KR101184331B1 - Apparatus and method for detecting passive intermodulation distortion signal - Google Patents

Abstract

The present invention relates to a passive element intermodulation distortion signal measuring apparatus and method, the measuring apparatus comprising: a test signal generator for generating a test signal; A duplexer which transmits the test signal to a device under measurement and receives an intermodulation distortion signal of the device under measurement in accordance with the test signal; Converts the intermodulation distortion signal received by the duplexer into an intermediate frequency signal, generates a reference frequency signal to generate a tuning voltage corresponding to a phase difference with the intermediate frequency signal, and based on the tuning voltage, the intermodulation distortion signal A frequency correction circuit for outputting a correction frequency signal for correcting the phase difference of the signal and converting the intermodulation distortion signal into an intermediate frequency signal corrected for frequency drift based on the correction frequency signal; A band limiting filter for removing noise of the intermodulation distortion signal having the drift corrected through the frequency correction circuit; And a measuring device for measuring the strength of the intermodulated distortion signal from which the noise is removed. This eliminates the frequency drift of the received signal caused by the internal factors of the measuring device when measuring the passive element intermodulation distortion signal, so that the energy of the received signal is narrowed when the band of the received signal for signal measurement is limited. By positioning at, the measurement accuracy can be improved and the received signal can be measured stably and quickly.

Description

APPARATUS AND METHOD FOR DETECTING PASSIVE INTERMODULATION DISTORTION SIGNAL

The present invention relates to a passive element intermodulation distortion signal measuring apparatus and method, and more particularly, to eliminate frequency drift of a received signal caused by internal factors of the measuring apparatus when measuring passive element intermodulation distortion signal. Passive element intermodulation distortion signal measuring device to improve the measurement accuracy and to measure the received signal stably and quickly by placing the energy of the received signal in the narrow band when the band of the received signal for signal measurement is limited. And to a method.

When signal processing such as attenuation, amplification, band limitation, etc. is performed on an electrical signal using the signal processing apparatus, distortion may be added to the processed signal due to the nonlinear characteristics of the signal processing apparatus itself.

When inputting and processing various different frequency components into the active circuit of the signal processing apparatus, inter-modulation between the input signals occurs and unwanted harmonics are generated, which is called intermodulation distortion (IMD). Accordingly, mobile communication operators restrict the intermodulation distortion (IMD) characteristics of active devices such as RF power amplifiers, transmitters, and receivers as small as possible.

On the other hand, not only active elements, but also passive elements such as antennas, duplexers, combiners, and connectors among the signal processing devices of the communication system have nonlinear characteristics, and the intermodulation distortion characteristics of the passive elements are called PIMD (Passive InterModulation Distortion). do. PIMD can also affect overall system performance, so PIMD is also measured and regulated.

The basic method of measuring intermodulation distortion (IMD) is to apply two tones of the two frequencies close to the measurement frequency to the device under test (DUT), and output the output of the spectrum analyzer By observing by using the observation, the magnitude of the third harmonic harmonic of the two distorted frequencies is observed to determine the IMD value.

However, in the case of a high output active element, the distortion is relatively large, and thus the spectrum analyzer can be easily measured, whereas in the passive element, the amount of distortion is small, so it is not easy to measure the degree of intermodulation distortion. .

Accordingly, the PIMD measuring apparatus according to the prior art measures the PIMD signal by processing the IF signal using the DSP (Digital Signal Processing). According to the prior art, after converting a signal received from the device under measurement into an IF signal, the DSP board removes the noise of the measurement device from the received IF signal through digital filtering to find and measure the PIMD signal. The PIMD measurement method using digital filtering requires a high degree of digital filtering in order to ensure accuracy. However, when the digital filtering degree is increased, the measurement speed is increased due to an increase in data to be processed.

