JP5377400B2 - Noise injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise injector which can easily inject a noise signal of an arbitrary frequency to a target component. <P>SOLUTION: The noise injector comprises: a matching circuit 13 for matching impedance between a noise injection connector 11 and a variable capacitance member 14; and the variable capacitance member 14 one end of which is connected to an output side of the matching circuit 13 and the capacitance of which can be adjusted according to the frequency of a noise signal generated from a noise signal source 2, and switches the frequency band of the noise signal to be injected to a power terminal of the target component. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a noise injection device for injecting noise into a power supply terminal of a component to be injected with noise.

As shown in FIG. 6, the noise injection device disclosed in Patent Document 1 below is connected to a signal generator via a coaxial cable, and the noise generated from the signal generator is applied to the printed circuit board of the object to be measured. Injecting.
FIG. 7 is an explanatory diagram showing that the noise injection device achieves impedance matching between the signal generator side and the printed board side.

8 is a block diagram showing a noise injection device disclosed in the following Patent Document 1, and FIG. 9 is an equivalent circuit diagram of the noise injection device of FIG.
8 and 9, the SMA connector 101 is connected to a coaxial cable, and inputs noise generated from a signal generator and propagated through the coaxial cable.
The copper plate 102 forms a housing for mounting components such as the matching circuit 103.
The matching circuit 103 is a circuit that performs impedance matching between the signal generator side and the printed circuit board side.
The ground connection copper plate 104 is provided at the tip of the copper plate 102 and is connected to the ground of the printed circuit board.
The electric wire 105 is a line for electrically connecting the matching circuit 103 and the power supply pins of the printed board.

C1 and C2 are capacitors, R1 is a resistor, and L1 and L2 are inductors.
A signal portion on the signal generator side is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to one end of the capacitor C2 and the resistor R1.
The other end of the resistor R1 is connected to one end of the inductor L1 and the inductor L2, and the other end of the capacitor C2 and the inductor L2 is connected to the ground.

Next, the operation will be described.
Noise generated from the signal generator propagates on the coaxial cable and is input from the SMA connector 101.
Since one end of the electric wire 105 of the noise injection device is connected to the matching circuit 103 and the other end is connected to the power supply pin of the printed circuit board, impedance matching between the signal generator side and the printed circuit board side is achieved by the matching circuit 103. If so, noise input from the SMA connector 101 is injected into the printed circuit board via the electric wire 105.

At this time, the matching circuit 103 adjusts the constants of the circuit composed of the inductor and the capacitor through the measurement of the Smith chart of the network analyzer so that it can cope with the frequency of the noise generated from the signal generator. .
That is, in the matching circuit 103, each time the frequency of noise generated from the signal generator is changed, the circuit constant is determined again, and the resistor R1, the capacitors C1 and C2, and the inductors L1 and L2 are appropriately replaced. ing.

Japanese Patent Laying-Open No. 2006-234803 (FIGS. 1 to 5)

  Since the conventional noise injection device is configured as described above, when injecting noise of a specific frequency into the printed circuit board of the object to be measured, the circuit and constants consisting of the inductor and capacitor are measured through the measurement of the Smith chart of the network analyzer. It is necessary to make adjustments. For this reason, every time the frequency of the noise generated from the signal generator is changed, the circuit constant has to be determined again, and there is a problem that much time is required.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a noise injection device capable of easily injecting a noise signal of an arbitrary frequency into a power supply terminal of a component to be injected with noise. To do.

  In the noise injection device according to the present invention, the input side is connected to the noise injection connector, the matching circuit for matching the impedance between the input side and the output side, and one end is connected to the output side of the matching circuit. A variable capacity member that is switched to a capacity corresponding to the frequency of the noise signal generated from the signal source, and a first coil that has one end connected to the DC voltage input connector and the other end connected to the other end of the variable capacity member. A second coil whose one end is connected to the other end of the variable capacity member and the other end of the first coil, and a noise signal output from the other end of the second coil to a power supply terminal of a component to be injected with noise And a power supply terminal pin to be injected.

  According to the present invention, the input side is connected to the noise injection connector, the matching circuit for matching the impedance between the input side and the output side, and one end is connected to the output side of the matching circuit. A variable capacity member that can be switched to a capacity according to the frequency of the generated noise signal, a first coil that has one end connected to the DC voltage input connector and the other end connected to the other end of the variable capacity member, and one end For the second terminal connected to the other end of the variable capacity member and the other end of the first coil, and the power supply terminal for injecting the noise signal output from the other end of the second coil into the component to be injected with noise Since a pin is provided, there is an effect that a noise signal having an arbitrary frequency can be easily injected into a power supply terminal of a component to be injected with noise.

