 60 side is viewed from the ANT end. It is.

  In addition, the above (2) IM3 measurement method requires that the superimposing circuit 100, the unnecessary wave removing filters 70a, 70b, 70d and the circulators 80a, 80b are complicated from the two signal sources, and the scale is increased. There are drawbacks. Similarly, (1) the IMD measurement method also uses unnecessary wave elimination filter 70a and circulators 80a and 80b. In particular, since the signal-to-noise ratio is deteriorated due to the loss of the superimposing circuit or the noise of the power amplification means, an unnecessary wave removal filter using a notch filter is used. In addition, there is a problem such as an increase in loss due to the addition of the unnecessary wave removal filter, and appropriate design is not easy.

  In these distortion measurements, distortion components at a level of -100 dBm or less are measured, so that noise becomes a problem in securing the dynamic range, and therefore measurement errors due to the introduction of unnecessary wave signals are a concern. Therefore, it is considered that the configuration shown in FIGS. 9 and 7 is adopted. In particular, since the signal-to-noise ratio is deteriorated due to the loss of the superimposing circuit or the noise of the power amplification means, an unnecessary wave removal filter using a notch filter is used. In addition, there is a problem such as an increase in loss due to the addition of the unnecessary wave removal filter, and appropriate design is not easy.

  However, if the frequency relationship input to the duplexer, which is the device under test, is known, the distortion component in the Rx band (reception band) is specified by the relationship of the harmonics (that is, the frequency of the distortion component is known). ) Focused on the fact that measurement can be performed with a configuration in which measurement conditions are arranged.

  Therefore, another object of the present invention is to enable measurement with a simple configuration by measuring in a narrow band with good matching without being affected by unnecessary waves on the signal source side.

Specifically, in order to achieve the above object, the invention according to claim 1 transmits a transmission signal in a predetermined transmission band within a predetermined communication band, and a predetermined reception band having a frequency different from the predetermined transmission band. Used in a mobile communication device that receives an incoming signal within, and has an antenna end, a transmitting end, and a receiving end, and the transmitting end and the antenna end in the predetermined transmission band, and within the predetermined receiving band A distortion measuring device for measuring distortion output to the receiving end of the front device (30) including at least a coupling device (31) for coupling the antenna end and the receiving end respectively. A signal having the same frequency as that of the transmission signal and a signal having a frequency ± Δf / 2 are generated, and based on them, a frequency near the frequency of the transmission signal is generated at the transmission end, and a frequency difference Δf between them is the predetermined transmission band. Frequency components of the two RF signals within range generates including first signal, second signal source for outputting the two RF signals from the one output terminal and (11a), receiving from the receiving end signal A spectrum analyzer (13) for measuring the signal, a signal analyzer having a single housing, a power amplifying means (20a) for receiving and amplifying the first signal and directly outputting it to the transmitting end; A reference signal source (60a) for generating and outputting a second signal corresponding to the incoming signal, and a one-way coupling means for receiving the second signal and sending it to the antenna end and blocking the signal from the antenna end (80), and the spectrum analyzer is configured to select a frequency component generated by the first signal and the second signal in the front device and measure it as a distortion component.
According to a second aspect of the present invention, in the first aspect of the invention, when the frequency of the transmission signal is Tx, the frequencies of the two RF signals are Tx−Δf / 2 and Tx + Δf / 2, and distortion is caused. The component is a frequency component of Rx−Δf and Rx + Δf when the frequency of the second signal is Rx.
According to a third aspect of the invention, in the invention of the first or second aspect, the frequency resolution bandwidth of the spectrum analyzer is 300 Hz to 10 Hz.

  According to the first and second aspects of the invention, for example, two signals including a signal Tx−Δf / 2 and a signal Tx + Δf / 2, which are simultaneously generated by frequency conversion between a signal of frequency Tx and a signal of frequency Δf / 2. By using, even if a component of the frequency Tx leaks due to the frequency conversion, it can be measured with a simple configuration without being affected by the leak.

  In addition, since all of the inventions according to the third aspect are impedance-matched and limited to a narrow band of 300 Hz or less, measurement can be performed while reducing the influence of noise, unnecessary waves, and the like.

