Circuit characteristic measuring system and circuit characteristic measuring method

Abstract

The present invention provides a circuit characteristic measuring system and a circuit characteristic measuring method, wherein the circuit characteristic measuring system (1) comprises: a signal voltage generating circuit (2) for sequentially applying a plurality of periodic voltage signals to a circuit under test (51) of a measuring object, wherein the plurality of periodic voltage signals respectively have a predetermined reference frequency and a frequency that is an integer multiple of the reference frequency; a measuring circuit (3) for sequentially measuring the power of a signal generated in the circuit under test (51) due to sequentially applying the periodic voltage signals to the circuit under test (51); and a transfer function calculating unit (42) for calculating transfer functions H and H2 of the circuit under test (51) based on a plurality of powers measured by the measuring circuit (3) using a predetermined formula, wherein the periodic voltage signal includes a high-order frequency component.

Description

[0001] This application is based on Japanese patent application No. 2019-176576 filed on September 27, 2019, and the contents are incorporated herein by reference. Technical Field

[0002] The present invention relates to a circuit characteristic measuring system and a circuit characteristic measuring method for measuring characteristics of a circuit. Background Art

[0003] There has been a method for measuring the power supply impedance of an on-chip power supply node (for example, see Non-Patent Document 1). According to Non-Patent Document 1, a current source is used to flow a rectangular wave current from the current source to the power supply node by sinking, and the effective power on the power supply node is measured. Based on the effective power, the power supply impedance of the power supply node can be measured.

[0004] Prior art literature

[0005] Non-patent literature

[0006] Non-patent document 1: A Technique for Analyzing On-chip Power Supply Impedance, 2015 IEEE 24th Asian Test Symposium, Masahiro Ishida, Toru Nakura, Akira Matsukawa, Rimon Ikeno, and Kunihiro Asada Summary of the invention

[0007] In addition, a current source circuit capable of passing a rectangular wave current is required in Non-Patent Document 1. However, it is not easy to realize a current source circuit capable of performing current control to pass a rectangular wave current, and even if realized, it is expensive.

[0008] An object of the present invention is to provide a circuit characteristic measuring system and a circuit characteristic measuring method which can measure the characteristics of a circuit to be measured without using a current source circuit for current control of flowing a rectangular wave current.

[0009] A circuit characteristic measurement system of an example of the present invention includes: a signal voltage generating circuit, which sequentially applies a plurality of periodic voltage signals to a circuit under test of a measurement object, wherein the plurality of periodic voltage signals respectively have a specified reference frequency and a frequency that is an integer multiple of the reference frequency; a measurement circuit, which sequentially measures the power of a signal generated in the circuit under test due to sequentially applying the periodic voltage signals to the circuit under test; and a transfer function calculation unit, which uses a predetermined formula to calculate the transfer function of the circuit under test based on the power measured by the measurement circuit, wherein the periodic voltage signal includes a high-order frequency component.

[0010] In addition, a circuit characteristic measuring method of an example of the present invention includes: a signal voltage application step, in which a plurality of periodic voltage signals are sequentially applied to a circuit under test of a measuring object, wherein the plurality of periodic voltage signals respectively have a specified reference frequency and a frequency that is an integer multiple of the reference frequency; a measuring step, in which the power of a signal generated in the circuit under test due to application of the periodic voltage signal to the circuit under test is respectively measured; and a transfer function calculation step, in which a transfer function of the circuit under test is calculated based on a plurality of powers measured by the measuring circuit using a predetermined formula, wherein the periodic voltage signal includes a high-order frequency component. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a block diagram showing an example of the configuration of a circuit characteristic measurement system using the circuit characteristic measurement method according to one embodiment of the present invention.

[0012] Figure 2 : is a flowchart showing an example of the operation of the circuit characteristic measurement system 1 .

[0013] Figure 3 This is an explanatory diagram for explaining a method of measuring characteristics of a circuit portion related to measurement of a transfer function.

[0014] Figure 4 2 is a waveform diagram showing an example of a periodic voltage signal output from the signal voltage generating circuit 2a.

[0015] Figure 5 This is a flowchart showing an example of a method for measuring characteristics of a circuit portion related to measurement of a transfer function.

[0016] Figure 6 1 is a flowchart showing an example of the operation of the circuit characteristic measurement system 1 a using a periodic voltage signal other than a rectangular wave.

[0017] Figure 7 This is a waveform diagram showing an example of a periodic voltage signal having a symmetrical waveform.

[0018] Figure 81 is a flowchart showing an example of the operation of the circuit characteristic measuring system 1 b using a periodic voltage signal having a symmetrical waveform.

[0019] Fig. 9 This is a waveform diagram showing an example of an ideal trapezoidal waveform.

[0020] [Explanation of Symbols]