It is a perspective view which shows the noise injection apparatus by Embodiment 1 of this invention. 1 is an equivalent circuit diagram showing a noise injection device according to Embodiment 1 of the present invention. It is an equivalent circuit diagram which shows the variable capacity | capacitance member 14 of the noise injection apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the frequency of noise and noise injection amount. It is an equivalent circuit diagram which shows the variable capacity | capacitance member 14 of the noise injection apparatus by Embodiment 2 of this invention. It is the schematic which shows the noise injection apparatus which inject | pours noise into the printed circuit board of a to-be-measured object. It is explanatory drawing which shows that the noise injection apparatus is aiming at the impedance matching of the signal generator side and the printed circuit board side. It is a block diagram which shows the noise injection apparatus currently disclosed by patent document 1. FIG. FIG. 9 is an equivalent circuit diagram of the noise injection device of FIG. 8.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a noise injection apparatus according to Embodiment 1 of the present invention, and FIG. 2 is an equivalent circuit diagram showing the noise injection apparatus according to Embodiment 1 of the present invention.
1 and 2, a noise injection device 1 superimposes a noise signal generated from a noise signal source 2 on a DC voltage generated from a DC power source 5, and the DC voltage on which the noise is superimposed is a noise injection target component. It is a device that injects into the power supply terminal (for example, a low impedance circuit such as a printed circuit board of the object to be measured).
In FIG. 1, a noise injection connector 11, a DC voltage input connector 12, a matching circuit 13, a variable capacitance member 14, inductors 15 and 16, a power supply terminal pin 17, and a ground terminal pin that are components of the noise injection device 1. An example 18 is mounted on a printed circuit board.

The noise signal source 2 is a signal generator that generates a noise signal having a specific frequency.
The cable 3 is an electric wire such as a coaxial cable connecting the noise signal source 2 and the noise injection device 1, and 4 is a characteristic impedance of the cable 3.
The DC power source 5 is a power source that generates a DC voltage.
A cable 6 is an electric wire connecting the DC power source 5 and the noise injection device 1, and 7 is a characteristic impedance of the cable 6.

The noise injection connector 11 of the noise injection device 1 is a connection member that accommodates the cable 3 connected to the noise signal source 2.
The DC voltage input connector 12 is a connection member that accommodates the cable 6 connected to the DC power supply 5.
The matching circuit 13 is composed of, for example, a transformer capable of changing the winding ratio, and is a circuit for matching impedance between the noise injection connector 11 side on the input side and the variable capacitance member 14 side on the output side. It is.

One end of the variable capacitance member 14 is connected to the output side of the matching circuit 13 and is a circuit that can be switched to a capacitance corresponding to the frequency of the noise signal generated from the noise signal source 2.
The inductor 15 is a first coil having one end connected to the DC voltage input connector 12 and the other end connected to the other end of the variable capacitance member 14.
The inductor 16 is a second coil having one end connected to the other end of the variable capacitance member 14 and the other end of the inductor 15.

The power terminal pin 17 is provided at the end of the printed circuit board (the conductor connected to the other end of the inductor 16 extends to the end of the printed circuit board, and one end of the power terminal pin 17 is connected to the conductor. The side not connected to the conductor is a pin connected to the power supply pin connection terminal 8 in the power supply terminal of the noise injection target component.
The ground terminal pin 18 is provided in the ground 19 on the back side of the printed circuit board at a position close to the power terminal pin 17 and is connected to the ground of the component to be injected with noise.
The connection terminal 20 is a terminal for connecting the matching circuit 13 and the variable capacitance member 14, and the connection terminal 21 is a terminal for connecting the inductor 15 and the inductor 16.

  Between the noise injection connector 11 and the matching circuit 13, between the matching circuit 13 and the variable capacitance member 14, between the DC voltage input connector 12 and the inductor 15, between the inductor 15, the inductor 16 and the variable capacitance member 14, The inductor 16 and the power terminal pin 17 are each connected by a conductor.

