JP3270348B2 - Noise analysis device for self-excited system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise analyzer for analyzing noise of a self-excited system including electronic circuits such as an oscillator and a multivibrator.

[0002]

2. Description of the Related Art As a method of analyzing noise of an electronic circuit, there is a method of adding a noise source to a linear equivalent circuit at a DC operating point, calculating a transfer function from the noise source to an output, and calculating output noise. . However, a system such as an oscillator whose operating point changes over time cannot be analyzed by the above method.

On the other hand, a noise analysis method for a circuit whose operating point periodically changes due to periodic excitation, such as a mixer circuit or a switched capacitor circuit, is described below.
It is proposed in the following documents [1] and [2].

Document [1]: Muniko Okumura, Hiroshi Tanimoto, Tsutomu Sugawara, "A Computer-Based Noise Analysis of a Nonlinear Circuit with Two Input Signals", IEICE Transactions A, Vol. J7
3-ANo. 8, pp. 1342-1349,199
0. Reference [2]: Makiko Okumura, Hiroshi Tanimoto, Tetsuro
Itakura and TsutomuSugawara, “Numerical noise an
alysis for nonlinear cicuits with aperiodic large
signal excitation including cyclostationary noise
sources, ”IEEE Trans.Circuits Syst., I: Fundamental
Theory and Applications, Vol. 40, No. 9, pp. 581-590, Se
pt. 1993. Further, the following document [3] discloses a device for calculating the noise of an oscillator. Reference [3]: Andy Howard, “Simulate oscillator phas
e noise, ”Maicowaves & RF, pp.64-70, November 1993.

[0005]

However, neither of the above-mentioned documents [1] and [2] describes an analysis method for a self-excited system in which the operating point changes periodically. Therefore, conventionally, there is no method of simulating the noise of a general self-excited system before trial production, and at the design stage, a rough estimate can be made from past experience.

[0006] Further, in the document [3], only the noise of an oscillator including a resonator can be calculated, and the output power cannot be calculated and output by separating it into amplitude noise and phase noise. The present invention has been made in view of such problems, and an object of the present invention is to analyze noise of a self-excited system in advance by simulation without actually prototyping the system. It is to provide a device.

It is another object of the present invention to provide a noise analysis apparatus which separates output power into phase noise and amplitude noise, calculates and outputs the output power, and improves the output accuracy of each noise.

[0008]

In order to achieve the above object, a noise analysis apparatus for a self-excited system according to a first aspect of the present invention inputs a configuration of a self-excited system, parameter values, analysis conditions, and the like. A noise source is added to the input means, the periodic stationary solution calculation means for calculating the periodic stationary solution of the self-excited system, and the periodic linear time-varying system obtained by linearizing the self-excited system around the periodic stationary solution. Noise source adding means, and a time-varying transfer function calculating means for calculating a time-varying transfer function of the periodic linear time-varying system to which the noise source is added for each noise source,
It comprises a folded component computing means for adding the power of the time-varying transfer function folded back to the frequency to be observed, and an output means for selectively outputting the computation result of each computing means as an analysis result relating to noise.

A noise analysis device for a self-excited system according to a second invention is the noise analysis device for a self-excited system according to the first invention, wherein the output means is operated by the periodic stationary solution operation means. And a display means for combining and displaying the periodic stationary solution and the noise obtained by the calculation by the time-varying transfer function calculation means and the aliasing component calculation means.

A noise analysis device for a self-excited system according to a third aspect of the present invention includes an input means for inputting a configuration of the self-excited system, parameter values, analysis conditions, and the like, and a periodic stationary solution of the self-excited system. A noise source addition means for adding a noise source to a periodic linear time-varying system obtained by linearizing a self-excited system around a periodic steady solution, and a noise source. Time-varying transfer function computing means for computing a time-varying transfer function of a periodic linear time-varying system for each noise source, and a phase for computing phase noise and amplitude noise of the time-varying transfer function obtained by this computation. The apparatus includes an amplitude noise calculating means, and an output means for selectively outputting a calculation result of each of the calculating means as an analysis result regarding noise.

