JPH0718277U - Network analyzer - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a network analyzer for measuring harmonic distortion characteristics of a fundamental wave and harmonics in a short time and performing distortion calculation processing. [Configuration] Reference oscillator 1, frequency divider 2, P. D3, S.I. G
4 and an S.4. H6, multiplier 7,
First local oscillator 8, mixer 10, second local oscillator 1
In the network analyzer having the receiving unit composed of the calculation & control unit 12 and the CRT 13, the S.R. The first BPF 9 (bandpass filter, center frequency 10 MHz) is connected in parallel between the H6 and the mixer 10.
), The second BPF 14 (bandpass filter center frequency 20
S. MHz), S.S.I.S. connected to the input side and the output side of the first BPF 9 and the second BPF 14. It consists of W15 and 16.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 It is very important to measure the transfer characteristics (gain characteristics, isolation characteristics, reflection characteristics) and harmonic distortion characteristics when evaluating the performance of an amplifier. The present invention relates to a network analyzer that measures harmonic distortion characteristics, which is one of the characteristic items for judging the quality of an amplifier, at high speed by measuring the fundamental wave and harmonics for a short time.

[0002]

[Prior art]

 Conventionally, a basic operation will be described in detail with reference to FIG. 2 in the case of measuring a harmonic distortion characteristic using a network analyzer. When the inside of the network analyzer is divided into an oscillation source unit and a reception unit, the oscillation source unit calculates the phase difference between the frequency-divided output signal of the reference oscillator 1 and the 1st IF signal supplied from the reception unit (hereinafter, referred to as a phase detector). (P.D.) 3), and the output signal is input to the signal generator 4 to form a PLL loop. The receiving section frequency-mixes the N-fold output signal of the first local oscillator 8 and the DUT output signal with a sampling head (hereinafter referred to as SH), and band-passes to obtain a predetermined frequency from the output signal. The output signal of the second local oscillator 11 is frequency-mixed by a mixer 10 through a filter (hereinafter, referred to as BPF), and the output signal is supplied to a calculation & control unit for calculation processing. , The processing result is displayed on CRT.

First, a specific example (numerical value) will be given to explain the operation when measuring the harmonic distortion characteristics. Regarding the fundamental wave measurement, S. The output signal frequency (fr) of G4 is set to 1000 MHz, for example, and input to DUT5, and the DUT5 output is connected to the test port of the network analyzer. The oscillation frequency f0 of the first local oscillator 8 inside the network analyzer is set to, for example, 50.5 MHz, and the doubled output signal is S.S. Enter in H6. An IF signal (1st IF) is created by frequency synthesis of the output signal frequency f1 × 20 = 1010 MHz of the 20th multiplication from the output of the multiplier 7 and the DUT5 output signal frequency fr = 1000 MHz. A predetermined frequency signal is extracted from the IF signal through the BPF 9 having a center frequency of 10 MHz for extracting a signal of a constant frequency and input to the mixer 10 together with the output signal frequency of the local oscillator 11 of 9.9 MHz. Further, the extracted signal is input to the arithmetic & control unit 12 to be arithmetically processed and displayed on the CRT.

In addition, the 1st IF signal from the receiving unit and the output signal of the frequency divider 2 are P.I. Input to D3. The P. The phase shift detected in D3 is S.D. It is fed back to G4 to form a phase lock loop to improve frequency stability.

Next, regarding the second harmonic measurement, the frequency of the local oscillator 8 in the above-mentioned fundamental wave measurement is changed to f1 (50.25 MHz) by the control signal from the arithmetic & control section 12. , Through the multiplier 7, S. Enter in H6. The frequency composite of the signal frequency f1 × 40 = 2010 MHz from the output of the multiplier 7 and the DUT5 output signal frequency 2 × fr = 2000 MHz is obtained. That is, for the signal passing through BPF9, f1 × 40-2 × fr = 10 MHz. The subsequent operation is the same as when measuring the fundamental wave. As described above, the fundamental wave fr is measured and stored in the memory of the arithmetic & control section 12, the harmonic 2 × fr is then measured and arithmetically processed, and the measurement result is displayed on the CRT as shown in FIG. The harmonic distortion characteristic is displayed on the CRT as shown in FIG. 4 as a result of calculating the difference between the fundamental wave fr and the harmonic wave 2 × fr.

[0006]

[Problems to be solved by the device]

 The problems that must be solved in the conventional measurement method as shown in FIG. 2 are as follows. At each measurement frequency point, when the fundamental wave measurement is completed and the process moves to the harmonic measurement, the frequency setting of the first local oscillator 8 must be switched from 50.5 MHz to 50.25 MHz. When this switching is performed, it takes time for the first local oscillator 8 to stabilize. Also, in order to improve the accuracy, it is necessary to increase the measurement frequency point, and it takes a lot of time. In addition, there is a drawback that the strain characteristics cannot be seen unless the measurement is completed.

[0007]

[Means for solving problems]

 In order to improve this problem, the following configuration is adopted. The phase difference between the frequency-divided output signal of the reference oscillator 1 and the IF signal supplied from the receiving unit is P.P. The frequency mixing is performed between the oscillation source section, which is detected by D3, and the output signal is input to the signal generator 4 to form a PLL loop, the N multiplication signal of the first local oscillator 8 and the DUT output signal. S. H 6, a mixer 10 to which the output signal of the second local oscillator 11 is input, a calculation & control unit 12 for calculating and storing the output signal of the mixer 10, and a CRT 13 for displaying the result after the calculation process. In a network analyzer having a dual heterodyne detection receiver configured, the S. Between the H6 and the mixer 10, at the time of measuring the fundamental signal and the harmonic signal, the switches 15 and 16 controlled by the calculation & control unit signal are provided on the input side and the output side, and the center frequencies are different. A network analyzer with parallel BPFs.