[0021] 1. 1a, 1b: Circuit characteristics measurement system

[0022] 2, 2a, 2b: Signal voltage generating circuit

[0023] 3: Measurement circuit

[0024] 4, 4a, 4b: Control unit

[0025] 5: Substrate

[0026] 6: Spectrum Analyzer

[0027] 21: Oscillator circuit

[0028] 22: Clock Buffer

[0029] 41, 41a, 41b: Measurement control unit

[0030] 42, 42a, 42b: Transfer function calculation unit

[0031] 43: Storage

[0032] 51: Circuit under test

[0033] A. A (mn)m :power

[0034] B.B (mn)m : Peak

[0035] C: Axis of symmetry

[0036] H.H 2 : Transfer function

[0037] H m : Signal attenuation rate

[0038] H(mf0),H 2 (mf0): transfer function

[0039] P, P F1 , P F2 , P F3 , P(mf0): signal power

[0040] Po, Pi: Probe

[0041] P T1 , PT2 , P T3 :power

[0042] T: Period

[0043] T1, T2: terminals

[0044] V F1 (t), V F2 (t), V F3 (t): signal

[0045] V T1 (t), V T2 (t), V T3 (t): periodic voltage signal

[0046] f0: reference frequency

[0047] m: variable

[0048] mf0: base frequency

[0049] n: number of times

[0050] t: time axis

[0051] τ f : Fall time

[0052] τ r : Rise time DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same reference numerals in the drawings denote the same structures, and their descriptions are omitted. Figure 1 The circuit characteristic measuring system 1 shown includes a signal voltage generating circuit 2, a measuring circuit 3, a control unit 4, a plurality of probes Po for signal output, and a plurality of probes Pi for signal measurement.

[0054] For example, a plurality of circuits 51 to be measured are formed on one substrate 5. The circuits 51 to be measured may be, for example, filter circuits, circuit boards, transmission paths, or other circuits having electrical characteristics. Each circuit 51 to be measured includes terminals T1 and T2.

[0055] The plurality of circuits under test 51 may be formed by collecting a plurality of identical circuits on one substrate 5 in the form of an aggregate substrate, or may form different circuits under test 51 on one substrate 5. In addition, the plurality of circuits under test 51 are not limited to being formed on one substrate 5, but may be formed independently.

[0056] The signal voltage generating circuit 2 sequentially applies a plurality of periodic voltage signals to the measured circuit 51 of the measured object according to the control signal from the control unit 4, and the plurality of periodic voltage signals respectively have a predetermined reference frequency and a frequency m times (m is an integer) of the reference frequency. The signal voltage generating circuit 2 includes an oscillation circuit 21 and a clock buffer 22. Each periodic voltage signal is a signal including a frequency component of its own fundamental wave and a frequency component that is an integer multiple of 2 or more of the fundamental wave, i.e., a higher-order frequency component.

[0057] The oscillation circuit 21 outputs a periodic voltage signal of a frequency corresponding to the control signal from the control unit 4 to the clock buffer 22. As the oscillation circuit 21, for example, a voltage controlled oscillator (VCO) can be used. Furthermore, the oscillation circuit 21 can be combined with a frequency dividing circuit to expand the frequency variation range.

[0058] The clock buffer 22 is a signal output circuit that shapes the periodic voltage signal output from the oscillation circuit 21 into a rectangular wave, distributes it, and outputs it to a plurality of probes Po. Thus, a rectangular wave periodic voltage signal is output from the signal voltage generating circuit 2 .

[0059] When measuring, each probe Po is used by contacting the terminal T1 of each circuit under test 51, and each probe Pi is used by contacting the terminal T2 of each circuit under test 51. Thus, the periodic voltage signal distributed and outputted from the clock buffer 22 is applied to the terminal T1 of each circuit under test 51 via each probe Po, and is outputted to the terminal T2 through each circuit under test 51.

[0060] The measuring circuit 3 sequentially measures the power of the signal generated in the measured circuit 51 due to the sequential application of the periodic voltage signal to the measured circuit 51 according to the control signal from the control unit 4. As the measuring circuit 3, for example, various general-purpose integrated circuits (ICs) capable of measuring RMS power, such as the root mean square (RMS) power detector LTC5596 manufactured by Analog Devices and the ADL5904 manufactured by Analog Devices, can be used.

[0061] The number of the periodic voltage signals distributed and outputted from the clock buffer 22 is the same as the number of the probes Po, that is, the measurement circuits 3 and the probes Pi are provided.

[0062] Each measuring circuit 3 acquires a signal from the terminal T2 of each measured circuit 51 via each probe Pi, and measures the effective power thereof. Each measuring circuit 3 outputs a signal indicating the measured effective power to the control unit 4 .

[0063] By including the clock buffer 22 and the plurality of measurement circuits 3, the circuit characteristic measurement system 1 can measure the characteristics of the plurality of measured circuits 51 in parallel. Thus, the measurement time can be shortened. Furthermore, the circuit characteristic measurement system 1 does not necessarily need to include the clock buffer 22 and the plurality of measurement circuits 3. It may also be configured as follows: a buffer circuit for shaping the waveform into a rectangular wave is included instead of the clock buffer 22, and the measurement circuit 3 is set to one, and the characteristics of the measured circuits 51 are measured one by one.

[0064] The control unit 4 is composed of, for example, a central processing unit (CPU), a random access memory (RAM), a non-volatile storage unit 43 and their peripheral circuits, wherein the CPU performs prescribed calculations, the RAM temporarily stores data, and the non-volatile storage unit 43 is a flash memory or a hard disk drive (HDD) that stores a prescribed control program.

[0065] The control unit 4 functions as the measurement control unit 41 and the transfer function calculation unit 42 by executing a control program stored in the storage unit 43 , for example.

[0066] The measurement control unit 41 outputs a control signal to the signal voltage generating circuit 2, causing the signal voltage generating circuit 2 to output a periodic voltage signal of a predetermined frequency. Thus, a periodic voltage signal of a predetermined frequency is applied to the terminal T1 of each measured circuit 51. In addition, while the signal voltage generating circuit 2 is outputting the periodic voltage signal of the predetermined frequency, the measurement control unit 41 measures the power of the signal output from the terminal T2 through each measurement circuit 3.

