JP4067360B2 - Inspection apparatus and inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oscillation device having a plurality of oscillators each having a different oscillation frequency variable range. Set The present invention relates to an inspection apparatus and an inspection method for performing pass / fail determination.
[0002]
[Prior art]
A local frequency signal generator mounted in a transmission / reception device or the like has a plurality of voltage controlled oscillators (hereinafter referred to as VCO [Voltage Controlled Oscilator]) having different oscillation frequency variable ranges as their oscillation sources, Some can change the local frequency signal widely by switching each VCO as appropriate.
[0003]
The local frequency signal generator configured as described above cannot operate normally if the oscillation frequency variable regions of the VCOs are disconnected from each other. Therefore, at the time of product shipment or the like, it is necessary to inspect that the oscillation frequency variable regions of adjacent VCOs overlap each other at the end.
[0004]
Here, when the number of VCOs constituting the oscillation source is small (2, 3), the control voltage variable range of each VCO can be set sufficiently wide. In addition, since only a small number of external tank circuits determine the oscillation frequency of each VCO, adjustment of external constants (sizes of inductors and variable capacitance elements that constitute the tank circuit) does not significantly increase the circuit scale. It is also possible to give a margin to the overlapping range of the oscillation frequency variable range between the VCOs (see FIG. 14A).
[0005]
Therefore, in the inspection apparatus for inspecting the local frequency signal generator, the frequency variable range of each VCO is treated as fixed without depending on variations in circuit element constants and temperature / voltage fluctuations, and a common inspection frequency ft for each adjacent VCO. Can be set in advance, so that the pass / fail judgment can be easily and quickly performed. Further, as described above, since the overlapping range of the oscillation frequency variable region between adjacent VCOs has been given a margin, each VCO in the local frequency signal generator determined to pass has a poor sensitivity region (FIG. 15). It was rarely used in the reference).
[0006]
[Problems to be solved by the invention]
On the other hand, in recent years, a configuration in which each control voltage variable range is narrowed by increasing the VCO has been proposed in order to reduce the voltage of the local frequency signal generator. As described above, when there are a large number of VCOs constituting the oscillation source, a large number of external tank circuits are required for each VCO. Therefore, depending on the adjustment of the external constant, the circuit scale may be significantly increased. It is difficult to provide a sufficient margin for the overlapping range of the oscillation frequency variable region between adjacent VCOs. Further, as circuit integration progresses, variations in IC manufacturing processes increase, so the frequency variable range of each VCO is expected to vary greatly (see FIG. 14B).
[0007]
Therefore, since the inspection apparatus for inspecting the local frequency signal generator cannot handle the variable frequency range of each VCO as fixed, the conventional inspection method (inspection frequency is set for each adjacent VCO and the inspection frequency is set). If it is going to adopt the method of confirming whether or not both VCOs operate normally in this way, it is necessary to first find an appropriate inspection frequency for each adjacent VCO, set the inspection frequency one by one and start the inspection. First, there was a problem that it took a lot of time before the original inspection was performed. Further, as described above, since there is no allowance for the overlapping range of the oscillation frequency variable range between adjacent VCOs, depending on the setting of the inspection frequency, even if the local frequency signal generator determined to pass, each VCO However, there is a risk of being used in the sensitivity-insensitive region (see FIG. 15).
[0008]
It is possible to consider an inspection apparatus that prioritizes shortening of the inspection time and checks only whether the local frequency signal generator to be inspected normally operates at the minimum necessary arbitrary frequency. If the variation in each frequency variable region increases with the increase in the number, the pass / fail judgment may cause a problem.
[0009]
In view of the above-described problems, the present invention provides an inspection apparatus / inspection method capable of efficiently and reliably performing pass / fail determination of an oscillation device. The law The purpose is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an inspection apparatus according to the present invention is an inspection apparatus for performing pass / fail determination of an oscillation apparatus having a plurality of oscillators each having a different oscillation frequency variable range, wherein the output of the oscillation apparatus is at a desired frequency. A lock determination unit that determines whether or not a lock is detected, an end point detection unit that detects an end point frequency of an oscillation frequency variable region in each oscillator based on a determination result of the lock determination unit, and a detection result of the end point detection unit On the basis of this, the configuration includes an inspection processing unit that inspects that the oscillation frequency variable regions of the respective oscillators overlap each other at the end. By adopting such a configuration, it is possible to perform inspection more efficiently than conventional inspection apparatuses.