[0008]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. The reference oscillator 1, the frequency divider 2 that divides the output signal frequency of the reference oscillator 1 by 1 / N, and the phase difference between the output signal of the frequency divider 2 and the 1st IF signal supplied from the network analyzer are detected. Issue P. D3 and the P. An oscillation source section composed of a signal generator 4 for inputting an output signal of D3 to form a PLL loop, an input port for receiving an output signal of DUT5, a first local oscillator 8, and the first local oscillator 8 (1st Local) ) Multiplying the output signal frequency by N, mixing the frequency of the multiplier 7, the input signal and the multiplier signal. H6 and first BPF 9 and second BPF 14 having different input and output center frequencies and switches 15 and 16 for switching at the time of measurement of the fundamental wave and the harmonic signal are arranged in two stages in parallel, the first BPF 9 and the second BPF 14. And a mixer for receiving the output of the second local oscillator 11 (2nd Local) as an input, and the operation and control for calculating the output of the mixer 10 and controlling the switch and the signal generator in the oscillation source section. It is composed of a section 12 and a CRT 13 for displaying the result after the arithmetic processing.

The operation principle will be described. First, when measuring the fundamental wave fr (1000 MHz), S. The frequency of G4 is set to 1000 MHz and input to the DUT (amplifier), and the output signals fr, 2 × fr ... The signal obtained by multiplying the output signal of the first local oscillator 8 (50.5 MHz) by the S. Input to H6 and synthesize the frequency. At this time, S. W15 and W16 are set in the path connected to the first BPF 9 by the control signal from the operation & control unit 12 and the signal of the predetermined intermediate frequency 1st IF (10 MHz) is extracted through the first BPF 9 having the center frequency 10 MHz and the first signal is extracted. It is input to the mixer 10 together with the output signal of the two local oscillator 11 (15 MHz). Here, the output signal frequency of the second local oscillator (2nd Local) is obtained by the sum of 1st IF and 1st IF / 2. 1st IF in this case is the 1st IF signal frequency at the time of fundamental wave measurement. After being input to the mixer 10, frequency synthesis is performed and a final IF signal of 5 MHz is output.

Next, when measuring harmonics 2 × fr (1000 MHz), the output signal of the first local oscillator 8 (50.5 MHz) is fixed, and S.S. A signal of a predetermined intermediate frequency 1 st IF (20 MHz) is extracted through the second BPF 14 having a center frequency of 20 MHz, which is set by the control signal from the arithmetic & control unit 12 on the path where W15 and W16 are connected to the second BPF 14. . Further, through the mixer 10, frequency synthesis is performed and a final IF signal of 5 MHz is output. The final IF signal is input to the arithmetic & control section, and the data is stored in the memory when the fundamental wave is measured. When the data for the next harmonic measurement is input, it is calculated with the fundamental wave data measured previously to obtain harmonic distortion data, which is displayed on the CRT 13.

[0011]

[Effect of device]

 As described above, according to the apparatus of the present invention, the frequency of the local oscillator 8 is fixed without changing as compared with the conventional measuring method, and the S. Since only W15 and W16 are switched, extremely high-speed processing can be performed. Furthermore, since a network analyzer usually has a plurality of receivers (generally 3 inputs), the S. If W15 and W16 are set to the path connected to the first BPF 9 and the reverse path connected to the second BPF 14, the fundamental wave and harmonics can be measured in a short time as shown in FIGS. The frequency characteristics of distortion characteristics can be displayed by high-speed calculation processing with.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional example.

FIG. 3 is a graph showing the fundamental wave and second harmonic frequency characteristics of the present embodiment.

FIG. 4 is a graph showing the harmonic distortion characteristics of this example.

[Explanation of symbols]

1 reference oscillator 2 minute period 3 P. D (Phase detector) 4 S.I. G (signal generator) 5 DUT (amplifier) 6 S.I. H (sampling head) 7 multiplier 8 first local oscillator (1st Local) 9 BPF (bandpass filter intermediate frequency 10 MH
z) 10 mixer (frequency mixer) 11 second local oscillator (2nd Local) 12 arithmetic & control unit 13 CRT (display unit) 14 BPF (bandpass filter intermediate frequency 20 MH)
z) 15, 16 S.I. W

Claims (1)

[Scope of utility model registration request] 1. A configuration in which a phase difference between a frequency-divided output signal of a reference oscillator and an IF signal supplied from a receiving unit is detected by a phase detector and the output signal is input to a signal generator to form a PLL loop. A source for oscillation, a sampling head for frequency-mixing the N-multiplied signal of the first local oscillator and the DUT output signal, a mixer to which the output signal of the second local oscillator is input, and calculation of the mixer output signal A CR that automatically controls each part local by the signal from the calculation & control part to be processed and stored and displays the result after the calculation process.
In a network analyzer having a dual heterodyne detection receiver configured with T, control is performed between the sampling head and the mixer by a signal emitted from a calculation & control unit during measurement of a fundamental signal and measurement of a harmonic signal. A network analyzer that has a plurality of band-pass filters with different center frequencies and that have switches for input and output.