It is a figure which shows the function and structure of the 1st Embodiment of this invention. It is a figure which shows the function and structure of the branch matching means of FIG. It is a figure which shows the characteristic of each filter in a branch matching means. It is a figure which shows the example of application of 1st Embodiment to a different floto device. It is a figure which shows the implementation result by 1st Embodiment. It is a figure which shows the function and structure of 2nd Embodiment. It is a figure for demonstrating the function of a duplexer. It is a figure which shows one conventional measurement structural example (example of IMD measuring method). It is a figure which shows the frequency relationship of the signal in the structural example of FIG. It is a figure which shows another conventional measurement structural example (example of IM3 measuring method). It is a figure which shows the frequency relationship of the signal in the structural example of FIG.

  The embodiment according to the present invention will be described by dividing it into a first embodiment according to FIG. 1 and a second embodiment according to FIG. The first embodiment is an improved embodiment of the conventional IMD measurement method described in the above “Background Art”. The second embodiment is an embodiment that is also an improvement over the conventional IM3 measurement method. Therefore, FIGS. 6 and 8 are applied to the first embodiment according to FIGS. 1 to 3 as they are. Similarly, FIGS. 6 and 10 are applied to the second embodiment according to FIG. 1 to 10 indicate the same function.

[First Embodiment]
The first embodiment will be described with reference to FIGS. FIG. 1 shows a configuration in which the distortion of the duplexer 31 is measured as the DUT 30 as in FIG.

  In FIG. 1, the signal Tx from the first signal source 11 is amplified by the power amplification means 20 a and input to the Tx end of the duplexer 31. On the other hand, the second signal source 60 switches and outputs signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx, and inputs them to the ANT end of the duplexer 31 via the branch matching unit 50 and the branching unit 40. The band is limited by the spectrum analyzer 13 connected to the Rx end of the duplexer 31, and the distortion component Rx appearing at the Rx end is measured. As shown in FIG. 8, the distortion component Rx is an Rx component having the same frequency as the frequency to be received when the duplexer 31 is used in a mobile communication terminal.

Here, the configuration of FIG. 1 is different from the configuration of FIG. 7 in the following parts (1A) to (1D).
(1A) In the signal system on the ANT end side in FIG. 1, the frequency components generated on the duplexer 31 side for each signal from the second signal source 60 and on the ANT end except for the unnecessary wave elimination filter 70c in FIG. That is, the branch matching means 50 that can achieve impedance matching for both the Tx component and the Rx component is used.
(1B) In the signal system on the Tx end side in FIG. 1, the signal is input from the power amplification means 20a to the Tx end except for the unnecessary wave elimination filter 70c in FIG.
(1C) In the signal system on the Rx end side in FIG. 1, the distortion is measured with a spectrum analyzer that can measure the level by limiting to a narrow band.
(1D) The branching unit 40 composed of the directional coupling unit receives a signal from the second signal source 60 input via the branch matching unit 50, terminates one end with a terminator 41, and the other end To the power meter 42 side for output. This is for monitoring the level (power) of the signal input to the ANT end of the duplexer 31 by the power meter 42, and is connected by matching the impedance related to the input / output of the branching means 40. Since there is no particular influence on the distortion component, detailed description is omitted.

Hereinafter, (1A) (1B) (1C) will be described in detail.
About (1A) (About the branch matching means 50 in the ANT end side signal system)
This will be described with reference to FIGS. 1, 2A, 2B, and 8. FIG. The second signal source 60 in FIG. 1 switches the signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx to the ANT end of the duplexer 31 via the branch matching unit 50 and the branching unit 40 as the second signal. input. At that time, the second signal has a very wide band. To reprint the above example, Tx = 1785 MHz, Rx = 1850 MHz, Rx−Tx = 65 MHz, 2Tx−Rx = 1720 MHz, Tx + Rx = 3635 MHz, and 2Tx + Rx = 5420 MHz. Therefore, when the second signal is input to the ANT terminal, a filter for passing the second signal and removing other frequency components and noise at the same time is required (the “pass filter 51” described later is used). Applies to that filter.) In this case, impedance matching is achieved in the pass band of the filter, but impedance matching cannot be achieved in the communication bands (Tx band and Rx band) outside the pass band.

  On the other hand, a signal Tx is input to the Tx end of the duplexer 31 as the first signal. Then, a distortion component Rx (frequency Rx is a reception frequency when used as mobile radio, but in this case, the frequency when the distortion component is generated) is generated in the duplexer 31. To do. The signal Tx input into the duplexer 31 and the generated distortion component Rx are affected by impedance viewed from the ANT end toward the second signal limit 60 side. Therefore, the branch matching means 50 is designed to match impedance when the ANT end is viewed from the second signal source 60 side, and impedance matching when the second signal source 60 side is viewed from the ANT end.