A noise analysis apparatus for a self-excited system according to a fourth aspect of the present invention includes an input means for inputting a configuration of the self-excited system, parameter values, analysis conditions, and the like, and a periodic stationary solution of the self-excited system. Attention should be paid to the noise source addition means for adding a noise source to the periodic linear time-varying system obtained by linearizing the self-excited system around the periodic steady solution, A first noise component output after frequency conversion to a frequency of interest and a second noise component output without frequency conversion to obtain a periodic linear time-varying system to which a noise source is added. A time-varying transfer function calculating means for calculating a time-varying transfer function for each noise source; and a power of a portion of the time-variant transfer function relating to the first and second noise components, which contributes to phase noise, for each noise source. Phase noise calculating means for adding And an output means for outputting the analysis results regarding selective noise calculation result of the respective arithmetic means.

A noise analysis apparatus for a self-excited system according to a fifth aspect of the present invention includes an input means for inputting a configuration of the self-excited system, parameter values, analysis conditions, and the like, and a periodic stationary solution of the self-excited system. Attention should be paid to the noise source addition means for adding a noise source to the periodic linear time-varying system obtained by linearizing the self-excited system around the periodic steady solution, A first noise component output after frequency conversion to a frequency of interest and a second noise component output without frequency conversion to obtain a periodic linear time-varying system to which a noise source is added. A time-varying transfer function calculating means for calculating a time-varying transfer function for each noise source; and a power of a portion of the time-variant transfer function relating to the first and second noise components, which contributes to amplitude noise, for each noise source. Amplitude noise calculating means for adding And an output means for outputting the analysis results regarding selective noise calculation result of the respective arithmetic means.

A noise analysis device for a self-excited system according to a sixth invention is the noise analysis device for a self-excited system according to the third invention, wherein the time-variant transfer function obtained by the phase-amplitude noise calculation means is obtained. The apparatus further includes a normalizing means for normalizing the phase noise and the amplitude noise using the periodic stationary solution from the periodic stationary solution calculating means.

A noise analysis apparatus for a self-excited system according to a seventh invention is the noise analysis apparatus for a self-excited system according to the fourth invention, wherein the phase of the time-varying transfer function obtained by the phase noise calculation means is obtained. The image processing apparatus further includes a normalizing unit that normalizes the noise using the periodic stationary solution from the periodic stationary solution calculating unit.

The noise analyzing apparatus for a self-excited system according to an eighth aspect of the present invention is the noise analyzing apparatus for a self-excited system according to the fifth aspect, wherein the amplitude of the time-varying transfer function obtained by the amplitude noise calculating means is obtained. The image processing apparatus further includes a normalizing unit that normalizes the noise using the periodic stationary solution from the periodic stationary solution calculating unit.

In a ninth aspect of the present invention, there is provided a noise analysis apparatus for a self-excited system according to any one of the third to eighth aspects. To provide the output for the detuning frequency.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a noise analysis device for a self-excited system according to a first embodiment of the present invention. Here, the self-excited system refers to a system in which self-excited vibration occurs as a steady state without applying a periodic external force. This self-excited oscillation has a constant amplitude and frequency, and may be called an autonomous system.

As shown in FIG. 1, a noise analysis device according to the present embodiment comprises an input unit 1 and a periodic stationary solution operation unit 2.
Noise source adding means 3, time-varying transfer function calculating means 4,
It comprises a folded component calculation means 5 and an output means 6.

The input means 1 is an input means for designating the configuration and parameter values of the self-excited system, an analysis condition such as a frequency to be observed, a band of a noise source, and an output method.
As a method of specifying the output frequency, for example, a method of specifying how much the output frequency is increased or decreased with reference to the oscillation frequency is possible.

The periodic steady solution calculating means 2 is a means for calculating a periodic steady solution such as the oscillation frequency and the oscillation amplitude of the self-excited system. As a calculation method, there is a method of numerically integrating a differential equation, and a method disclosed in the following document [4].