[0067] The measurement control unit 41 associates the power measured by each measurement circuit 3 with the frequency output from the signal voltage generating circuit 2 and stores them in, for example, the storage unit 43. Thereafter, the measurement control unit 41 repeats the output of the periodic voltage signal by the signal voltage generating circuit 2 and the power measurement by each measurement circuit 3 while changing the frequency, and associates the measured power with the frequency and stores them in the storage unit 43, etc.

[0068] The transfer function calculation unit 42 uses a preset formula to calculate the transfer function of each circuit under test 51 based on the multiple powers measured by the measurement circuit 3. As the preset formula, for example, a formula obtained by Fourier series expansion of the periodic voltage signal can be used. As the formula obtained by Fourier series expansion of the periodic voltage signal, the formula (1), formula (1)', formula (2), formula (2)', formula (3) or formula (3)' described later can be used.

[0069] Next, the operation of the circuit characteristic measurement system 1 configured as described above will be described. In the following flowcharts, the same processing is denoted by the same step number and the description thereof may be omitted.

[0070] Reference Figure 2 , the measurement control unit 41 initializes the variable m to 1 (step S1). Next, the measurement control unit 41 outputs a control signal to the signal voltage generating circuit 2, causing the signal voltage generating circuit 2 to output a periodic voltage signal of the reference frequency mf0 and apply it to each circuit under test 51 (step S2).

[0071] In this way, the power of the signal after passing through each measured circuit 51 is measured in the form of P(mf0) in each measuring circuit 3, and a signal indicating the measured value is output to the control unit 4 (step S3). The measurement control unit 41 associates the signal power P(mf0) obtained from each measured circuit 51 with the frequency mf0 and stores them in the storage unit 43, etc. (step S4).

[0072] Next, the measurement control unit 41 compares the variable m with 7 (step S5). If the variable m is less than 7 (No in step S5), 2 is added to the variable m to change the frequency of the periodic voltage signal and continue the measurement (step S6), and steps S2 to S5 are repeated again.

[0073] In this way, a periodic voltage signal of the reference frequency 3f0 is applied to each circuit under test 51 (step S2), the signal power P(3f0) is measured in each measuring circuit 3 (step S3), and the signal power P(3f0) of each circuit under test 51 is associated with the frequency 3f0 and stored (step S4).

[0074] Steps S2 to S6 are repeated until the variable m in step S5 becomes, for example, 7. As a result, the signal powers P(f0), P(3f0), P(5f0), and P(7f0) of the respective circuits under test 51 are associated with the reference frequencies f0, 3f0, 5f0, and 7f0 and stored in the storage unit 43 or the like.

[0075] When the variable m becomes 7 (Yes in step S5), the transfer function calculation unit 42 substitutes P(f0), P(3f0), P(5f0), and P(7f0) into the following equation (1)' for each circuit under test 51, and calculates the transfer function H of each circuit under test 51. 2 (f0),H 2 (3f0),H 2 (5f0),H 2 (7f0)(Step S7).

[0076] [Formula 4]

[0077]

[0078] Among them, B is the peak voltage of the periodic voltage signal (rectangular wave) output from the signal voltage generating circuit 2, and A is the effective value power of the periodic voltage signal.

[0079] Transfer function H 2 (f0),H 2 (3f0),H 2 (5f0),H 2 (7f0) represents the characteristic of the measured circuit 51, so by calculating the transfer function H 2 (f0),H 2 (3f0),H 2 (5f0),H 2 (7f0), the characteristics of the measured circuit 51 can be measured. Furthermore, the transfer function H can also be obtained. 2 (f0),H 2 (3f0),H 2 (5f0),H 2 The transfer functions H(f0), H(3f0), H(5f0), and H(7f0) are calculated as the circuit characteristics by taking the square root of (7f0). Among them, H is the amplitude transfer function and does not contain phase information.

[0080] Figure 1 The signal voltage generating circuit 2 shown outputs a rectangular wave voltage signal as a periodic voltage signal. To generate a rectangular wave voltage, it is sufficient to switch a DC voltage by a switching element, and a commercially available semiconductor element such as a clock buffer 22 or a buffer can be used to easily generate a periodic voltage signal. Therefore, according to the circuit characteristic measuring system 1, a rectangular wave voltage signal can be output as a periodic voltage signal to measure the characteristics of the measured circuit 51 without using a current source circuit that controls the current flowing a rectangular wave current.

[0081] In addition, the periodic voltage signal can be distributed to multiple circuits under test 51 through the clock buffer 22 and the power of the signal after passing through each circuit under test 51 can be measured in parallel through multiple measurement circuits 3. Therefore, the measurement time can be shortened compared with the case where the characteristics of the circuits under test 51 are measured one by one.

[0082] Furthermore, the present invention is not limited to applying four periodic voltage signals of frequencies f0, 3f0, 5f0, and 7f0 and measuring the signal powers P(f0), P(3f0), P(5f0), and P(7f0) to calculate the transfer function H of the four parameters. 2 (f0),H 2 (3f0),H 2 (5f0),H 2The frequency of the applied periodic voltage signal may be set to five or more (f0, 3f0, 5f0, 7f0, 9f0, ...), the -1th power matrix in equation (1) may be set to 5×5 or more, and the number of parameters of the transfer function may be set to five or more (H 2 (f0),H 2 (3f0),H 2 (5f0),H 2 (7f0),H 2 (9f0)···).

[0083] By increasing the number of transfer function parameters, the circuit characteristics of the measured circuit 51 can be measured with higher accuracy. On the other hand, when the number of transfer function parameters is increased, the measurement takes longer and the amount of calculation processing also increases. Therefore, the number of transfer function parameters to be calculated can be appropriately determined based on the balance between the required measurement accuracy of the circuit characteristics and the measurement time or the amount of calculation processing.