  FIG. 2A shows a detailed functional configuration of the branch matching unit 50. In FIG. 2A, three resistors R form a Δ-shaped branch (which may be T-shaped (Y-shaped)). The first end, which is one end of the Δ branch, is connected with a characteristic impedance Zo by matching over a wide band including the frequency band of the second signal and the communication band. Between the second end of the Δ-branch and the second signal source 60, the signals Rx−Tx, 2Tx−Rx, Tx + Rx, 2Tx + Rx sent from the second signal source 60 are switched according to the signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx. A pass filter 51 that passes the signal is connected. In FIG. 2B, the characteristics of the pass filter are indicated by a solid line of a double line (in addition, there is no problem even if the characteristic is indicated by a double dotted line). In FIG. 2B, when the second signal is a signal Rx-Tx, 2Tx-Rx, the pass filter 51 is a low-pass characteristic impedance Zo that allows the signals to pass therethrough and blocks signals having a frequency equal to or higher than the Tx band. When the second signal is a signal Tx + Rx or 2Tx + Rx, the high-pass type (band) having a characteristic impedance Zo that passes the signals and blocks signals having frequencies below the Rx band. (It may be a path type). Therefore, the signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx always enter the pass band of the pass filter 51 at the time when they are output, and the signal Tx and distortion in the communication band (Tx band + Rx band) Since the component Rx always enters the stop band of the pass filter 51, it does not pass through the second end side.

  2A has characteristics that the signal Tx and the distortion component Rx in the communication band (Tx band + Rx band) enter the blocking region of the pass filter 51, so that the signal from the second signal source 60 If there is an unnecessary component or noise included in the communication band in the second signal, it also has an effect of removing them.

On the other hand, a communication band termination filter 52 is connected to the third end of the Δ branch. 2B, when the second signal is a signal Rx-Tx, 2Tx-Rx, the communication band termination filter 52 passes a signal having a frequency equal to or higher than the Tx band and passes the signal Rx-Tx. 2Tx-Rx, a high-pass filter characteristic terminated with a characteristic impedance Zo. When the second signal is a signal Tx + Rx, 2Tx + Rx, a low-pass filter characteristic terminated with a characteristic impedance Zo that passes signals having frequencies below the Rx band and blocks the signals Tx + Rx, 2Tx + Rx is obtained. Therefore, when viewed from the first end, the signal (signal Tx, distortion component Rx) within the communication band is always terminated at the characteristic impedance Zo at the third end. Since the third end blocks the signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx, these signals do not pass through the third end side and pass through the second end side described above to the first end. Sent to the end.
The communication band termination filter 52 can also be configured as a band-pass filter that allows only signals within the communication band to pass (the configuration is simpler).

  By configuring the branch matching means 50 as described above, the signal system from the first end side to the third end side indicated by the rough dotted line in FIG. 2A has characteristics for signals (signal Tx, distortion component Rx) within the communication band. A signal system from the second end side to the first end side, which is configured by the impedance Zo and indicated by a fine dotted line in FIG. 2A, is configured by the characteristic impedance Zo for the signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx. Therefore, the impedance matching can be achieved for any related signal.

(1B) (1C) (Tx end side and Rx end side signal systems)
Each of the signal systems on the Tx end side and the Rx end side in FIG. 1 is configured with a characteristic impedance Zo. Here, in the signal system on the Tx end side, the major problem in distortion measurement is that the sideband noise (generally, SSB of the signal Tx itself from the first signal source 11 is understood from FIG. 8. If there is an Rx component (hereinafter also referred to as SSB noise Rx) as phase noise), it is superimposed on the distortion component Rx generated in the duplexer 31, so the dynamic range is limited. Is Rukoto. There is no problem as long as the SSB noise Rx is sufficiently smaller than the distortion component Rx to be measured. As described above, if the frequency is Tx = 1785 MHz and Rx = 1850 MHz, the noise component at the frequency of +65 MHz of the signal Tx corresponds to the SSB noise Rx.

For the magnitude of the noise component (including phase noise) of the signal source in the mobile communication terminal (portable terminal), a specification represented by the following equation is generally required.
Noise component [dBm / Hz] = guaranteed reception sensitivity level [dBm] -10 Log (occupied frequency bandwidth)
Noise level [dBm / Hz] for signal = −signal level [dBm] + noise component

  The meaning of the above formula is that if reception is performed with the occupied frequency bandwidth, the ZH noise component per 1 Hz is added by the occupied frequency (noise per 1 Hz × occupied frequency band). That is, a signal source is necessary. In other words, when a signal having the same level as the guaranteed reception sensitivity level is received with the occupied frequency bandwidth, the noise-to-signal ratio = S / N = 0 dB.