Reference [4]: KSKundert, JKWhite, and
A. Sangiovanni-Vincentelli, Steady-State Methods for
Simulating Analog and Microwave Circuits, Kluwer A
cademic Publishers, USA, 1990. Here, if the self-excited system is represented by the following equation (1), and the stationary solution is represented by v _ss , the stationary solution is periodic.

[0022]

(Equation 1)

The noise source adding means 3 is a means for adding a noise source to the periodic linear time-varying system. Since the noise is usually a small signal compared to the amplitude of the self-excited system, the relationship between the noise and its output can be considered to be linear. Therefore, the analysis can be performed using a linear equivalent circuit linearized around the periodic stationary solution of the self-excited system.

A linear equivalent circuit obtained by linearizing the self-excited system around the periodic stationary solution calculated by the periodic stationary solution calculating means 2 becomes a periodic linear time-varying system in which parameters periodically change. Then, the following equation (3) is obtained.

[0025]

(Equation 2) Here, assuming that a vector indicating the position of the k-th noise source is z _k , the following equation (4) is obtained by adding this noise source to the periodic linear time-varying system.

[0026]

(Equation 3)

FIG. 2 is a circuit diagram when a noise source representing the thermal noise of the resistor is added to the resistor. In the drawing, reference numeral 7 denotes a case where the current source is added, and reference numeral 8 denotes a case where the current source is added. Next, the time-varying transfer function calculating means 4 shown in FIG. 1 is a means for calculating a transfer function from a noise source to an output of a periodic linear time-varying system to which a noise source is added. Techniques for calculating such a transfer function are described in, for example, the following references [5], [6], and [7].

Reference [5]: Makiko Okumura, Tsutomu Suga
wara and Hiroshi Tanimoto, "An Efficient Small Sign
al Analysis Method of Nonlinear Circuits withTwo F
requency Excitations, ”IEEE Trans.Comput.-Aided D
es.IntegratedCircuits Syst., Vol.9, No.3, pp.225-235,
Mar, 1990. Reference [6]: Makiko Okumura, Hiroshi Tanimoto, Tetsuro
Itakura and TsutomuSugawara, “Numerical noise ana
lysis for nonlinear circuits with aperiodic large
signal excitation including cyclostationary noises
ources, ”IEEE Trans.Circuits Syst., I: Fundamental
Theory and Applications, Vol. 40, No. 9, pp. 581-590, Sep
t.1993. Reference [7]: Stephen A. Mass, Nonlinear Microwave Circ
uits, Artech HouseBoston, London, 1988. These methods use the time-varying parameters of a periodically changing circuit to calculate the transfer function that appears as an output at the same frequency as the input frequency, and the transfer function of other harmonic components. Calculate.

FIG. 3 shows the spectrum of the time-varying transfer function appearing at the output when the input frequency is ω. Where ω
₀ = 2πf ₀ . FIG. 4 shows a spectrum of a transfer function that overlaps with the frequency ω. As shown in the figure, assuming that the noise source has a certain band, the output noise components of the frequency ω include:, H ₁ (ω−ω ₀ ), H ₀ (ω), H
_-1 (ω + ω ₀ ), H _-2 (ω + 2ω ₀ ),... The time-varying transfer function calculating means 4 calculates these transfer functions for each noise source. The user specifies how much the harmonic component of the time-varying transfer function is to be calculated by the calculating means 4 or how the band of the noise source is to be obtained. Alternatively, a predetermined value is used.

Next, the aliasing component calculating means 5 calculates the power of the time-varying transfer function, which is calculated by the time-varying transfer function calculating means 4 for each noise source, at the frequency to be observed, by the following equation. It is a means for adding using.

[0031]

(Equation 4)

Here, S (ω) is the power spectrum density of the noise output, H _l (ω−1ω ₀ ) is the transfer function, and s (ω−
lω ₀ ) is the power spectrum of the noise source, ω is the frequency of interest, ω ₀ = 2πf ₀ is the oscillation frequency, and L is a constant arbitrarily set by the user.