Another conventional PIMD measuring apparatus removes noise of a received signal using a band pass filter (BPF) and then measures the PIMD using a spectrum analyzer. Here, since the noise level of the received signal is proportional to the temperature and bandwidth of the PIMD measuring device, it is important to limit the bandwidth to the narrow band at the receiving end in order to accurately measure the received signal. However, if a frequency drift occurs in a received signal due to a reception path or a local signal generator present in the receiving device, the received signal cannot pass through the narrow band band limit filter, resulting in poor reception sensitivity or error in the measured value. There is a problem that occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and eliminates the frequency drift of a received signal caused by internal factors of the measuring device when measuring a passive element intermodulation distortion signal, thereby receiving a signal for measuring a signal. It is possible to improve the measurement accuracy by placing the energy of a received signal in a narrow band when the band limit is limited, and to provide an apparatus and method for measuring a passive element intermodulation distortion signal for stably and quickly measuring a received signal. There is.

The passive element intermodulation distortion signal measuring apparatus of the present invention for achieving the above object includes a test signal generator for generating a test signal; A duplexer which transmits the test signal to a device under measurement and receives an intermodulation distortion signal of the device under measurement in accordance with the test signal; Converts the intermodulation distortion signal received by the duplexer into an intermediate frequency signal, generates a reference frequency signal to generate a tuning voltage corresponding to a phase difference with the intermediate frequency signal, and based on the tuning voltage, the intermodulation distortion signal A frequency correction circuit for outputting a correction frequency signal for correcting the phase difference of the signal and converting the intermodulation distortion signal into an intermediate frequency signal corrected for frequency drift based on the correction frequency signal; A band limiting filter for removing noise of the intermodulation distortion signal having the drift corrected through the frequency correction circuit; And a measuring device for measuring the strength of the intermodulated distortion signal from which the noise is removed.

Here, the test signal generator includes a first signal generator for generating a first frequency signal; A second signal generator for generating a second frequency signal; A first amplifier for amplifying the first frequency signal; A second amplifier for amplifying the second frequency signal; And a power combiner configured to combine the amplified first and second frequency signals to generate a two-tone test signal.

The frequency correction circuit may include: a mixer for converting the intermodulation distortion signal received from the apparatus under measurement to an intermediate frequency signal and outputting the intermediate frequency signal to the band limiting filter; A reference frequency generator for generating a reference frequency signal; A phase-looked loop (PLL) unit configured to generate a tuning voltage corresponding to a phase difference between the reference frequency signal and the intermediate frequency signal; A voltage control oscillator outputting a correction frequency signal for correcting the phase difference of the intermodulation distortion signal based on the tuning voltage; The mixer may convert the intermodulation distortion signal into an intermediate frequency signal having a frequency drift corrected based on the correction frequency signal provided by the voltage controlled oscillator.

The PLL unit may include a first divider for dividing the reference frequency signal; A second divider for dividing the intermodulated distortion signal converted into the intermediate frequency signal into a signal having the same frequency as the first divider; And a differential amplifier generating a tuning voltage corresponding to a phase difference between the divided signal of the first divider and the divided signal of the second divider.

The method may further include a directional coupler (DC) interposed in an output line of the intermediate frequency signal output from the mixer to the band limiting filter and branching an output path of the intermediate frequency signal to the PLL unit.

The apparatus may further include an automatic gain adjuster (AGC) interposed in the output line of the intermediate frequency signal output from the directional coupler to the PLL unit.

A frequency correction circuit of the present invention for achieving the above object includes a reference frequency generator for generating a reference frequency signal; A mixer for generating an intermediate frequency signal based on the received signal and the corrected frequency signal; A first divider for dividing the reference frequency signal, and a second divider for dividing the received signal converted into the intermediate frequency signal into a signal having the same frequency as the first divider; A phase-looked loop (PLL) unit including a differential amplifier for generating a tuning voltage corresponding to a phase difference between the divided signal of the first divider and the divided signal of the second divider; A voltage control oscillator for outputting a correction frequency signal for correcting the phase difference based on the tuning voltage; The mixer is characterized in that for correcting the phase difference of the received signal based on the correction frequency signal provided by the voltage controlled oscillator.

The method may further include a directional coupler (DC) interposed in the intermediate frequency signal output line of the mixer to branch the output path of the intermediate frequency signal to the PLL unit.