[0084] In addition, the periodic voltage signal does not necessarily have to be a rectangular wave, as long as it is a periodic waveform that includes a high-order frequency component and changes periodically. When a periodic waveform other than a rectangular wave is used as the periodic voltage signal, the characteristics of the circuit part related to the measurement of the transfer function in the circuit characteristic measurement system 1 must be measured in advance.

[0085] Reference Figure 3 When measuring the characteristics of the circuit part related to the measurement of the transfer function, the spectrum analyzer 6 is used instead of the measurement circuit 3. The difference between the signal voltage generating circuit 2a and the signal voltage generating circuit 2 is that the periodic voltage signal output from the signal voltage generating circuit 2a does not necessarily have to be a rectangular wave. The periodic voltage signal output from the signal voltage generating circuit 2a can be a periodic waveform that changes periodically, and its signal waveform is not limited.

[0086] like Figure 4 As shown, the periodic voltage signal output from the signal voltage generating circuit 2a may be, for example, a signal having an asymmetrical waveform in which the rising slope and the falling slope are different.

[0087] The measurement control unit 41a is different from the measurement control unit 41 in that it also performs processing for measuring the characteristics of the circuit portion related to the measurement of the transfer function. The transfer function calculation unit 42a is different from the transfer function calculation unit 42 in that the transfer function of the measurement circuit 3 is calculated using equations (2)' and (2) instead of equations (1)' and (1).

[0088] First, the characteristics of a pair of probes Po and Pi connected to the first circuit under test 51 are measured. Figure 5, the probe Pi connected to the first circuit to be measured 51 is connected to the spectrum analyzer 6, and the probe Po that forms a pair with the probe Pi is brought into contact with the probe Pi (step S11).

[0089] Next, the measurement control unit 41a initializes the variable m to 1 (step S12). m is a natural number (1, 2, 3, ...). Next, the measurement control unit 41a outputs a control signal to the signal voltage generating circuit 2a, causing the signal voltage generating circuit 2a to output a periodic voltage signal of the reference frequency mf0 to the probe Po (step S13). In this way, the periodic voltage signal is input to the spectrum analyzer 6 via the probes Po and Pi.

[0090] Next, the spectrum analyzer 6 measures the power A of the fundamental wave and its harmonics included in the signal input to the spectrum analyzer 6 via the probes Po and Pi. (mn)m , and stored in the storage unit 43 (step S14). n is the order of the higher harmonic relative to the fundamental wave, and when n=1, it represents the fundamental wave itself. The power A when n=1 (m×1)m The power A represents the effective value power of the fundamental wave having a frequency m times the reference frequency f0, when n is 3 or more. (mn)m It represents the effective value power of the nth harmonic relative to the fundamental wave having a frequency m times the reference frequency f0. Similarly, the peak value B when n=1 (m×1)m The peak voltage of the fundamental wave having a frequency m times the reference frequency f0 is represented by the peak value B (mn)m Indicates the peak voltage of the nth harmonic with respect to the fundamental wave having a frequency m times the reference frequency f0.

[0091] Specifically, when m=1, the power A of the fundamental wave (n=1) is measured. (1×1)1 , the power of the second harmonic (n = 2) A (1×2)1 , power A of the third harmonic (n=3) (1×3)1 , the power of the fourth harmonic (n=4) A (1×4)1 , the power of the fifth harmonic (n=5) A (1×5)1 , the power of the sixth harmonic (n=6) A (1×6)1 ···. When m=2, measure the power A of the fundamental wave (n=1) (2×1)2 , the power of the second harmonic (n = 2) A (2×2)2 , power A of the third harmonic (n=3) (2×3)2 ···. When m=3, measure the power A of the fundamental wave (n=1) (3×1)3 , the power of the second harmonic (n = 2) A (3×2)3 ... The number of m to several and the number of higher harmonics (n to several) to measure power may be appropriately determined according to the required measurement accuracy of circuit characteristics.

[0092] For example, the power A thus determined can be (mn)m The spectrum analyzer 6 sends the signal to the control unit 4 and stores the signal in the storage unit 43. For example, the power A (mn)m The spectrum analyzer 6 is stored in a storage medium such as a memory card or a USB memory, and the control unit 4 reads the storage medium and stores it in the storage unit 43 . Alternatively, the storage medium may be directly used as a part of the storage unit 43 .

[0093] Next, the measurement control unit 41 compares the variable m with 7 (step S15). When the variable m is less than 7 (No in step S15), 1 is added to the variable m to change the frequency of the periodic voltage signal and continue the measurement (step S16), and steps S13 to S15 are repeated again.

[0094] Repeat steps S13 to S16 until the variable m in step S15 becomes 7, thereby determining the power A corresponding to m=1 to 7. (mn)m That is, data indicating characteristics of the circuit portion related to the measurement of the transfer function is stored in the storage unit 43 .

[0095] Furthermore, in steps S5, S15 and steps S23 and S33 described later, the upper limit of m may be appropriately determined according to the required measurement accuracy of the circuit characteristics. The upper limit of m, that is, the number of types of reference frequencies of the periodic voltage signal, is consistent with the maximum order of higher harmonics measured for the periodic voltage signal with m=1.

[0096] Thereafter, steps S11 to S16 are sequentially performed on the remaining probe pairs Po and Pi.

[0097] Next, a method for measuring the characteristics of the measurement circuit 3 using a periodic voltage signal other than a rectangular wave will be described. A circuit characteristic measurement system 1a capable of measuring the characteristics of the measurement circuit 3 using a periodic voltage signal other than a rectangular wave is Figure 1 The symbols are indicated by brackets.