Next, the output means 6 outputs, for each order, the noise for each noise source obtained by summing the noise for each noise source and the total noise for all the noise sources, and the total noise of all the noise sources. And display means for displaying the analysis result, as described below. Noise near the oscillation frequency is an important item included in the design specifications.

FIG. 5 is a diagram showing a configuration of an oscillator (Wien Bridge Oscillator) as an example circuit of the self-excited system.
FIG. 6 shows an example in which a noise source is added to the transistor 9 included in the oscillator. Here, as noise sources of the transistor 9, thermal noise 10 of the base resistance and thermal noise 1 of the emitter resistance
1, thermal noise 12 of the collector resistance, shot noise 13 of the base current IB, and shot noise 14 of the collector current IC.

FIG. 7 shows an example in which a noise source is added to a diode included in an oscillator. Here the diode 15
The thermal noise 16 of the resistor Rd and the shot noise 17 of the current Id were considered as noise sources.

FIGS. 8 to 10 show the results of analyzing the oscillator having such a configuration according to the present embodiment. FIG. 8 shows a periodic stationary solution calculated by the periodic stationary solution calculating means 2. The oscillation frequency was 146.8 [kHz]. FIG. 9 is a diagram showing the total output noise calculated in the present embodiment. Here, the folded components are considered up to the eighth order.

FIG. 10 shows an output result in which a noise source having a large noise is displayed. In this example circuit, it can be seen that the effects of the shot noise of the base current of the transistor Q1 and the thermal noise of the resistor R1 shown in FIG. 5 are large.

FIG. 11 shows the spectrum of the fundamental wave (oscillation frequency) of the periodic stationary solution calculated by the periodic stationary solution calculating unit 2, the time-varying transfer function calculating unit 4, and the aliasing component calculating unit 5.
And the noise power spectral density calculated in the above. Evaluation of how much the noise level is suppressed with respect to the spectrum of the fundamental wave within the determined frequency band is an essential item for system design.
Therefore, it is very useful to analyze the result as shown in FIG.

According to the first embodiment, the noise of the self-excited system can be analyzed in advance by simulation without actually producing a prototype system.
Furthermore, when measuring a prototype system as before, only the total noise from all noise sources can be measured,
In the simulation according to the present embodiment, since noise for each noise source and noise for each order of the transfer function can be separately analyzed and separately output, design is performed again in consideration of the analysis result. Feedback to the design can be achieved.

Hereinafter, as a second embodiment of the present invention, an embodiment in which the output power is separated into phase noise and amplitude noise to calculate and output will be described. FIG. 12 is a block diagram showing a configuration of a noise analysis device for a self-excited system according to the second embodiment of the present invention. As shown in the figure, the noise analysis apparatus includes an input unit 11, a periodic stationary solution operation unit 12, a noise source addition unit 13, a time-varying transfer function operation unit 14, a phase noise operation unit 15, an amplitude noise Calculation means 16 and normalization means 1
7 and output means 18.

The input means 11 includes information about the system such as the configuration and element values of the self-excited system, values of model parameters, initial values of oscillation frequencies, analysis conditions such as output frequencies and noise source bands, and types of noise ( This is a means for designating a phase noise, an amplitude noise, a total thereof, and the like, and a method of outputting a noise source to be output.

The band of the noise source is specified by the frequency. Alternatively, it is specified by an integer related to the order of the transfer function. Here, the order is a periodic time-varying transfer function H (j
ω, t) is the value of 1 when Fourier series expansion is performed for time t as follows.

[0043]

(Equation 5)

Here, ω ₀ is the oscillation frequency. As for the method of specifying the output frequency, a detuning frequency from the oscillation frequency can be specified in addition to the absolute value of the frequency. At the input stage before performing the steady-state analysis, the exact oscillation frequency is not yet known, but a detuning frequency can be designated for the oscillation frequency as a result of the steady-state analysis. The detuning frequency is a value indicating how far the frequency is from the oscillation frequency. Here, for the detuning frequency, the number of points on a logarithmic scale, the number of points on a linear scale, or the number of points per octave, or 1
You can specify the number of points per decade.