The apparatus may further include an automatic gain adjuster (AGC) interposed in an output line of the intermediate frequency signal output from the directional coupler to the PLL unit.

A passive element intermodulation distortion signal measuring method of the present invention for achieving the above object comprises the steps of: generating a test signal and transmitting it to a device under measurement; Receiving an intermodulation distortion signal of the apparatus under test in accordance with the test signal; Converting the received intermodulation distortion signal into an intermediate frequency signal; Generating a reference frequency signal; Generating a tuning voltage corresponding to a phase difference between the reference frequency signal and the intermediate frequency signal; Outputting a correction frequency signal for correcting the phase difference of the intermodulation distortion signal based on the tuning voltage; Converting the intermodulated distortion signal to an intermediate frequency signal having a frequency drift corrected based on the corrected frequency signal; Removing noise of the intermodulation distortion signal with the drift corrected; And measuring the strength of the intermodulated distortion signal from which the noise is removed.

The correcting of the frequency drift of the intermodulated distortion signal may include converting the intermodulated distortion signal into an intermediate frequency signal having a frequency drift corrected.

The generating of the tuning voltage corresponding to the phase difference between the reference frequency signal and the intermediate frequency signal may include: dividing the reference frequency signal into a first divided signal; Dividing the intermodulated distortion signal converted into the intermediate frequency signal into a second divided signal having the same frequency as the first divided signal; And comparing the phase difference between the first divided signal and the second divided signal to generate a tuning voltage corresponding to the phase difference.

The method may further include amplifying the intermediate frequency signal to a size comparable with the reference frequency signal.

As described above, the passive element intermodulation distortion signal measuring apparatus and method of the present invention eliminate the frequency drift of a received signal caused by internal factors of the measuring apparatus when measuring the passive element intermodulation distortion signal, When the bandwidth of the received signal for measurement is limited, the energy of the received signal is located in a narrow band, thereby improving measurement accuracy and stably measuring the received signal stably.

1 is a control block diagram of a passive element intermodulation distortion signal measuring apparatus according to an embodiment of the present invention;
2 is a control block diagram of the frequency correction circuit of FIG.
3 is a control block diagram of the phase locked loop of FIG.
4 is a flowchart of a passive element intermodulation distortion signal measuring method according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a control block diagram of an apparatus for measuring passive intermodulation distortion (hereinafter, referred to as PIMD) according to an exemplary embodiment of the present invention.

As shown in FIG. 1, the PIMD measuring apparatus according to the present invention includes a first signal generator 1 for generating a first signal f1 and a second signal generator 3 for generating a second signal f2. And combine the first and second amplifiers 5 and 7, which amplify the first and second signals f1 and f2, respectively, and the amplified first and second signals f1 and f2. A power combiner 9 for generating a test signal and a test signal are input to a device under test (hereinafter referred to as a DUT) 20, and the reflected signal generated by the DUT 20 is inputted. A duplexer 11 for receiving, a frequency correction circuit 100 for correcting drift of a signal reflected through the duplexer 11, and a band pass filter for removing noise of the received signal for which drift is corrected. , BPF) and a meter 180 for measuring the spectrum of the received signal from which the noise is removed.

The first signal generator 1 generates a first signal f1 having a frequency f1, and the second signal generator 3 generates a second signal f2 having a frequency f2. The first signal f1 is amplified by the first amplifier 5 and the second signal f2 is amplified by the second amplifier 7. Here, the first signal f1 and the second signal f2 may apply signals of frequency bands that are close to each other.

The power combiner 9 combines the amplified first signal f1 and the second signal f2 to generate a two-ton test signal in which two frequencies f1 and f2 are combined.

The duplexer 11 inputs a test signal output from the power combiner 9 including the transmission port Tx and the reception port Rx to the DUT 20 through the transmission port Tx. The PIMD signal generated by the DUT 20 is input to the receiving port Rx of the duplexer 11 and output to the frequency correction circuit 100.