[0098] The circuit characteristic measurement system 1a is different from the circuit characteristic measurement system 1 in that it includes a signal voltage generation circuit 2a, a control unit 4a, a measurement control unit 41a, and a transfer function calculation unit 42a instead of the signal voltage generation circuit 2, the control unit 4, the measurement control unit 41, and the transfer function calculation unit 42. (mn)m And stored in the storage unit 43 of the control unit 4a.

[0099] Reference Figure 6, the measurement control unit 41a initializes the variable m to 1 (step S21). Next, the measurement control unit 41a outputs a control signal to the signal voltage generating circuit 2a, causing the signal voltage generating circuit 2a to output a periodic voltage signal of the reference frequency mf0 and apply it to each circuit under test 51 (step S22).

[0100] In this way, the power of the signal after passing through each measured circuit 51 is measured in the form of P(mf0) in each measuring circuit 3, and a signal indicating the measured value is output to the control unit 4a (step S3). The measurement control unit 41a associates the signal power P(mf0) obtained from each measured circuit 51 with the frequency mf0 and stores them in the storage unit 43, etc. (step S4).

[0101] Next, the measurement control unit 41a compares the variable m with, for example, 6 (step S23). When the variable m is less than 6 (No in step S23), 1 is added to the variable m to change the frequency of the periodic voltage signal and continue the measurement (step S24), and steps S22 to S23 are repeated again. Steps S22 to S24 are repeated until the variable m becomes 6 in step S23, whereby, as in steps S1 to S6, the signal powers P(f0) to P(6f0) of each circuit under test 51 are associated with the reference frequencies f0 to 6f0 and stored in the storage unit 43, etc.

[0102] When the variable m becomes 6 (Yes in step S23), the transfer function calculation unit 42a substitutes P(f0) to P(6f0) into the following equation (2)' for each circuit 51 to be measured, and calculates the power A in advance stored in the storage unit 43. (mn)m The transfer function H of each circuit under test 51 is calculated. 2 (f0)~H 2 (6f0)(Step S25).

[0103] [Formula 5]

[0104]

[0105] As described above, according to steps S21 to S25, even when a periodic voltage signal other than a rectangular wave is used, the transfer function H representing the characteristics of each circuit under test 51 can be measured. 2 (f0)~H 2 (6f0). Furthermore, we can also find the transfer function H 2 (f0)~H 2 The transfer functions H(f0) to H(6f0) are calculated as the circuit characteristics by taking the square root of (6f0).

[0106] According to the circuit characteristic measurement system 1a and steps S21 to S25, the characteristics of the circuit 51 under test can be measured even when it is difficult to apply a rectangular wave periodic voltage signal to the circuit 51 under test due to the performance of the clock buffer 22, the impedance of the probes Po and Pi, the stray capacitance of the circuit, etc.

[0107] In addition, when a periodic voltage signal having a waveform such as: Figure 7 As shown, a symmetry axis C perpendicular to the time axis t is arranged at a point on the time axis t in the signal waveform of one period T, thereby being symmetrical with respect to the symmetry axis C. Figure 7 The periodic voltage signal shown is, for example, a trapezoidal wave in which the rising and falling inclinations are equal.

[0108] Figure 1 The circuit characteristic measuring system 1b indicated by brackets in the figure is different from the signal voltage generating circuit 2a and the control unit 4a in the configuration of the signal voltage generating circuit 2b and the control unit 4b. The signal voltage generating circuit 2b outputs a periodic voltage signal with a symmetrical waveform.

[0109] The measurement control unit 41b is different from the measurement control unit 41a in the following respects. The measurement control unit 41b does not perform power A for harmonics whose order n is an even number in step S14. (mn)m In addition, the measurement control unit 41b does not perform the power A when m is an even number by adding 2 to m in step S16. (mn)m In addition, the measurement control unit 41b uses the equation (3)' described later instead of the equation (2)'.

[0110] Reference Figure 8 , the measurement control unit 41b initializes the variable m to 1 (step S31). Next, the measurement control unit 41b outputs a control signal to the signal voltage generating circuit 2b, causing the signal voltage generating circuit 2b to output a periodic voltage signal of the reference frequency mf0 and apply it to each circuit under test 51 (step S32).

[0111] In this way, the power of the signal after passing through each measured circuit 51 is measured in the form of P(mf0) in each measuring circuit 3, and a signal indicating the measured value is output to the control unit 4b (step S3). The measurement control unit 41b associates the signal power P(mf0) obtained from each measured circuit 51 with the frequency mf0 and stores them in the storage unit 43, etc. (step S4).

[0112] Next, the measurement control unit 41b compares the variable m with 7 (step S33). If the variable m is less than 7 (No in step S33), 2 is added to the variable m to change the frequency of the periodic voltage signal and continue the measurement (step S34), and steps S32 to S33 are repeated again.

[0113] According to step S34, the periodic voltage signal having the reference frequency mf0 when the variable m is an even number is not output in step S32, and the signal power P(mf0) when the variable m is an even number is not measured or stored in steps S3 and S4.

[0114] As described above, steps S31 to S34 are repeated until the variable m in step S33 becomes 7. Thus, as in steps S1 to S6, the signal powers P(f0), P(3f0), P(5f0), and P(7f0) of each measured circuit 51 are associated with the reference frequencies f0, 3f0, 5f0, and 7f0 and stored in the storage unit 43, etc.