The periodic steady solution calculation means 12 is means for calculating self-excited vibration when the self-excited system reaches a steady state. For example, as described in the first embodiment, the calculation can be performed using the shooting method in the time domain or the harmonic balance method in the frequency domain shown in the document [4]. The periodic steady solution may be calculated by performing a transient analysis (numerical integration) until the oscillation reaches a steady state. When obtaining a steady-state solution of an oscillator using the shooting method or the harmonic balance method, if an initial value of the oscillation frequency is given without knowing the exact oscillation frequency in advance, a steady-state solution including the oscillation frequency is finally calculated. Can be.

The noise source adding means 13 is a means for adding a noise source to the self-excited system. FIG. 2 shown in the first embodiment
For example, in the case of thermal noise of a resistor, a current source is connected in parallel with the resistor. The current value of the current source is determined by the power spectrum density of the noise source.

The time-varying transfer function calculating means 14 is a means for calculating a transfer function from a noise source to an output. Since the noise is insignificant and the relationship between the noise and the output is considered linear, the self-excited system can be viewed as a periodic time-varying circuit linearized around a periodic stationary solution to the noise. The function calculating means 14 is means for calculating a transfer function from the noise source to the output of the periodic time-varying circuit. Here, the transfer function is an output when the input amplitude is 1, and when the input amplitude is α, the output becomes α times the transfer function. When the amplitude of the current source added to the noise source as input is b, there are a method of multiplying the transfer function by b and a method of calculating the output with respect to the input of the amplitude b. In this time-varying transfer function calculating means 14,
As in the latter case, a value b times the transfer function may be obtained from the beginning.

In the following, in the case of a periodic time-varying transfer function or a transfer function, the Fourier component H on the right side of the equation (1) '
_l (jω), l =..., -1, 0, 1, 2,. The time-varying transfer function calculating means 14 uses a time domain method (references [4] and [5] described in the first embodiment) and a frequency domain method using a harmonic balance method (reference [7]). To calculate the transfer function.

More specifically, the time-varying transfer function calculating means 14
Is a means for calculating a transfer function (output) of each component overlapping with a certain output frequency, a first calculating means 19 for calculating a component output at the same frequency as the frequency of noise, and another frequency And a second calculating means 20 for calculating a component whose frequency has been converted to an output frequency of interest.

FIG. 13 shows the transfer function of the component output to the output frequency ω without frequency conversion. FIG. 14 shows the frequency conversion when the frequency component of the noise is ω _i . It shows the transfer function output at ω _i + ω ₀ (= ω). In the first embodiment, since it is not necessary to distinguish between the two, the first calculation unit 19 and the second calculation unit 20 are one unit.

The amplitude noise calculating means 15 is means for calculating the power which contributes to the amplitude noise indicating how much the oscillation amplitude changes due to the addition of the noise. The phase noise calculating means 16 is the means for calculating the phase noise. This means calculates the power contributing to the phase noise indicating how much the oscillation frequency changes. Here, the noise that is not frequency-converted by the first calculating means 19 is originally a random signal, and the phase of the random signal itself has no meaning, so the power contributing to the phase / amplitude noise is 1 / Two each. Of the frequency-converted components calculated by the second calculation means 20, the power of the amplitude-modulated component is amplitude noise, and the power of the frequency-modulated component is phase noise. The amplitude-modulated component is
The real part of the frequency-converted component and the frequency-modulated component are determined by the imaginary part of the frequency-converted component.

The reason is as follows.
Now, consider a time-varying transfer function H ₁ (ω _i ) where the input frequency is ω _i and the output frequency is ω _i + ω ₀ . It is as follows when written separately for amplitude and phase.

[0053]

(Equation 6)

From the viewpoint of the carrier signal moving at the oscillation frequency ω ₀ , the phase of the output signal rotating at the frequency ω _i , that is, the phase of the signal rotating at ω _i + ω ₀ , is determined based on the carrier. It indicates whether or not Assuming that the output of the angular frequency ω ₀ + ω _i of the noise as viewed from the carrier signal operating at the oscillation frequency ω ₀ is x _i (t) ′,

[0055]

(Equation 7)

The first and second terms of the equation (5) 'are the Fourier transform of the real part of the time-varying transfer function, and the third and fourth terms are the Fourier transform of the imaginary part. 16 and 17 show vector diagrams of the real part and the imaginary part of the time-varying transfer function H ₁ (ω _i ), respectively.