[0011]
In the inspection apparatus having the above-described configuration, the end point detection unit sequentially performs lock determination while changing the oscillation frequency so as to sandwich the end point frequency of the oscillation frequency variable region in each oscillator, and based on the determination result. The end point frequency may be detected. Alternatively, it may be configured to measure the time until the lock state is sequentially established while changing the oscillation frequency of each oscillator, and detect the end point frequency based on a comparison result between the measurement time and a predetermined time. By adopting such a configuration, it is possible to detect both end frequencies of the oscillation frequency variable range in each oscillator in a short time, so that the pass / fail judgment of the oscillation device performed based on the detection result is completed in a short time. Is possible.
[0012]
In the inspection apparatus having the above-described configuration, the lock determination unit may be configured such that the output of the oscillation device is in a locked state or an unlocked state when a reference signal from the oscillation device is maintained in the same state for a predetermined period. It may be configured to determine that there is. By adopting such a configuration, even when the reference signal becomes unstable in a sensitivity insensitive region of each oscillator, the possibility of making an erroneous lock determination is reduced.
[0013]
The inspection apparatus having the above-described configuration may be configured to shorten the time until the oscillation frequency is locked by setting the oscillation apparatus to be different from the actual use when detecting the end point frequency. By adopting such a configuration, it becomes possible to detect both end frequencies of the oscillation frequency variable range in each oscillator in a short time. Therefore, the pass / fail judgment of the oscillation device performed based on the detection result can also be performed in a short time. It can be completed.
[0014]
The inspection apparatus having the above-described configuration may be configured such that when the end point frequency is detected, the oscillation device is set differently from the actual use and the oscillation frequency variable range of each oscillator is narrowed. By adopting such a configuration, it is possible to strictly perform pass / fail determination of the oscillation device. Therefore, it is possible to reduce the possibility that each oscillator is used in a poor sensitivity region in the oscillation device determined to be acceptable.
[0015]
The inspection apparatus having the above-described configuration may be configured to detect the end point frequency by narrowing the oscillation frequency variable region of each oscillator, and then return to the original oscillation frequency variable region to perform lock determination at the end point frequency. By adopting such a configuration, it is possible to further improve the reliability of the oscillation device during actual use.
[0016]
The inspection apparatus having the above-described configuration may include a control voltage monitoring unit that monitors a control voltage for controlling the oscillation frequency of each oscillator and sends the monitoring result to the inspection processing unit. By adopting such a configuration, the control voltage value at the end point frequency when the oscillation frequency variable region is narrowed and the control voltage value when the oscillation frequency variable region is returned to the normal state therefrom are obtained by monitoring. Based on the amount of change between the two, it is possible to appropriately notify that there is a possibility that each oscillator may be used in a poor sensitivity region.
[0023]
In order to achieve the above object, an inspection method according to the present invention is an inspection method for performing pass / fail judgment of an oscillation device having a plurality of oscillators each having a different oscillation frequency variable range, wherein the output of the oscillation device is desired. Determine if locked by frequency Lock judgment Steps and the Lock judgment steps Detect the end point frequency of the oscillation frequency variable range in each oscillator based on the judgment result End point detection Steps and the Endpoint detection step Based on the detection result, check that the oscillation frequency variable range of each oscillator overlaps at the end Inspection process And a step. By adopting such a configuration, it is possible to perform the inspection more efficiently than the conventional inspection method.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing a first embodiment of a local frequency signal generator and an inspection device according to the present invention. The local frequency signal generator A of the present embodiment includes an oscillation circuit unit A1, a VCO selector A2, a phase locked loop circuit unit A3 (hereinafter referred to as a PLL [Phase-Locked-Loop] circuit unit A3), and selector control. Part A4.
[0025]
The oscillation circuit unit A1 is an oscillation source of the local frequency signal generator A, and includes n (n ≧ 2) VCOs 11 to 1n each having a different oscillation frequency variable range. The oscillation frequency of each of the VCOs 11 to 1n is variably controlled by the control voltage VT input from the PLL circuit unit A3.
[0026]
The VCO selector A2 selects any one of the oscillation signals generated by the VCOs 11 to 1n according to an instruction from the selector control unit A4, and outputs the oscillation signal to the outside of the apparatus as a local frequency signal LO.