The frequency correction circuit 100 corrects the frequency drift of the PIMD signal received from the DUT 20, converts it into an intermediate frequency (IF) signal, and outputs it to the BPF 170. The frequency drift may occur as the PIMD signal is received and via the reception path, or may be generated by the signal generators 1 and 3 present in the PIMD measurement device. Accordingly, the frequency correction circuit 100 may increase the measurement accuracy of the PIMD signal by correcting the drift such that the highest output frequency band of the PIMD signal matches the filtering frequency of the BPF 170.

The BPF 170 removes the noise of the PIMD signal in which the drift is corrected, and outputs the noise to the measuring unit 180. The BPF 170 has the frequency of the PIMD signal output from the frequency correction circuit 100 as a center frequency fo as a reference for filtering, and the smaller the band width of the filtering is, the more effectively the noise is removed. can do.

The measuring unit 180 receives a band limited PIMD signal and measures a signal size.

With this configuration, the first signal f1 and the second signal f2 generated by the first signal generator 1 and the second signal generator 3 are amplified by the amplifiers 5 and 7, and then power is applied. In the combiner 9 two frequencies f1 and f2 are converted into a synthesized two-ton test signal. The test signal is input to the DUT 20 through the transmission port Tx of the duplexer 11, and the PIMD signal generated from the DUT 20 according to the test signal input is input to the receiving port Rx of the duplexer 11. It is transmitted to the frequency correction circuit 100. The frequency correction circuit 100 corrects the drift of the PIMD signal, and the corrected PIMD signal is measured by the measuring unit 180 after the noise is removed through the BPF 170.

As such, the PIMD measuring apparatus according to the present invention removes the frequency drift present in the PIMD signal received from the DUT 20 to correct the energy of the PIMD signal to be at the center of the BPF 170, and narrows the corrected PIMD signal. After band-limiting to the band BPF 170 to remove noise, the intensity of the PIMD signal is measured, thereby increasing the measurement accuracy of the PIMD signal and reducing the measurement time. Here, the configuration of the frequency correction circuit 100 to remove the frequency drift of the PIMD signal is as shown in FIG.

2 is a control block diagram of a frequency correction circuit 100 of a PIMD measuring apparatus according to the present invention, wherein the DUT 20 processes a 447 MHz radio signal allocated to a frequency band of a remote control signal according to the Korean Radio Law. In the case of a signal processing device, the frequency correction circuit 100 may be applied.

As shown in FIG. 2, the frequency correction circuit 100 passes through a mixer 110 and a mixer 110 that multiply a signal received from the DUT 20 by a correction frequency signal to generate an intermediate frequency (IF) signal. AGC to adjust the gain of the signal coupled by the directional coupler (DC) 120 and the directional coupler (DC) 120 for coupling the intermediate frequency (IF) signal transmitted to the BPF 170 (Automatic Gain Control) 130, a TCXO (Temperature Compensated Crystal Oscillator) 160 that outputs a reference frequency (Ref) signal, and a tuning voltage corresponding to a phase difference between a signal coupled with the reference frequency (Ref) signal ( Phase Control Oscillator (VCO) for transmitting a correction frequency signal to the mixer 110 based on a PLL (Phase Looked Loop) unit 150 for generating Vt) and a tuning voltage Vt provided by the PLL unit 150. 140.

The mixer 110 converts the PIMD signal into an intermediate frequency (IF) signal by multiplying the PIMD signal received from the DUT 20 by the correction frequency signal provided by the VCO 140.

The directional coupler (DC) 120 provides two transmission paths for transmitting an intermediate frequency (IF) signal (10 MHz) of the PIMD signal, so that the intermediate frequency (IF) signal of the PIMD signal is transferred to the BPF 170 and the PLL unit ( 150 respectively.

The AGC 130 may be interposed in the transmission path of the intermediate frequency (IF) signal branched from the directional coupler (DC) 120 and transmitted to the PLL unit 150. The AGC 130 adjusts the gain so that the intermediate frequency (IF) signal branched from the directional coupler (DC) 120 can be processed by the PLL unit 150.

The TCXO 160 is a temperature compensated crystal oscillator that generates a constant frequency and generates a reference frequency (Ref) signal for frequency correction. In the present embodiment, a case of generating a 16 MHz reference frequency (Ref) signal is illustrated, but this may be variously modified according to a system design method.