Similarly, the output of the angular frequency −ω _i of the noise viewed from the carrier operating at the oscillation frequency ω ₀ is x ′
When _{-i (t), x '-i} (t) = H 1 (-ω i) cos (-ω i t) + jH 1 (-ω i) sin (-ω i t) (6)' (6 ) 'Is Fourier transformed,

[0058]

(Equation 8)

[0059] Here, H ₁ (omega _i) and H ₁ (- [omega] _i) from a relationship of complex conjugate to each other, in consideration of this (7) 'in FIG. 18 and 19 of Formula H ₁ (- The real and imaginary parts of ω _i ) are represented by vectors.

Since H ₁ (ω _i ) and H ₁ (−ω _i ) are correlated with each other, their real parts, FIG. 16 and FIG.
Is drawn on the same complex plane as a vector, and FIG. 20 is drawn when the respective imaginary parts of FIG. 17 and FIG. 19 are drawn on the same complex plane as a vector. From this figure, it can be seen that the real part of the frequency-converted component is in phase with the carrier and represents the amplitude modulation component, and the imaginary part is orthogonal to the carrier and represents the frequency modulation component. As a result, the real part and the imaginary part of the time-varying transfer function (output) indicate the phase noise and the amplitude noise of the frequency-converted noise output, respectively.

Therefore, in the amplitude noise calculating means 15 for calculating the power contributing to the amplitude noise, the first calculating means 19
1/2 of the power of the frequency-unconverted component calculated in
The power of the real part of the frequency-converted component calculated by the second calculating means 10 is added according to the following equation (8) '. The phase noise calculating means 16 for calculating the power contributing to the phase noise is １ ／ of the power of the frequency-unconverted component calculated by the first calculating means 19 and the frequency conversion calculated by the second calculating means 20. The power of the imaginary part of the component is added according to the following equation (9) '.

[0062]

(Equation 9)

Here, Im in the equation (8) 'represents an imaginary part, and Re in the equation (9)' represents a real part. Next, the normalizing means 17 is means for calculating the normalized amplitude noise and the normalized phase noise defined as follows.

[0064]

(Equation 10)

Here, N _amp and N _phs indicate normalized amplitude noise and normalized phase noise, respectively. According to the above definition, the normalizing means 17 includes the periodic stationary solution calculating means 12
Is provided with a power calculating means 21 for calculating the spectrum of the oscillation frequency and its power using the result calculated in step (1). The result calculated by the amplitude noise calculating means 15 and the phase noise calculating means 16 is calculated by the power calculating means 21. Divided by the result
_Calculate N _amp and N _phs .

When the unit is expressed in dBc / Hz, in the above case, 10 log {N _amp }, 10 log {N _phs }
Becomes Usually, the result measured by the phase noise measuring instrument is the above-described normalized phase noise, which is often referred to simply as phase noise.

The method of calculating the spectrum by the power calculating means 21 includes, for example, fast Fourier transform (FFT), discrete Fourier transform (DFT), and Fourier numerical integration.
When the periodic stationary solution is obtained by a frequency domain method such as the harmonic balance method, the spectrum of the oscillation frequency has already been calculated by the periodic stationary solution calculating means 12, so that
Use the result directly.

The output means 18 is a means for outputting a calculation result in the format specified by the input means 11. Phase noise or amplitude noise for each noise source, or their sum,
This is a means for outputting the total phase noise or the amplitude noise of all the noise sources or the total thereof. Further, the output of each order of the transfer function is also possible, and the phase noise and the amplitude noise of the component whose frequency is converted from the baseband component to the vicinity of the oscillation frequency, or the total thereof can be output. The output for each order of the transfer function can be further output for each noise source.