[0027]
The PLL circuit unit A3 includes a prescaler 31 that divides the local frequency signal LO by a predetermined division ratio, a first frequency divider 32 that divides the output signal of the prescaler 31 by a division ratio according to the control signal, and a reference A reference oscillator 33 that generates an oscillation signal, a second frequency divider 34 that divides the output signal of the reference oscillator 33 by a frequency division ratio according to the control signal, and first and second frequency dividers 32 and 34, respectively. The phase comparison of the output frequency-divided signal is performed, a phase comparator 35 that outputs a pulse signal corresponding to the phase difference, the charge pump 36 that boosts the output signal of the phase comparator 35, and the output signal of the charge pump 36 And a loop filter 37 that generates the control voltage VT of the VCOs 11 to 1n. In the PLL circuit unit A3 configured as described above, feedback control is performed so that the phase difference between the frequency-divided signals of the first and second frequency dividers 32 and 34 is eliminated, and the local frequency signal LO is locked to a desired frequency. Is done.
[0028]
Further, the control voltage VT generated by the PLL circuit unit A3 is used not only for the oscillation frequency variable control of the VCOs 11 to 1n but also for the lock determination of the local frequency signal LO in the inspection apparatus B. As an external terminal for sending the control voltage VT to the inspection apparatus B, an external terminal that is used only during actual use and not used during inspection may be used. With such a configuration, the number of external terminals is not increased unnecessarily.
[0029]
The selector control unit A4 receives an instruction from the inspection device B at the time of inspection of the local frequency signal generator A and performs switching control of the VCO selector A2, and at the time of actual use, instructs from a frequency controller (not shown) of the set (transmission / reception device, etc.). In response, the switching control of the VCO selector A2 is performed.
[0030]
Note that the local frequency signal generator A of the present embodiment is a frequency controller that is set in actual use as an external terminal for connecting the inspection device B to the first and second frequency dividers 32 and 34 and the selector controller A4. The external terminals for connecting the parts 32, 34 and A4 are used. That is, when the local frequency signal generator A is inspected, the inspection device B is connected to the first and second frequency dividers 32 and 34 and the selector control unit A4 as shown in FIG. , 34, A4 is connected to the set frequency controller via the same terminal. With such a configuration, the number of external terminals is not increased unnecessarily.
[0031]
On the other hand, the inspection apparatus B of the present embodiment includes a lock determination unit B1, an end point detection unit B2, a frequency controller B3, a memory B4, an inspection processing unit B5, and a result notification unit B6.
[0032]
Based on the control voltage VT input from the local frequency signal generator A, the lock determination unit B1 determines whether the local frequency signal LO is locked at a desired frequency, and the determination result is sent to the end point detection unit B2. Send it out. In order to make a lock determination based on the control voltage VT, the lock determination unit B1 includes various arithmetic processing circuits and determination processing circuits (for example, an arithmetic processing circuit that calculates the rate of change of the control voltage VT, the rate of change and the experience). A determination processing circuit for performing lock determination by collating the law data).
[0033]
The end point detection unit B2 controls the frequency controller B3 based on the output signal of the lock determination unit B1, and detects both end frequencies of the oscillation frequency variable range in each of the VCOs 11 to 1n according to a procedure described in detail later. The end point detection unit B2 stores the data in the memory B4 each time the both end frequencies of the VCOs 11 to 1n are detected. When the end point detection is completed for all the VCOs, the end point detection unit B2 stores the data in the inspection processing unit B5. On the other hand, an instruction is sent to start the pass / fail inspection of the local frequency signal generator A based on the data stored in the memory B4.
[0034]
The frequency controller B3 controls the VCO selector A2 via the selector control unit A4 in accordance with an instruction from the end point detection unit B2, and designates any one of the VCOs 11 to 1n as an inspection target. Further, the frequency controller B3 sets the frequency division ratio of the first and second frequency dividers 32 and 34 in accordance with the instruction from the end point detection unit B2, and is designated as the inspection target according to the procedure detailed later. Transition the oscillation frequency of the VCO.
[0035]
The memory B4 is a storage unit that stores data passed from the end point detection unit B2 (detection data relating to both-end frequencies of the VCOs 11 to 1n) and sends data in response to a request from the inspection processing unit B5. Note that it is sufficient to provide a small-capacity RAM [Random Access Memory] as the memory B4, so that the device scale is not unnecessarily increased. In order to further reduce the scale of the apparatus, a part of work RAM (not shown) necessary for the overall logic operation of the apparatus may be used.