FIG. 3 is an equivalent circuit diagram showing the variable capacitance member 14 of the noise injection device according to Embodiment 1 of the present invention.
3, the capacitor 31 has a capacitance of C _1, the output side is connected to the connection terminal 21.
The capacitor 32 has a capacitance of C ₂ different from the capacitance C ₁ of the capacitor 31, and the output side is connected to the connection terminal 21.
One end of the changeover switch 33 is connected to the connection terminal 20, and the other end is connected to the input terminal 31 a of the capacitor 31 or the input terminal 32 a of the capacitor 32 according to the frequency of the noise signal generated from the noise signal source 2. This is a member for setting the capacity of the variable capacity member 14 to C ₁ or C ₂ .

Next, the operation will be described.
When a DC voltage on which a noise signal is superimposed is injected into a power supply terminal of a noise injection target component which is a low impedance circuit (for example, a printed circuit board of a device under test), the noise signal source 2 is connected. The cable 3 is connected to the noise injection connector 11 of the noise injection device 1, and the cable 6 connected to the DC power source 5 is connected to the DC voltage input connector 12 of the noise injection device 1.
Further, the power supply terminal pin 17 of the noise injection device 1 is connected to the power supply pin connection terminal 8 (terminal connected to the power supply line of the noise injection target component) in the noise injection target component.
Further, the ground terminal pin 18 connected to the ground 19 on the back side of the printed board is connected to the ground of the component to be injected with noise.

As a result, the noise signal generated from the noise signal source 2 propagates through the cable 3 having the characteristic impedance 4 and is input to the noise injection connector 11 of the noise injection device 1.
At this time, the matching circuit 13 performs impedance matching between the noise injection connector 11 side and the variable capacitance member 14 side (impedance matching by the matching circuit 13 will be described later), thereby generating a noise signal generated from the noise signal source 2. Is input to the variable capacity member 14.

Thereby, the noise signal generated from the noise signal source 2 is input to the variable capacitance member 14, but when the frequency of the noise signal generated from the noise signal source 2 is switched to f1 or f2, the noise signal of the frequency f1 The capacity of the variable capacity member 14 suitable for injecting the noise is different from the capacity of the variable capacity member 14 suitable for injecting the noise signal having the frequency f2.
If the capacitance of the variable capacitance member 14 corresponds to the frequency of the noise signal, a sufficient noise injection amount can be ensured as shown in FIG. That is, a noise signal can be injected in a wide band.

Therefore, the variable capacitance element 14, a capacitor 31 of capacitance C ₁ suitable for injection of the noise signal of the frequency f1, and a capacitor 32 of capacitance C ₂ which are suitable for the injection of the noise signal of the frequency f2, generated from the noise signal source 2 when the frequency of the noise signal is f1 may be, the connection destination of the switch 33 is switched to the capacitor 31, the capacitance of the variable capacitance element 14 is to be set to C _1.
On the other hand, when the frequency of the noise signal generated from a noise signal source 2 is f2 is such that the connection of the changeover switch 23 is switched to the capacitor 32, the capacitance of the variable capacitance element 14 is set to C ₂ I have to.

However, the connection destination of the changeover switch 33 may be manually changed by the user, or may be automatically changed in conjunction with the frequency of noise generated from the noise signal source 2.
The noise signal output from the variable capacitance member 14 set to a capacity corresponding to the frequency of the noise signal is input to the power supply terminal pin 17 via the inductor 16 and injected from the power supply terminal pin 17. It is injected into the power line of the target component.
By switching the connection destination of the changeover switch 33, the resonance frequency of the capacitor of the variable capacity member 14 and the inductor 16 changes, so the frequency of the noise signal injected from the power supply terminal pin 17 to the power supply terminal of the component to be injected with noise. Bands are switched.

The DC voltage generated from the DC power source 5 is input from the DC voltage input connector 12 and input to the inductor 16 via the inductor 15.
Therefore, not only the noise signal output from the variable capacitor member 14 is injected into the noise injection target component, but the noise signal output from the variable capacitor member 14 is applied to the DC voltage generated from the DC power supply 5. The superimposed signal is injected.
Here, the inductor 15 is provided in order to prevent the noise signal output from the variable capacitance member 14 from propagating to the DC power supply 5 side by increasing the impedance at a desired frequency.

Thereby, the DC voltage on which the noise signal is superimposed is injected into the power supply terminal of the noise injection target component. However, at the stage of injecting the noise signal, the impedance on the variable capacitance member 14 side is indefinite.
For this reason, in order to ensure a sufficient noise injection amount, it is necessary to adjust the constant of the matching circuit 13 to optimize the impedance matching.
For example, by bringing a device (for example, a high impedance probe) capable of monitoring the amount of noise injection into contact with the power terminal pin 17, the matching circuit 13 is monitored while monitoring the amount of noise injection with respect to the noise injection target component. Is adjusted to ensure a sufficient noise injection amount for the component to be injected with noise.
When the matching circuit 13 includes a transformer that can change the winding ratio, the constant of the matching circuit 13 can be adjusted by adjusting the winding ratio of the transformer.
Therefore, it is not necessary to replace resistors and capacitors in the matching circuit as in the conventional example, and much labor is not required.