[0115] When the variable m becomes 7 (Yes in step S33), the transfer function calculation unit 42b substitutes P(f0), P(3f0), P(5f0), and P(7f0) into the following equation (3)' for each circuit under test 51, and calculates the power A in advance stored in the storage unit 43. (mn)m The transfer function H of each circuit under test 51 is calculated. 2 (f0),H 2 (3f0),H 2 (5f0),H 2 (7f0)(Step S35).

[0116] [Formula 6]

[0117]

[0118] Furthermore, we can also find the transfer function H 2 (f0),H 2 (3f0),H 2 (5f0),H 2 The transfer functions H(f0), H(3f0), H(5f0), and H(7f0) are calculated as the circuit characteristics by taking the square root of (7f0).

[0119] According to the above steps S31 to S35, the transfer function H of each circuit under test 51 can be calculated when a periodic voltage signal with a symmetrical waveform is used. 2 (f0),H 2 (3f0),H 2 (5f0),H 2(7f0) In addition, since it is not necessary to measure the signal power P(mf0) when m is an even number in step S3, the terms with an even number of times can be reduced in equation (3)' in step S35, so the processing can be simplified compared with steps S21 to S25.

[0120] Furthermore, in Figure 1 In the circuit characteristic measuring systems 1, 1a, and 1b shown, an example is shown in which the probe Pi is brought into contact with the terminal T2, and the power of the transmitted wave formed by the periodic voltage signal passing through the measured circuit 51 is measured in the measuring circuit 3. However, the probe Pi may be brought into contact with the terminal T1, and the power of the reflected wave formed by the periodic voltage signal reflecting in the measured circuit 51 may be measured in the measuring circuit 3. In the case of measuring the reflected wave, the reflection characteristic, i.e., the transfer function of the reflected wave may be measured by the measuring circuit 3 through the same processing as steps S1 to S7, S11 to S16, S21 to S25, and S31 to S35.

[0121] In addition, the transfer function calculation units 42, 42a, 42b are not necessarily limited to the example of using the equations (1)', (2)', (3)' themselves in steps S7, S25, S35. The transfer function calculation units 42, 42a, 42b only need to perform the calculations shown in the equations (1)', (2)', (3)' in steps S7, S25, S35, and, for example, may calculate the equations obtained by expanding the equations (1)', (2)', (3)'.

[0122] Next, the case where equations (1), (1)', (2), (2)', (3), (3)' are equations obtained by Fourier series expansion of the periodic voltage signal is described. Furthermore, equations (1), (2), (3) are equivalent to simplified expressions of the same equations as equations (1)', (2)', (3)'.

[0123] The following formula (A) is a formula that expresses the periodic voltage signal of the reference frequency f0 as a Fourier series expansion, formula (B) is a formula that expresses the periodic voltage signal of the reference frequency 2f0 as a Fourier series expansion, and formula (C) is a formula that expresses the periodic voltage signal of the reference frequency 3f0 as a Fourier series expansion.

[0124] [Formula 7]

[0125]

[0126] B (1n)1 Indicates the peak value of the nth harmonic component at the reference frequency f0, B (2n)2 Indicates the peak value of the nth harmonic component at the reference frequency 2f0, B (3n)3 Indicates the peak value of the nth harmonic component at the reference frequency 3f0, ω=2πf.

[0127] e in formula (A), (B), (C) jθ The absolute value of this term is 1, and the periodic voltage signal V T1 (t), V T2 (t), V T3 (t) Power P T1 , P T2 , P T3 It can be represented by the following formulas (D), (E), and (F).

[0128] [Formula 8]

[0129]

[0130]

[0131] Here, P = VI, P = V 2 / R. Therefore, the power P shown in equations (D), (E), and (F) T1 , P T2 , P T3 To be precise, it is a value obtained by dividing by the characteristic impedance R (eg, 50Ω) of the circuit 51 under test, but the characteristic impedance R is omitted in the equations (D), (E), and (F).

[0132] Next, if the signal attenuation rates of frequencies 1f0, 2f0, 3f0, ..., mf0 are set to H1, H2, H3, ..., H m , then the signal V after the periodic voltage signal of frequency 1f0, 2f0, 3f0 passes through the measured circuit 51 F1 (t), V F2 (t), V F3 (t) is represented by the following formula (G), (H) and (I).

[0133] [Formula 9]

[0134]

[0135] Signal V F1 (t), V F2 (t), V F3 (t) Power P F1 (=P(f0)),P F2 (=P(2f0)),P F3 (=P(3f0)) is represented by the following formulas (J), (K) and (L).

[0136] [Formula 10]

[0137]

[0138] When equations (J), (K), and (L) are expressed using a matrix, the following equation (M) is obtained.

[0139] [Formula 11]

[0140]

[0141] By transforming the equation (M), we can obtain equations (2) and (2)'. Therefore, equations (2) and (2)' are nothing more than equations obtained by performing Fourier series expansion on the periodic voltage signal.

[0142] Next, when a symmetrical waveform is used as the periodic voltage signal, specifically, when using Fig. 9 The rise time τ of the signal shown r The fall time τ of the signal f When an equal trapezoidal wave is used as a periodic voltage signal, if the periodic voltage signal is expanded in Fourier series, it is expressed by the following formula (N).

[0143] [Formula 12]

[0144]

[0145] In formula (N), if f = 1 / T, τ = T / 2, then when n is an even number, sin(nπf0τ) = 0. Therefore, when a symmetrical waveform is used as a periodic voltage signal, the higher harmonic components of even multiples of the frequency f0 can be deleted as shown in the following formula (O). Fig. 9 When the ideal trapezoidal waveform shown in the figure is slightly deformed, some harmonic components of even-numbered multiples of frequency f0 will remain. However, as long as the signal waveform can be roughly approximated to the ideal trapezoidal waveform, the harmonic components of even-numbered multiples of frequency f0 will be small enough to be ignored.