[0036]
The inspection processing unit B5 reads the data stored in the memory B4 according to the instruction from the end point detection unit B2, and based on the stored data, the oscillation frequency variable regions of the oscillators VCO11 to 1n overlap each other at the end. Inspect. And based on this test result, the pass / fail determination of the local frequency signal generator A is performed. Specifically, the inspection processing unit B5 compares the upper frequency of the low frequency side VCO and the lower frequency of the high frequency side VCO for each adjacent VCO, and the low frequency side VCO for all combinations. If the upper end frequency of the VCO is higher than the lower end frequency of the high frequency side VCO, the oscillation frequency variable range of each VCO is considered to be continuous while overlapping each other, and the pass determination is performed. On the other hand, if there is at least one combination in which the upper frequency of the low frequency side VCO is lower than the lower frequency of the high frequency side VCO, the oscillation frequency variable range of each VCO is considered to be disconnected somewhere, and a failure determination is made. I do. In addition, the pass / fail determination result obtained by the inspection processing unit B5 is sent to the result notification unit B6.
[0037]
The result notifying unit B6 is a means for notifying the inspector of the pass / fail determination result obtained by the inspection processing unit B5. The specific configuration of the result notification unit B6 may be a visual notification unit such as a liquid crystal display, a monitor, or a light emitting diode, or an auditory notification unit such as a buzzer or a speaker. If an interface unit for transmitting the pass / fail judgment result to the outside is provided in place of the result notifying unit B6, the pass / fail judgment result can be managed by a computer outside the apparatus. It is possible to construct a shipping inspection system that performs automatic classification based on judgment.
[0038]
As described above, the inspection apparatus B of the present embodiment is a conventional inspection apparatus (inspection of a system in which an inspection frequency is set for each adjacent VCO and whether or not both VCOs normally operate at the inspection frequency). Unlike the apparatus, the both-end frequencies of the oscillation frequency variable regions of the VCOs 11 to 1n are detected, and the detection results are combined to determine the pass / fail of the local frequency signal generator A. By adopting such a configuration, it is possible to perform inspection more efficiently than conventional inspection apparatuses.
[0039]
In the above description, the frequency of both ends of the VCOs 11 to 1n is detected and the pass / fail judgment of the local frequency signal generator A is taken as an example based on the detection result. However, the configuration of the present invention is not limited to this. For example, for VCOs in which every other end point detection of each of the VCOs 11 to 1n is performed and end point detection is not performed, only the operation check at the upper end frequency and the lower end frequency detected by the preceding and following VCOs is performed. It is good also as composition which performs. With such a configuration, it is possible to further speed up the inspection.
[0040]
In addition, the lock determination unit B1, the end point detection unit B2, and the inspection processing unit B5 that constitute the inspection apparatus B may each be configured by hardware, or the operation of each unit may be realized by software. .
[0041]
Subsequently, the end point detection method for each of the VCOs 11 to 1n in the end point detection unit B2 will be described in detail.
[0042]
First, the first endpoint detection method will be described in detail with reference to FIGS. FIG. 2 is a flowchart showing the procedure of the first endpoint detection method, and FIG. 3 is a diagram schematically showing an example of setting the VCO oscillation frequency in the first endpoint detection method. In this method, lock determination is performed sequentially while changing the oscillation frequency so that the end frequency of the oscillation frequency variable range in each oscillator VCO 11 to 1n is sandwiched, and the end point of each VCO 11 to 1n is determined based on the determination result. It is the structure to detect.
[0043]
In the inspection apparatus B employing this method, first, in step S105, the oscillation frequency of the inspection target VCO is set by the frequency controller B3. Here, the oscillation frequency of the inspection target VCO is set outside the variable range (low frequency fo). In step S110, after a predetermined time (a time sufficient for the oscillation frequency of the inspection target VCO to be locked by the PLL circuit unit A3) waits, in step S115, the inspection target by the lock determination unit B1. VCO lock determination is performed.
[0044]
If it is determined in step S115 that the oscillation frequency of the inspection target VCO is not in the locked state, the flow proceeds to step S120. In step S120, the end point detection unit B2 instructs the frequency controller B3 to step up the oscillation frequency. Then, the frequency controller B3 that has received the instruction controls the frequency division ratios of the first and second frequency dividers 32 and 34, and the oscillation frequency of the inspection target VCO is increased by the shift amount Sa from the current level. Thereafter, the flow is returned to step S110, and the lock determination of the inspection target VCO at the oscillation frequency is repeated. That is, in this loop operation, the oscillation frequency of the inspection target VCO is stepped up by the shift amount Sa until the lock determination unit B1 detects the lock state.