Conventionally, there was no device for separating and outputting amplitude noise and phase noise. However, it is necessary to know whether the output noise of a certain noise source contributes to the phase or the amplitude. Important for designers. FIG. 15 is a diagram that outputs the phase noise, the amplitude noise, and the total thereof.
The horizontal axis shows the detuning frequency from the oscillation frequency. Of interest to designers are frequencies near the oscillation frequency. To do so, from the logarithmic representation of the absolute value of the frequency,
The logarithmic representation of the detuning frequency has the advantage that a sufficient frequency point near the oscillation frequency can be taken. In the output means 18, based on the items designated by the input means 11,
The result is output with respect to the detuning frequency based on the oscillation frequency of the result calculated by the periodic stationary solution calculation means 12.

According to the second embodiment described above, it is possible to analyze the noise of the self-excited system by simulation in advance without actually producing a system. In addition, since the amplitude noise and the phase noise are calculated and output separately, the output accuracy of each noise is improved.

When measuring the prototype system, only the total noise from all noise sources can be measured.
In the simulation, the noise for each noise source, the noise for each order of the transfer function, the amplitude noise, and the phase noise can be separated and analyzed and output separately. And the feedback to the design can be achieved.

[0072]

According to the present invention, the noise of the self-excited system can be analyzed in advance by simulation without actually producing a prototype system. Also,
Since the output power is calculated and output by separating the output power into phase noise and amplitude noise, the output accuracy of each noise can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a noise analysis device of a self-excited system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a thermal noise source of a resistor.

FIG. 3 is a diagram illustrating a spectrum of a time-varying transfer function appearing in an output when an input frequency is ω.

FIG. 4 is a diagram illustrating a spectrum of a transfer function that overlaps with a frequency ω.

FIG. 5 is a diagram showing a configuration of an oscillation circuit as an example circuit of the self-excited system.

FIG. 6 is a diagram illustrating a configuration in which a noise source is added to a transistor included in an oscillation circuit.

FIG. 7 is a diagram showing a configuration in which a noise source is added to a diode included in an oscillation circuit.

FIG. 8 is a diagram showing a periodic stationary solution of the example circuit.

FIG. 9 is a diagram showing total output noise calculated in the present embodiment.

FIG. 10 is a diagram illustrating an output result in which a noise source having a large noise is displayed.

FIG. 11 is a diagram in which the spectrum of the fundamental wave of the oscillator and the noise power spectrum density are superimposed and displayed.

FIG. 12 is a block diagram illustrating a configuration of a noise analysis device for a self-excited system according to a second embodiment of the present invention.

FIG. 13 is a diagram showing a transfer function that is not frequency-converted.

FIG. 14 is a diagram showing a transfer function subjected to frequency conversion.

FIG. 15 is a diagram showing a result of outputting a phase noise, an amplitude noise, and a total thereof.

FIG. 16 is a vector diagram of the real part of the time-varying transfer function H ₁ (ω _i ).

FIG. 17 is a vector diagram of an imaginary part of a time-varying transfer function H ₁ (ω _i ).

FIG. 18 is a vector diagram of a real part of the time-varying transfer function H ₁ (−ω _i ).

FIG. 19 is a vector diagram of an imaginary part of a time-varying transfer function H ₁ (−ω _i ).

FIG. 20: Time-varying transfer functions H ₁ (ω _i ) and H ₁ (−ω _i )
FIG. 4 is a vector diagram of a real part.

FIG. 21. Time-varying transfer functions H ₁ (ω _i ) and H ₁ (−ω _i )
3 is a vector diagram of an imaginary part of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input means, 2 ... Periodic stationary solution calculation means, 3 ... Noise source addition means, 4 ... Time-varying transfer function calculation means, 5 ... Return component calculation means, 6 ... Output means, 7 ... Noise source of current, 8 ... voltage noise source, 11 ... input means, 12 ... periodic stationary solution calculation means, 13 ... noise source addition means, 14 ... time-varying transfer function calculation means, 15 ... amplitude noise calculation means, 16 ... phase noise calculation means, 17 normalizing means, 18 output means, 19 first calculating means, 20 second calculating means, 21 power calculating means.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 27/28 G01R 29/26 G06F 17/50