Here, the guaranteed reception sensitivity level (required specification) for distortion measurement is −110 dBm, the signal levels of the signals Rx−Tx, 2Tx−Rx, Tx + Rx, 2Tx + Rx are −20 dBm as shown in FIG. 8, and the communication method is W-CDMA. If the occupied frequency bandwidth is 3.84 MHz, the required noise level is as follows.
Noise level = −110 − (− 20) −10 Log (3.84 × 10 ⁶ )
≒ -155 [dBm / Hz]

  However, in measuring this distortion, it is only necessary to measure in the dynamic range necessary for distortion measurement, and it is not necessary to receive in the occupied frequency bandwidth. Thus, if the resolution bandwidth (referred to as RBW, which is the so-called measurement bandwidth) of the spectrum analyzer 13 that measures the distortion component Rx is limited to 3 kHz, 300 Hz, and 30 Hz, the occupied frequency bandwidth is measured. = S / N is improved by about 30 dB, about 40 dB, and about 50 dB compared to 3.84 MHz. Therefore, when the guaranteed reception sensitivity level (required specification) for distortion measurement is −110 dBm and the signal levels of the signals Rx−Tx, 2Tx−Rx, Tx + Rx, and 2Tx + Rx are −20 dBm as in the above example, the measurement by the spectrum analyzer 13 is performed. When the bandwidth, that is, the resolution bandwidth is limited to 3 kHz, 300 Hz, and 30 Hz, the noise levels required for the signal source are about −135 dBm / Hz, −125 dBm / Hz, and −115 dBm / Hz, respectively, and the noise component is greatly restricted. You do n’t have to. As the noise component restriction becomes thinner in this way, processing for removing unnecessary wave components such as noise with a notch filter or the like as in the prior art becomes unnecessary.

  In order to improve the measurement accuracy of the distortion component Rx, it is desirable to measure with a margin of S / N = 6 dB. Further, a resistor pad having a characteristic impedance Zo may be used to match impedance between circuits (for example, a 3 dB pad is used for the Rx end, the ANT end, and Rx), but this deteriorates the S / N. Therefore, it is necessary to consider the influence on the noise component. For example, as the first signal source 11, if the noise level is about −145 dBm / Hz or less at the frequency point of the distortion component Rx, the measurement bandwidth (resolution bandwidth) of the spectrum analyzer 13 is 300 Hz. Since the required noise level is −125 dBm / Hz, a margin of 20 dB is created. Therefore, this margin is reduced to S / N = 6 dB and a loss at the resistance pad.

  From the above, it is desirable that the measurement bandwidth (resolution bandwidth) of the spectrum analyzer 13 is 300 Hz to 10 Hz. The first signal source 11 desirably has a noise level of about −145 dBm / Hz or less at the frequency point of the distortion component Rx, but the measurement bandwidth (resolution bandwidth) of the spectrum analyzer 13 is appropriately set according to the noise level of the signal source. You can also respond by selecting

  FIG. 1 illustrates the case where only the duplexer 31 is used as the device under test DUT 30, but as shown in FIG. 3, the switch 32 made of a semiconductor is connected to the ANT end of the duplexer 31 together with the terminator 33 as the device under test DUT 30. Even in the connected configuration, the distortion component generated by the duplexer 31 and the switch 32 can be measured in the same manner as in FIG. The switch 32 has a parent terminal on the branching means 40 side, the ANT end and the terminator 33 are connected to the child terminal, and the signal input to the parent terminal is switched to the terminator 33 or the ANT terminal for connection. It is the composition which is done.

  Alternatively, the duplexer 31 having a known characteristic may be used as one of the components of the strain measuring apparatus, and only the switch 32 may be measured as the device under test DUT 30. In this case, the distortion of the switch 32 can be measured by considering the known characteristics of the duplexer 31 with respect to the measured value of the spectrum analyzer 13.