[0045]
On the other hand, when the oscillation frequency of the inspection target VCO reaches within the variable range (above the lower end frequency) by the above loop operation, the inspection target VCO is locked at the oscillation frequency, so a YES determination is made in step S115, and the flow Advances to step S125. In step S125, the endpoint detection unit B2 instructs the frequency controller B3 to step down the oscillation frequency. Then, the frequency controller B3 that receives the instruction controls the frequency division ratios of the first and second frequency dividers 32 and 34, and the oscillation frequency of the inspection target VCO is shifted from the current state by the shift amount Sb (Sb <Sa, for example, It is lowered by Sb = Sa / 2). Thereafter, after the elapse of a predetermined time in step S130, the lock determination unit B1 determines whether or not the inspection target VCO is locked in step S135.
[0046]
If it is determined in step S135 that the oscillation frequency of the inspection target VCO is not unlocked, the flow returns to step S125, and the oscillation frequency is stepped down and the lock determination is repeated. That is, in this loop operation, the oscillation frequency of the inspection target VCO is stepped down by the shift amount Sb until the unlock state is detected by the lock determination unit B1.
[0047]
On the other hand, when the oscillation frequency of the inspection target VCO reaches the outside of the variable range (below the lower end frequency) by the loop operation, the inspection target VCO is unlocked at the oscillation frequency, so a YES determination is made in step S135. The flow proceeds to step S140. In step S140, the oscillation frequency set immediately before unlocking is adopted as the lower end frequency fa of the inspection target VCO, and the data is stored in the memory B4.
[0048]
After the detection of the lower end frequency fa in steps S105 to S140, in the subsequent step S145, the end point detection unit B2 instructs the frequency controller B3 to step up the oscillation frequency again. Then, the frequency controller B3 that has received the instruction controls the frequency division ratios of the first and second frequency dividers 32 and 34, and the oscillation frequency of the inspection target VCO is increased by the shift amount Sa from the current level. Then, after the elapse of a predetermined time in step S150, the lock determination unit B1 determines whether or not the inspection target VCO is locked in step S155.
[0049]
If it is determined in step S155 that the oscillation frequency of the inspection target VCO is not unlocked, the flow is returned to step S145, and the oscillation frequency is stepped up and the lock determination is repeated. That is, in this loop operation, the oscillation frequency of the inspection target VCO is stepped up by the shift amount Sa until the unlock state is detected by the lock determination unit B1.
[0050]
On the other hand, when the oscillation frequency of the inspection target VCO reaches the outside of the variable range (above the upper end frequency) by the loop operation, the inspection target VCO is unlocked at the oscillation frequency, so a YES determination is made in step S155. The flow proceeds to step S160. In step S160, the end point detection unit B2 instructs the frequency controller B3 to step down the oscillation frequency. In response to the instruction, the frequency controller B3 controls the frequency division ratios of the first and second frequency dividers 32 and 34, and the oscillation frequency of the inspection target VCO is reduced by the shift amount Sb from the current level. Then, after the elapse of a predetermined time in step S165, the lock determination unit B1 performs lock determination of the inspection target VCO in step S170.
[0051]
If it is determined in step S170 that the oscillation frequency of the inspection target VCO is not locked, the flow returns to step S160, and the oscillation frequency is stepped down and the lock determination is repeated. That is, in this loop operation, the oscillation frequency of the inspection target VCO is stepped down by the shift amount Sb until the lock determination unit B1 detects the lock state.
[0052]
On the other hand, when the oscillation frequency of the inspection target VCO reaches within the variable range (below the upper end frequency) by the above loop operation, the inspection target VCO is locked at the oscillation frequency. Advances to step S175. In step S175, the current oscillation frequency reaching the lock is adopted as the upper end frequency fb of the inspection target VCO, and the data is stored in the memory B4.
[0053]
After the detection of the upper end frequency fb in steps S145 to S175, the end point detection unit B2 sends an instruction to the frequency controller B3 to continue detection of both end frequencies using another VCO as an inspection target.
[0054]
In this way, the lock determination is sequentially performed while the oscillation frequency is converged and changed so as to sandwich the end point frequency of the oscillation frequency variable range in each oscillator VCO 11 to 1n, and the end point of each VCO 11 to 1n is detected based on the determination result. If the method is used, it is possible to detect both end frequencies of the oscillation frequency variable range in each VCO 11 to 1n in a short time, and therefore the pass / fail judgment of the local frequency signal generator A performed based on the detection result is completed in a short time. It becomes possible to do.