[0146] Therefore, as shown in the following equation (O), the harmonic components of even-numbered multiples of the frequency f0 can be deleted from equation (M).

[0147] [Formula 13]

[0148]

[0149] By transforming the formula (0), we can obtain the formula (3) and (3)'. Therefore, the formula (3) and (3)' are nothing more than the formula obtained by expanding the periodic voltage signal by Fourier series.

[0150] Next, when a rectangular wave is used as the periodic voltage signal, since the rectangular wave is a symmetrical waveform, equations (3) and (3)' can be applied.

[0151] Furthermore, regarding the peak value B of the nth harmonic n We know that if it is an ideal rectangular wave, then when the peak value of the rectangular wave is set to B, the peak value B n =(4 / π)·(B / 2)·{1 / (2n-1)}. Therefore, by using the power A of equations (3) and (3)' (mn)m Substitute this term into the peak value B of the nth harmonic (mn)m By transforming the equation, we can obtain equation (1) and equation (1)'. Therefore, equation (1) and equation (1)' are nothing more than equations obtained by expanding the periodic voltage signal by Fourier series.

[0152] That is, a circuit characteristic measurement system of an example of the present invention includes: a signal voltage generating circuit, which sequentially applies a plurality of periodic voltage signals to a circuit under test of a measurement object, wherein the plurality of periodic voltage signals respectively have a specified reference frequency and a frequency that is an integer multiple of the reference frequency; a measurement circuit, which sequentially measures the power of a signal generated in the circuit under test due to sequentially applying the periodic voltage signals to the circuit under test; and a transfer function calculation unit, which uses a predetermined formula to calculate the transfer function of the circuit under test based on the power measured by the measurement circuit, wherein the periodic voltage signal includes a high-order frequency component.

[0153] In addition, a circuit characteristic measuring method of an example of the present invention includes: a signal voltage application step, in which a plurality of periodic voltage signals are sequentially applied to a circuit under test of a measuring object, wherein the plurality of periodic voltage signals respectively have a specified reference frequency and a frequency that is an integer multiple of the reference frequency; a measuring step, in which the power of a signal generated in the circuit under test due to application of the periodic voltage signal to the circuit under test is respectively measured; and a transfer function calculation step, in which a transfer function of the circuit under test is calculated based on a plurality of powers measured by the measuring circuit using a predetermined formula, wherein the periodic voltage signal includes a high-order frequency component.

[0154] According to these structures, a plurality of periodic voltage signals are sequentially applied to the circuit under test of the measurement object, and the power generated thereby is sequentially measured, and the transfer function of the circuit under test is calculated based on the power using a preset formula. In this case, it is not necessary to use a current source circuit that performs current control to flow a rectangular wave current as in Non-Patent Document 1, and the transfer function of the circuit under test can be calculated, that is, the characteristics of the circuit under test can be measured by generating a voltage signal that is easy to generate, that is, a periodic voltage signal.

[0155] In addition, it is preferable that the periodic voltage signal is a rectangular wave, and when the reference frequency is set to f0, the frequencies of the plurality of periodic voltage signals are odd-numbered multiples of the reference frequency f0.

[0156] According to the above configuration, a rectangular wave periodic voltage signal which is easy to generate is used, and there is no need to generate a periodic voltage signal with a frequency which is a multiple of the reference frequency f0, so that the characteristics of the circuit to be measured can be easily measured.

[0157] In addition, it is preferable that when the frequency of the periodic voltage signal is set to f0, 3f0, 5f0, ... and the power of the periodic voltage signal is set to A, the transfer function calculation unit calculates the transfer function H of the circuit under test by performing the operation represented by the following equation (1): 2 (f0),H 2 (3f0),H 2 (5f0),···.

[0158] [Formula 1]

[0159]

[0160] According to the above configuration, when a rectangular wave is used as the periodic voltage signal, the transfer function H of the circuit under test can be easily calculated by performing the operation shown in equation (1). 2 (f0),H 2 (3f0),H 2 (5f0),···that is, the circuit characteristics.

[0161] In addition, it is preferred that the frequency serving as the reference frequency is set to mf0 (m=1), the integral multiple frequency is set to mf0 (m is an integer greater than 2), and further include pre-storing the power A of the fundamental wave and its higher harmonics (mn)m (n is the order of the higher harmonic: n=1, 2, 3, ...), the transfer function calculation unit calculates the power A stored in the storage unit according to the power A stored in the storage unit. (mn)m The transfer function H of the circuit under test is calculated by performing the operation shown in the following equation (2). 2 (mf0)(m=1, 2, 3, ···), the power A stored in the storage unit (mn)m (n=1, 2, 3, ···) is the power contained in each of the periodic voltage signals measured by the measuring circuit when the periodic voltage signal of the frequency mf0 (m=1, 2, 3, ···) is applied from the signal voltage generating circuit to the measuring circuit without passing through the measured circuit.

[0162] [Formula 2]

[0163]

[0164] According to the above configuration, regardless of the waveform of the periodic voltage signal, it is easy to calculate the transfer function H of the circuit under test by the operation shown in equation (2).2 (mf0)(m=1, 2, 3, ···) is the circuit characteristic.