When a noise signal having a frequency of 1 MHz, for example, is injected, the inductance L _{1 of the} inductor 15, the capacitance C ₁ of the variable capacitance member 14, and the inductance L _{2 of the} inductor 16 are as follows.
When a noise signal having a frequency of 1 MHz is injected, the inductance L _{1 of the} inductor 15 becomes 79.5 μH so that the impedance of the inductor 15 becomes large (for example, Z = 500Ω) (see the following formula (1)). ).
Further, the capacitance C ₁ of the variable capacitance member 14 (the connection destination of the changeover switch 33 is the capacitor 31) is 159 nF so that the impedance of the variable capacitance member 14 becomes small (for example, Z = 1Ω) (the following equation (2) )).
Also, for resonating the variable capacitance element 14 and the inductor 16 at 1 MHz, (see the following formula (3)) of the inductance _{L 2} of the inductor 16 is 159MyuH.
Thereby, the 1 MHz noise signal output from the variable capacitance member 14 is injected into the power supply terminal of the component to be injected with noise without propagating to the DC power supply 5 side.

When a noise signal having a frequency of 2 MHz, for example, is injected, the inductance L _{1 of the} inductor 15, the capacitance C ₂ of the variable capacitance member 14, and the inductance L _{2 of the} inductor 16 are as follows.
When the frequency is injected 2MHz noise signal, so that the impedance of the inductor 15 is large (e.g., Z = 500 [Omega), the inductance _{L 1} of the inductor 15 is 39.7MyuH (see equation (1)).
Further, the capacitance C ₂ of the variable capacitance member 14 (the connection destination of the changeover switch 33 is the capacitor 32) is 79.5 nF so that the impedance of the variable capacitance member 14 becomes small (for example, Z = 1Ω) (the following equation) (See (4)).
Also, for resonating the variable capacitance element 14 and the inductor 16 at 2MHz, (see the following formula (5)) of the inductance _{L 2} of the inductor 16 is 79.5MyuH.
Thereby, the noise signal of 2 MHz output from the variable capacity member 14 is injected into the power supply terminal of the component to be injected with noise without propagating to the DC power supply 5 side.

  As apparent from the above, according to the first embodiment, the matching circuit 13 for matching the impedance between the noise injection connector 11 side and the variable capacitance member 14 side, and one end connected to the output side of the matching circuit 13 are connected. The variable capacity member 14 is switched to a capacity corresponding to the frequency of the noise signal generated from the noise signal source 2, one end is connected to the DC voltage input connector 12, and the other end is connected to the variable capacity member 14. The inductor 15 connected to the end, the inductor 16 connected at one end to the other end of the variable capacitance member 14 and the other end of the inductor 15, and the noise signal output from the other end of the inductor 16 to the noise injection target component Since the power supply terminal pin 17 to be injected into the power supply terminal is provided, each time the frequency of the noise signal is changed as in the conventional example, the matching frequency is changed. Without replacing the like resistors and capacitors in an effect that can be injected into the power supply terminal of the easy parts of the noise injection target noise signal having an arbitrary frequency.

  In the first embodiment, the case where the frequency of the noise signal generated from the noise signal source 2 is switched to f1 or f2 has been described. However, when the frequency is switched to three or more frequencies, the variable capacitance member 14 is used. Includes three or more capacitors having different capacities, and the changeover switch 33 is connected to one of the input terminals of the three or more capacitors according to the frequency of the noise signal generated from the noise signal source 2. What should I do?

Embodiment 2. FIG.
FIG. 5 is an equivalent circuit diagram showing the variable capacitance member 14 of the noise injection device according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
The changeover switch 34 has one end connected to the output terminal 31b of the capacitor 31 or the output terminal 32b of the capacitor 32 and the other end connected to the connection terminal 21 according to the frequency of the noise signal generated from the noise signal source 2. Thus, it is a member for setting the capacity of the variable capacity member 14 to C ₁ or C ₂ .

Next, the operation will be described.
Even the second embodiment, as in the first embodiment, the variable capacitance element 14, a capacitor 31 of capacitance C ₁ suitable for injection of the noise signal of the frequency f1, the capacitance C which are suitable for the injection of the noise signal of the frequency f2 ₂ capacitors 32.