The PLL unit 150 generates a tuning voltage Vt corresponding to the phase difference between the intermediate frequency IF signal 10MHz and the reference frequency Ref signal output from the TCXO 160. That is, a tuning voltage Vt corresponding to the magnitude of the frequency drift of the received PIMD signal is generated.

The VCO 140 generates a correction frequency signal according to the tuning voltage Vt input from the PLL unit 150 and provides the correction frequency signal to the mixer 110. In the initial driving, the VCO 140 generates an initial signal for converting a PIMD signal, which is expected to be received in an abnormal state without drift, into an intermediate frequency (IF) signal. Thereafter, the VCO 140 generates a correction frequency signal by correcting the initial signal according to the tuning voltage provided by the PLL unit 150, and outputs the correction frequency signal to the mixer 110.

Accordingly, the mixer 110 may convert the PIMD signal into an intermediate frequency (IF) signal by multiplying the PIMD signal by the correction frequency signal.

When the frequency correction circuit 100 having such a configuration is used for PIMD measurement of a remote control signal processing apparatus that processes a wireless signal of 447 MHz, the remote control signal processing apparatus from the DUT 20 to the frequency correction circuit 100. The received 447MHz PIMD signal may have a frequency deviation Δ1 due to frequency drift.

The PIMD signal 447 MHz + Δ1 having a frequency drift is applied to the mixer 110 generating an intermediate frequency (IF) signal. The mixer 110 generates an intermediate frequency (IF) signal by multiplying the correction frequency (437 MHz) output by the VCO 140 and the PIMD signal (447 MHz + Δ1). Here, the VCO 140 outputs an initial signal (437MHz), so that the intermediate frequency (IF) signal generated through the mixer 110 includes a frequency deviation Δ1 (10MHz + Δ1). The intermediate frequency (IF) signal generated by the mixer 110 is branched by the directional coupler (DC) 120, and the gain is adjusted through the AGC 130, and then transferred to the PLL unit 150. The PLL unit 150 compares the reference frequency Ref signal generated by the TCXO 160 with the intermediate frequency IF signal 10MHz + Δ1 to generate a tuning voltage Vt corresponding to the phase difference between the two signals. The VCO 140 generates a correction frequency signal 437 MHz + Δ1 according to the tuning voltage Vt provided by the PLL unit 150, and transmits the generated correction frequency signal 437 MHz ?? Δ1 to the mixer 110. Output Accordingly, the mixer 110 may generate a 10 MHz intermediate frequency (IF) signal by correcting the frequency deviation Δ1 included in the PIMD signal 447 MHz + Δ1.

According to this configuration, the frequency correction circuit 100 may correct the drift of the PIMD signal received from the DUT 20 and transmit it to the measuring unit 180 through the BPF 170.

Meanwhile, the center frequency fo of the BPF 170 may be set to 10 MHz according to the frequency band of the intermediate frequency IF signal output from the frequency correction circuit 100, and the bandwidth BW may sufficiently remove noise. The size may be set to about 300 Hz.

3 is a control block diagram of the PLL unit 150 of FIG. 2.

As shown in FIG. 3, the PLL unit 150 divides an intermediate frequency (IF) signal into a 1 MHz signal and a second divider that divides a reference frequency (Ref) signal into a 1 MHz signal. 156 and a differential amplifier 152 that generates a tuning voltage Vt corresponding to a phase difference by comparing the division result of dividing the intermediate frequency IF signal with the division result of dividing the reference frequency Ref signal. Include.

The first divider 154 may convert a 447 MHz PIMD signal received from the DUT 20 into an intermediate frequency IF signal and may include a frequency deviation Δ1. The first divider 154 divides the intermediate frequency IF signal 10MHz + Δ1 into 1/10 to generate a 1MHz signal.

The second divider 156 divides the reference frequency Ref signal generated by the TCXO 160 at the same frequency as the divided signal of the first divider 154. For example, when the TCXO 160 generates a reference frequency Ref signal of 16 MHz, the second divider 156 divides the reference frequency Ref signal into 1/16 to generate a 1 MHz signal.