[0165] In addition, it is preferred that the periodic voltage signal can be set to the following waveform, that is, a symmetry axis perpendicular to the time axis is configured at a point on the time axis in the signal waveform of one cycle, thereby symmetrically relative to the symmetry axis, the frequency as the reference frequency is set to mf0 (m=1), the integral multiple frequency is set to mf0 (m is an odd number greater than 3), and further includes pre-storing the power A of the fundamental wave and its higher harmonics (mn)m (n is the order of the higher harmonics: n=1, 3, 5, ...), and the transfer function calculation unit calculates the power A stored in the storage unit. (mn)m The transfer function H of the circuit under test is calculated by performing the operation shown in the following equation (3). 2 (mf0)(m=1, 3, 5, ···), the power A stored in the storage unit (mn)m (n=1, 3, 5, ···) is the power contained in each of the periodic voltage signals measured by the measuring circuit when the periodic voltage signal of the frequency mf0 (m=1, 3, 5, ···) is applied from the signal voltage generating circuit to the measuring circuit without passing through the measured circuit.

[0166] [Formula 3]

[0167]

[0168] According to the above configuration, when a waveform that can be set to the following waveform is used as a periodic voltage signal, the transfer function H of the circuit under test can be easily calculated by performing the operation shown in equation (3). 2 (mf0) (m=1, 3, 5, .. .) is a circuit characteristic. In the waveform, a symmetry axis perpendicular to the time axis is configured at a point on the time axis in one cycle of the signal waveform, thereby being symmetrical relative to the symmetry axis.

[0169] Furthermore, it is preferable that the measuring circuit measures the power of reflected waves formed when the periodic voltage signal is reflected in the measured circuit.

[0170] According to the above structure, the transfer function, i.e., the circuit characteristics of the circuit under test can be easily calculated by measuring the power of reflected waves formed by the periodic voltage signal reflecting in the circuit under test, instead of the transmitted waves formed by the periodic voltage signal passing through the circuit under test.

[0171] In the circuit characteristic measuring system and circuit characteristic measuring method having such a configuration, the characteristics of the circuit to be measured can be measured without using a current source circuit that performs current control to flow a rectangular wave current.

[0172] Furthermore, the specific embodiments or examples given in the section "Specific embodiments" are only intended to clarify the technical content of the present invention, and the present invention should not be interpreted narrowly by being limited to such specific examples.

Claims

1. A circuit characteristic measurement system, comprising: A signal voltage generating circuit sequentially applies a plurality of periodic voltage signals to a circuit under test of a measurement object, wherein the plurality of periodic voltage signals respectively have a predetermined reference frequency and a frequency that is an integer multiple of the reference frequency; a measuring circuit for sequentially measuring the power of a signal generated in the measured circuit due to sequentially applying the periodic voltage signal to the measured circuit; as well as a transfer function calculation unit that calculates a transfer function of the circuit under test based on the power measured by the measurement circuit using a preset formula, The periodic voltage signal contains a high-order frequency component and is a rectangular wave or a trapezoidal wave with equal rising and falling inclinations. When the reference frequency is set to f0, the frequencies of the plurality of periodic voltage signals are odd-numbered multiples of the reference frequency f0.

2. The circuit characteristic measurement system according to claim 1, wherein: When the frequency of the periodic voltage signal is set to f0, 3f0, 5f0, ..., the power of the signal generated in the circuit under test by sequentially applying the periodic voltage signal to the circuit under test is set to P(f0), P(3f0), P(5f0), ..., the power of the periodic voltage signal is set to A, and the peak voltage of the periodic voltage signal is set to B, the transfer function calculation unit calculates the transfer function H of the circuit under test by performing the operation represented by the following formula (1): 2 (f0),H 2 (3f0),H 2 (5f0), ···, [Formula 1] 3. The circuit characteristic measurement system according to claim 1, wherein: The periodic voltage signal can be set to a waveform such that a symmetry axis perpendicular to the time axis is arranged at a point on the time axis in a signal waveform of one cycle, thereby being symmetrical with respect to the symmetry axis. A frequency m times the odd number of the reference frequency f0 is set as mf0, and the power of the signal generated in the circuit under test is set as P(mf0) by sequentially applying the periodic voltage signal to the circuit under test. The method further comprises setting the order of the higher harmonic relative to the fundamental wave to an odd number n, and pre-storing the power A of the higher harmonic (mn)m The storage unit, The peak voltage of the high-order harmonic is set as B (mn)m , The transfer function calculation unit calculates the power A stored in the storage unit based on the power A stored in the storage unit. (mn)m The transfer function H of the circuit under test is calculated by performing the operation shown in the following equation (3). 2 (mf0), The power A stored in the storage unit (mn)m is the power contained in each of the periodic voltage signals measured by the measuring circuit when the periodic voltage signal of the frequency mf0 is applied from the signal voltage generating circuit to the measuring circuit without passing through the measured circuit, [Formula 3] 4. The circuit characteristic measurement system according to any one of claims 1 to 3, wherein: The measuring circuit measures the power of reflected waves formed by the periodic voltage signal being reflected in the measured circuit.

5. A method for measuring circuit characteristics, comprising: a signal voltage applying step of sequentially applying a plurality of periodic voltage signals to the circuit under test of the test object, wherein the plurality of periodic voltage signals respectively have a predetermined reference frequency and a frequency that is an integer multiple of the reference frequency; a measuring step of measuring power of a signal generated in the circuit under test due to application of the periodic voltage signal to the circuit under test; as well as a transfer function calculation step of calculating a transfer function of the circuit under test based on the power measured in the measurement step using a predetermined formula, The periodic voltage signal contains a high-order frequency component and is a rectangular wave or a trapezoidal wave with equal rising and falling inclinations. When the reference frequency is set to f0, the frequencies of the plurality of periodic voltage signals are odd-numbered multiples of the reference frequency f0.

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