[Example according to the first embodiment]
FIG. 4 shows the result of the implementation according to the configuration of FIG. The measurement condition is that the frequency of the first signal source 11 is 1750 MHz, and the frequency of the second signal source 60 is Rx-Tx, 2Tx-Rx, Tx + Rx, and 2Tx + Rx, respectively 100 MHz, 1650 MHz, 3600 MHz, and 5350 MHz. Each level (level at the ANT end measured by the power meter 42) is measured under the condition of −20 dBm. Further, the spectrum analyzer 13 is tuned to the distortion component Rx = 1850 MHz and measures the measurement bandwidth, that is, the resolution bandwidth (RBW) at 30 Hz. For comparison, the measured values for both the case of the configuration of the conventional example and the case of the configuration of FIG. 1 are shown.

  In FIG. 4, according to the conventional example, the distortion component Rx when the second signal frequency is Rx−Tx is −103.39 dBm, and the distortion component when the second signal frequency is Tx + Rx is −92.77 dBm. However, these are breaking the standard -110 dBm. On the other hand, according to the embodiment of FIG. 1, the measured value is about −140 dBm or less at any frequency of the second signal, which satisfies the standard.

  As the signal analysis apparatus 10 including the first signal source 11 and the spectrum analyzer 13, an MS2692A signal analyzer manufactured by the applicant of the present invention, which is incorporated in one housing, is used. As the second signal source 60, an MG3691B synthesizer manufactured by the applicant of the present invention is used.

[Second Embodiment]
The second embodiment will be described with reference to FIGS. FIG. 5 shows a configuration for measuring distortion generated by the duplexer 31 and the switch 32 as the DUT 30a.

  FIG. 5 shows that a signal Rx having the same frequency as the received signal to be received by the mobile communication terminal is received by the reference signal source 60a at the switch 32 (or ANT end) at the ANT end, and at the Tx end by the two signal sources 11a , A signal (frequency signals Tx−Δf / 2 and Tx + Δf / 2) that are expected to be generated in the Rx band as a distortion component when mixed with the signal Rx in advance is input, and the signal enters the Rx band at the Rx terminal. In this example, frequency components Rx−Δf and Rx + Δf are measured as noise components.

  That is, the two signal sources 11a in FIG. 5 output, for example, signals having frequencies of Tx−0.5 MHz (Δf = 1 MHz) and Tx + 0.5 MHz as signals in the vicinity of the signal Tx, respectively, and power amplification means. Amplified by 20 a and sent to the Tx end of the duplexer 31. On the other hand, the reference signal source 60a generates a signal Rx having the same frequency as the received signal and sends it to the switch 32 (or ANT end) via the circulator 80 and the branching means 40. Then, the component Rx-1 MHz and the component Rx + 1 MHz output from the Rx end by the spectrum analyzer 13 are measured as distortion components.

The main difference between FIG. 5 and FIG. 9 is in the following points (2A), (2B), and (2C).
(2A) In FIG. 9, a signal is generated by superimposing a signal from the third signal source 14 and a signal from the fourth signal source 15, but in FIG. 5, two signals generated by frequency conversion are Used.
(2B) The unnecessary wave elimination filters 70a, 70b, and 70d used in FIG. 9 are not required in FIG. 5, and accordingly, the resolution band RBW (measurement band) in the spectrum analyzer is limited.
(2C) The branch means 40 is provided. However, this is the same as the reason (1D) above, and the description is omitted.

Hereinafter, the above (2A) and (2B) will be described in detail.
(2A) Configuration of Two-Signal Source 11a In FIG. 5, the two-signal source 11a internally generates a high-frequency band signal Tx and a low-frequency band signal ± Δf / 2, and converts the signal Tx into a signal ± Δf / 2. The frequency is converted by mixing with a mixer, and the signals Tx−Δf / 2 and Tx + Δf / 2 on both sides of the signal Tx are output from one output terminal to the power amplification means 20a. That is, the two-signal source 11a internally generates a carrier signal having a frequency Tx and a digital baseband signal composed of two tone signals having a frequency ± Δf / 2, and D / A-converts this baseband signal. Thus, two RF tone signals Tx−Δf / 2 and Tx + Δf / 2 are output by performing frequency conversion using the carrier wave signal. For example, FIG. 10 shows an example in which Δf = 1 MHz. Since it is frequency conversion, as a component that is actually output, in addition to the signal Tx−0.5 MHz and the signal Tx + 0.5 MHz, a residual component Tx due to frequency conversion is also output. However, this is a component that does not affect the measurement of the distortion components of the component Rx-1 MHz and the component Rx + 1 MHz measured with the spectrum analyzer 13 being band-limited.