When the frequency of the noise signal generated from a noise signal source 2 is f1, the changeover switch 34 is connected to the output terminal 31b of the capacitor 31, the capacitance of the variable capacitance element 14 is set to C _1.
On the other hand, in the case the frequency of the noise signal generated from a noise signal source 2 is f2, the changeover switch 34 is connected to the output terminal 32b of the capacitor 32, the capacitance of the variable capacitance element 14 is set to C ₂ .
The connection destination of the changeover switch 34 may be switched manually by the user, or may be switched automatically in conjunction with the frequency of noise generated from the noise signal source 2.

  In the case of the second embodiment, similarly to the first embodiment, even if the frequency of the noise signal generated from the noise signal source 2 can be changed, the noise signal can be easily supplied to the power supply terminal of the component to be injected with noise. The effect which can be inject | poured into is produced.

  In the second embodiment, the case where the frequency of the noise signal generated from the noise signal source 2 is switched to f1 or f2 is shown. However, when the frequency is switched to three or more frequencies, the variable capacitance member 14 is used. Includes three or more capacitors having different capacities, and the changeover switch 34 is connected to one of the output terminals of the three or more capacitors according to the frequency of the noise signal generated from the noise signal source 2. What should I do?

Embodiment 3 FIG.
In the first and second embodiments, the variable capacity member 14 is composed of a plurality of capacitors and a changeover switch. However, it is only necessary that the capacity can be varied. Alternatively, it may be composed of a variable capacitor.

  DESCRIPTION OF SYMBOLS 1 Noise injection apparatus, 2 Noise signal source, 3 Cable, 4 Cable 3 characteristic impedance, 5 DC power supply, 6 Cable, 7 Cable 6 characteristic impedance, 8 Power supply pin connection terminal, 11 Noise injection connector, 12 DC voltage Input connector, 13 matching circuit, 14 variable capacity member, 15 inductor (first coil), 16 inductor (second coil), 17 power terminal pin, 18 ground terminal pin, 19 ground, 20 connection terminal, 21 connection terminal, 31 capacitor, 31a capacitor 31 input terminal, 31b capacitor 31 output terminal, 32 capacitor, 32a capacitor 32 input terminal, 32b capacitor 32 output terminal, 33 selector switch, 34 selector switch, 101 SMA connector, 10 Copper, 103 matching circuit 104 ground connection copper plate, 105 wire, C1, C2 capacitor, R1 resistor, L1, L2 inductor.

Claims (6)

  A noise injection connector that accommodates a cable connected to a noise signal source that generates a noise signal, a DC voltage input connector that accommodates a cable connected to a DC power source that generates a DC voltage, and the input side is the above noise A matching circuit that is connected to the injection connector and that matches the impedance of the input side and the output side, and one end of the matching circuit that is connected to the output side of the matching circuit, the noise signal generated from the noise signal source A variable capacity member that can be switched to a capacity according to frequency, a first coil that has one end connected to the DC voltage input connector and the other end connected to the other end of the variable capacity member, and one end that is the variable capacity A second coil connected to the other end of the member and the other end of the first coil, and a noise signal output from the other end of the second coil are Noise injector having a pin power terminal to be injected into the power supply terminal of the injection target component.   The noise injection connector, DC voltage input connector, matching circuit, variable capacitance member, first coil, second coil, and power terminal pin are mounted on the printed circuit board. Noise injection device.   The variable capacity member includes a plurality of capacitors having different capacities, and a changeover switch having one end connected to the output side of the matching circuit and the other end connected to one of the input terminals of the plurality of capacitors. 3. The noise injection device according to claim 1, wherein the output sides of the plurality of capacitors are connected to the other end of the first coil and one end of the second coil.   The variable capacitance member is connected to a plurality of capacitors having different capacities, one end connected to one of the output terminals of the plurality of capacitors, and the other end connected to the other end of the first coil and one end of the second coil. 3. The noise injection device according to claim 1, wherein an input side of the plurality of capacitors is connected to an output side of the matching circuit.   By switching the connection destination of the changeover switch, the resonance frequency of the capacitor and the second coil is changed to switch the frequency band of the noise signal injected from the power supply terminal pin to the power supply terminal of the noise injection target component. The noise injection device according to claim 3 or 4, wherein the noise injection device is characterized in that:   3. The noise injection device according to claim 1, wherein the variable capacitance member is constituted by a varicap or a variable capacitor.

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