The differential amplifier 152 receives the divided signals of the first divider 154 and the second divider 156, generates a tuning voltage Vt corresponding to the phase difference between the two signals, and outputs the tuning voltage Vt to the VCO 140. . The 1MHz signal divided by the first divider 154 includes a frequency deviation Δ1, whereas the second divider 156 divides the reference frequency Ref signal, so that the differential amplifier 152 The tuning voltage Vt corresponding to the frequency deviation Δ1 may be generated.

4 is a flowchart of a passive element intermodulation distortion signal measuring method according to an exemplary embodiment of the present invention.

In the PIMD measurement, a frequency deviation Δ1 may occur in the received signal due to the signal generators 1 and 3 existing in the PIMD measuring apparatus (S110).

The PLL unit 150 divides the received signal having the frequency deviation Δ1 and the reference signal generated by the TCXO 160 into a divider at step S120.

The PLL unit 150 inputs the divided reference signal and the received signal to the differential amplifier 152 (S130), and in the differential amplifier 152, the tuning voltage Vt corresponding to the frequency deviation Δ1 of the divided signal. To generate (S140).

Accordingly, the VCO 140 for generating an intermediate frequency (IF) signal provides a correction frequency signal corrected according to the tuning voltage (Vt) to the mixer 110, and the mixer 110 receives the frequency deviation of the received PIMD signal ( The intermediate frequency (IF) signal may be generated by correcting Δ1 (S150).

The intermediate frequency IF signal in which the frequency deviation Δ1 is corrected is band-limited by the BPF 170 (S160). The intermediate frequency IF signal in which the frequency deviation Δ1 is corrected may coincide with the center frequency fo of the BPF 170. Thus, noise may be effectively removed through the BPF 170.

The measuring unit 180 measures the reception intensity of the PIMD signal from which the noise is removed (S170).

On the other hand, the above description illustrates the control process when measuring the PIMD signal of the remote control signal processing apparatus for processing a wireless signal of 447MHz, but this is only for the understanding of the present invention, mobile communication, short-range wireless communication, For example, the PIMD measuring apparatus of the present invention can be used in any apparatus as long as it is a wireless signal processing apparatus for processing a radio signal.

Thus, those skilled in the art will appreciate that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

The passive element intermodulation distortion signal measuring apparatus and method according to the present invention can be used to improve the measurement accuracy and to measure the received signal stably and quickly in measuring the PIMD of the radio signal processing apparatus.

1: first signal generator 3: 2nd signal generator
5: first amplifier 7: 2nd amplifier
9: power combiner 11: duplexer
20: DUT (Device Under Test) 100: Frequency correction circuit
110: mixer 120: directional coupler (DC)
130: AGC (Automatic Gain Control)
140: VCO (Voltage Control Oscillator)
150: PLL (Phase Looked Loop) unit 152: differential amplifier
154: first divider 156: second divider
160: TCXO (Temperature Compensated Crystal Oscillator)
170: BPF (Band Pass Filter) 180: measuring instrument

Claims (13)