(2B) Unnecessary wave removal filter (including notch filter for noise removal) is unnecessary. Particularly, the problem in distortion measurement is that the signal Tx−Δf / 2, the signal Tx + Δf / This is because if the Rx-Δf and Rx + Δf components are included as noise in the sidebands of 2 and the signal Rx itself, they become distortion measurement errors as they are. In particular, if Δf = 1 MHz, noise components at frequencies Rx−1 MHz and Rx + 1 MHz are a serious problem. Conventionally, this noise has been reduced by a notch filter.

  With the configuration of the two-signal source 11a described in (2A) above, the loss is reduced by eliminating the superimposing circuit, and the S / N deterioration is avoided accordingly. Then, as described in the above (1B) and (1C), the spectrum analyzer 13 performs band-limited measurement at 300 Hz to 10 Hz, thereby eliminating unnecessary wave removal filters (including notch filters for noise removal). Nearly satisfactory results were obtained.

For example, there is a measurement request with the specification that the level of the signal Rx is −30 dBm and the dynamic range of distortion measurement is −82 dB. Then, it is necessary to measure a level of -112 dBm. Therefore, as a signal from each of the two signal sources 11a and the reference signal source 60a, a noise component of −152 dBm / Hz at Rx−1 MHz and Rx + 1 MHz is used to set the measurement band of the spectrum analyzer 13 to 300 Hz for distortion measurement. If the required S / N is 6 dB,
−152 + 10 Log 300 + 6 = −121 [dBm]
Can be measured, so the dynamic range can be covered sufficiently. As the signal analysis apparatus 10a including the two signal sources 11a and the spectrum analyzer 13, an MS2692A signal analyzer manufactured by the applicant of the present invention, which is incorporated in one housing, is used. Since it is sufficient in performance and is an integrated type, the configuration becomes simple. As the reference signal source 60a, an MG3691B synthesizer manufactured by the applicant of the present invention is used.

10 signal analyzer, 10a signal analyzer, 11 first signal source,
11a 2 signal source, 14 3rd signal source,
13 spectrum analyzer, 14 third signal source, 15 fourth signal source,
20a power amplification means, 20b power amplification means,
30 DUT (device under test), 30a DUT, 31 duplexer (coupling means), 32 switch,
33 Terminator,
40 branching means, 41 terminator, 42 power meter,
50 branch matching means, 51 path filter, 52 communication band termination filter,
60 second signal source, 60a reference signal source,
70a unwanted wave removal filter, 70b unwanted wave removal filter,
70c unnecessary wave elimination filter, 70d unnecessary wave elimination filter,
80 circulator, 80a circulator, 80b circulator, 80c circulator,
90 measuring means,
100 superimposing means,
R resistor,
Zo characteristic impedance

Claims (3)

Used for mobile communication equipment that transmits a transmission signal within a predetermined transmission band within a predetermined communication band and receives an incoming signal within a predetermined reception band having a frequency different from that of the predetermined transmission band. A coupling device (31) having a receiving end, and coupling the transmitting end and the antenna end within the predetermined transmission band, and the antenna end and the receiving end within the predetermined receiving band, respectively. A distortion measuring device for measuring distortion output to the receiving end of at least the front device (30) including:
Internally, a signal having the same frequency as the transmission signal and a signal having a frequency ± Δf / 2 are generated, and based on them, a frequency near the frequency of the transmission signal is generated at the transmission end, and the frequency difference Δf between the signals is the two RF signals within the width of a given transmission band generates including first signal, second signal source for outputting the two RF signals from the one output terminal and (11a), receiving from the receiving end signal A signal analyzer having a spectrum analyzer (13) for measuring the frequency component of
Power amplifying means (20a) for receiving and amplifying the first signal and directly outputting it to the transmitting end;
A reference signal source (60a) for generating and outputting a second signal corresponding to the incoming signal;
Unidirectional coupling means (80) for receiving and sending the second signal to the antenna end and blocking the signal from the antenna end;
With
The spectrum analyzer selects a frequency component generated by the first signal and the second signal in the front device and measures it as a distortion component.   When the frequency of the transmission signal is Tx, the frequencies of the two RF signals are Tx−Δf / 2 and Tx + Δf / 2, and the distortion component is Rx− when the frequency of the second signal is Rx. The distortion measuring apparatus according to claim 1, wherein the distortion measuring apparatus has frequency components of Δf and Rx + Δf.   3. The distortion measuring apparatus according to claim 1, wherein a frequency resolution bandwidth of the spectrum analyzer is 300 Hz to 10 Hz.

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