Claims (9)

(57) [Claims] An input means for inputting a configuration of a self-excited system, parameter values, analysis conditions, and the like; a periodic steady-state solution calculating means for calculating a periodic steady-state solution of the self-excited system; Source addition means for adding a noise source to a periodic linear time-varying system obtained by linearizing around a static stationary solution, and the time-varying transfer function of the periodic linear time-varying system with the noise source added to each noise source Time-varying transfer function calculating means for calculating the power of the time-varying transfer function that is folded back to the frequency to be observed, and a folded component calculating means for adding the power of the time-varying transfer function to the observed frequency. A noise analysis device for a self-excited system, comprising: output means for outputting. 2. The output means synthesizes the periodic stationary solution calculated by the periodic stationary solution calculation means with noise obtained by the calculation by the time-varying transfer function calculation means and the aliasing component calculation means. 2. The noise analyzing apparatus for a self-excited system according to claim 1, further comprising a display unit for displaying the noise. 3. A configuration of a self-excited system, input means for inputting parameter values, analysis conditions, and the like; periodic stationary solution calculation means for calculating a periodic stationary solution of the self-excited system; Source addition means for adding a noise source to a periodic linear time-varying system obtained by linearizing around a static stationary solution, and the time-varying transfer function of the periodic linear time-varying system with the noise source added to each noise source Time-variant transfer function calculating means for calculating each time, phase noise of the time-variable transfer function obtained by this calculation,
Noise analysis of a self-excited system, comprising: phase amplitude noise calculation means for calculating respective amplitude noises; and output means for selectively outputting the calculation results of the calculation means as analysis results relating to noise. apparatus. 4. A configuration of a self-excited system, input means for inputting parameter values, analysis conditions, and the like; periodic stationary solution calculation means for calculating a periodic stationary solution of the self-excited system; Source adding means for adding a noise source to a periodic linear time-varying system obtained by linearizing around a steady-state solution, and a first noise which is converted from another frequency to a frequency of interest and output. And a second noise component output without being frequency-converted to calculate a time-varying transfer function of a periodic linear time-varying system to which a noise source is added for each noise source. Function calculating means, phase noise calculating means for adding the power of a portion of the time-varying transfer function relating to the first and second noise components that contributes to phase noise for each noise source, and calculation results by the calculating means Selectively Noise Analysis device of a self-excited system, characterized by comprising output means for outputting the analysis result that, a. 5. An input means for inputting a configuration of a self-excited system, parameter values, analysis conditions, and the like; a periodic steady-state solution calculating means for calculating a periodic steady-state solution of the self-excited system; Source adding means for adding a noise source to a periodic linear time-varying system obtained by linearizing around a steady-state solution, and a first noise which is converted from another frequency to a frequency of interest and output. And a second noise component output without being frequency-converted to calculate a time-varying transfer function of a periodic linear time-varying system to which a noise source is added for each noise source. Function calculating means, amplitude noise calculating means for adding the power of a portion of the time-variant transfer function relating to the first and second noise components that contributes to the amplitude noise for each noise source, and calculation results by the calculating means Selectively Noise Analysis device of a self-excited system, characterized by comprising output means for outputting the analysis result that, a. 6. A normalizing means for normalizing phase noise and amplitude noise of a time-varying transfer function obtained by said phase amplitude noise calculating means using a periodic stationary solution from said periodic stationary solution calculating means. The noise analysis device according to claim 3, further comprising: 7. A normalizing means for normalizing phase noise of a time-varying transfer function obtained by said phase noise calculating means using a periodic stationary solution from said periodic stationary solution calculating means. The noise analysis device according to claim 4, wherein: 8. A normalizing means for normalizing the amplitude noise of the time-varying transfer function obtained by said amplitude noise calculating means using a periodic stationary solution from said periodic stationary solution calculating means. The noise analysis device according to claim 5, wherein: 9. The noise analysis apparatus for a self-excited system according to claim 3, wherein said output means provides an output with respect to a detuning frequency from an oscillation frequency.