A test signal generator for generating a test signal;
A duplexer which transmits the test signal to a device under measurement and receives an intermodulation distortion signal of the device under measurement in accordance with the test signal;
Converts the intermodulation distortion signal received by the duplexer into an intermediate frequency signal, generates a reference frequency signal to generate a tuning voltage corresponding to a phase difference with the intermediate frequency signal, and based on the tuning voltage, the intermodulation distortion signal A frequency correction circuit for outputting a correction frequency signal for correcting the phase difference of the signal and converting the intermodulation distortion signal into an intermediate frequency signal corrected for frequency drift based on the correction frequency signal;
A band limiting filter for removing noise of the intermodulation distortion signal having the drift corrected through the frequency correction circuit; And
Passive device intermodulation distortion signal measuring apparatus comprising a measuring device for measuring the intensity of the intermodulation distortion signal from which the noise is removed. The method of claim 1,
The test signal generator,
A first signal generator for generating a first frequency signal;
A second signal generator for generating a second frequency signal;
A first amplifier for amplifying the first frequency signal;
A second amplifier for amplifying the second frequency signal; And
And a power combiner configured to combine the amplified first and second frequency signals to generate a two-tone test signal. The method of claim 1,
The frequency correction circuit,
A mixer for converting the intermodulation distortion signal received from the apparatus under measurement to an intermediate frequency signal and outputting the intermediate frequency signal to the band limiting filter;
A reference frequency generator for generating a reference frequency signal;
A phase-looked loop (PLL) unit configured to generate a tuning voltage corresponding to a phase difference between the reference frequency signal and the intermediate frequency signal;
A voltage control oscillator outputting a correction frequency signal for correcting the phase difference of the intermodulation distortion signal based on the tuning voltage;
And the mixer converts the intermodulated distortion signal into an intermediate frequency signal corrected for frequency drift based on the corrected frequency signal provided by the voltage controlled oscillator. The method of claim 3,
The PLL unit,
A first divider for dividing the reference frequency signal;
A second divider for dividing the intermodulated distortion signal converted into the intermediate frequency signal into a signal having the same frequency as the first divider; and
And a differential amplifier for generating a tuning voltage corresponding to a phase difference between the divided signal of the first divider and the divided signal of the second divider. The method of claim 3,
And a directional coupler (DC) interposed in an output line of the intermediate frequency signal output from the mixer to the band limiting filter and branching an output path of the intermediate frequency signal to the PLL unit. Modulation distortion signal measuring device. The method of claim 5,
Passive element intermodulation distortion signal measuring apparatus further comprises an automatic gain regulator (AGC) interposed in the output line of the intermediate frequency signal output from the directional coupler to the PLL unit. A reference frequency signal generator for generating a reference frequency signal;
A mixer for generating an intermediate frequency signal based on the received signal from the DUT and the correction frequency signal;
A first divider for dividing the reference frequency signal, a second divider for dividing the received signal converted into the intermediate frequency signal into a signal having the same frequency as the first divider; and a divided signal of the first divider A phase-looked loop (PLL) unit including a differential amplifier for generating a tuning voltage corresponding to a phase difference between the divided signals of the second divider;
A voltage control oscillator for outputting a correction frequency signal for correcting the phase difference based on the tuning voltage;
And the mixer corrects a phase difference of the received signal based on the correction frequency signal provided by the voltage controlled oscillator. The method of claim 7, wherein
And a directional coupler (DC) interposed in the intermediate frequency signal output line of the mixer and for branching the output path of the intermediate frequency signal to the PLL unit. The method of claim 8,
And an automatic gain adjuster (AGC) interposed in the output line of the intermediate frequency signal output from the directional coupler to the PLL section. Generating a test signal and transmitting the test signal to a device under measurement;
Receiving an intermodulation distortion signal of the apparatus under test in accordance with the test signal;
Converting the received intermodulation distortion signal into an intermediate frequency signal;
Generating a reference frequency signal;
Generating a tuning voltage corresponding to a phase difference between the reference frequency signal and the intermediate frequency signal;
Outputting a correction frequency signal for correcting the phase difference of the intermodulation distortion signal based on the tuning voltage; And
Converting the intermodulated distortion signal to an intermediate frequency signal having a frequency drift corrected based on the corrected frequency signal;
Removing noise of the intermodulation distortion signal with the drift corrected; And
And measuring the strength of the intermodulated distortion signal from which the noise is removed. The method of claim 10,
Correcting the frequency drift of the intermodulation distortion signal,
And converting the intermodulated distortion signal into an intermediate frequency signal corrected for frequency drift. The method of claim 10,
Generating a tuning voltage corresponding to the phase difference between the reference frequency signal and the intermediate frequency signal,
Dividing the reference frequency signal into a first divided signal;
Dividing the intermodulated distortion signal converted into the intermediate frequency signal into a second divided signal having the same frequency as the first divided signal; And
And comparing a phase difference between the first divided signal and the second divided signal to generate a tuning voltage corresponding to the phase difference. The method of claim 12,
And amplifying the intermediate frequency signal to a size comparable with the reference frequency signal.

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