[0055]
In the above embodiment, the description has been given by taking as an example the configuration in which the oscillation frequency is stepped up and down once each time when detecting the one end point. A similar step-up / step-down may be repeated multiple times. By adopting such a configuration, the detected end point frequency converges to a true value, so that the detection accuracy can be increased.
[0056]
Next, the second endpoint detection method will be described in detail with reference to FIGS. FIG. 4 is a flowchart showing the procedure of the second end point detection method, and FIG. 5 shows the correlation between the VCO oscillation frequency and the lock time (the time required to determine the lock state after setting the oscillation frequency). FIG. Note that this method measures the lock time sequentially while changing the oscillation frequency of each oscillator VCO 11 to 1n in view of the fact that the lock time is longer near both ends of the VCO oscillation frequency (insensitive sensitivity region; see FIG. 15). In this configuration, the end points of the VCOs 11 to 1n are detected based on the comparison result between the lock time and the predetermined time.
[0057]
In the inspection apparatus B employing this method, first, in step S205, the oscillation frequency of the inspection target VCO is set by the frequency controller B3. In the present embodiment, the oscillation frequency of the inspection target VCO is set within the variable range (frequency fo).
[0058]
In subsequent step S210, the lock time t is measured by the end point detection unit B2 based on the lock determination of the inspection target VCO by the lock determination unit B1. In the lock determination unit B1 of the present embodiment, the lock determination is not performed at an instant after a predetermined time has elapsed from the frequency setting, but from the time of the frequency setting until the oscillation frequency of the inspection target VCO is locked. The lock determination is continuously performed.
[0059]
When the lock time t is measured in step S210, in the subsequent step S215, the end point detection unit B2 requires the lock time t and a predetermined reference time tc (until the oscillation frequency is locked in the insensitive region of the inspection target VCO). Comparison with the expected time) is performed. If it is determined that the lock time t is shorter than the reference time tc, the flow proceeds to step S220.
[0060]
In step S220, the end point detection unit B2 instructs the frequency controller B3 to step down the oscillation frequency. Then, the frequency controller B3 that has received the instruction controls the frequency division ratios of the first and second frequency dividers 32 and 34, and the oscillation frequency of the inspection target VCO is lowered by a predetermined shift amount from the current state. Thereafter, the flow returns to step S210, and the lock determination at the oscillation frequency is repeated. That is, in this loop operation, the oscillation frequency of the inspection target VCO is stepped down by a predetermined shift amount until the lock time t exceeds the reference time tc.
[0061]
On the other hand, when the oscillation frequency of the inspection target VCO reaches outside the variable range (below the lower end frequency) by the loop operation, the lock time t exceeds the reference time tc, so a YES determination is made in step S215, and the flow proceeds to step S225. Proceed to In step S225, the oscillation frequency set immediately before is adopted as the lower end frequency fa of the inspection target VCO, and the data is stored in the memory B4.
[0062]
After the detection of the lower end frequency fa in steps S205 to S225, in step S230, the frequency controller B3 sets the oscillation frequency of the inspection target VCO again within the variable range (frequency fo). In subsequent step S235, the lock time t is measured by the end point detection unit B2 based on the lock determination of the inspection target VCO by the lock determination unit B1.
[0063]
When the lock time t is measured in step S235, in the subsequent step S240, the end point detection unit B2 compares the lock time t with a predetermined reference time tc. Here, if it is determined that the lock time t is shorter than the reference time tc, the flow proceeds to step S245.
[0064]
In step S245, the end point detection unit B2 instructs the frequency controller B3 to step up the oscillation frequency. Then, the frequency controller B3 that has received the instruction controls the frequency division ratios of the first and second frequency dividers 32 and 34, and the oscillation frequency of the inspection target VCO is increased by a predetermined shift amount from the current state. Thereafter, the flow returns to step S235, and the lock determination at the oscillation frequency is repeated. That is, in this loop operation, the oscillation frequency of the inspection target VCO is stepped up by a predetermined shift amount until the lock time t exceeds the reference time tc.
[0065]
On the other hand, when the oscillation frequency of the inspection target VCO reaches outside the variable range (above the upper end frequency) by the loop operation, the lock time t exceeds the reference time tc, so a YES determination is made in step S240, and the flow proceeds to step S250. Proceed to In step S250, the oscillation frequency set immediately before is adopted as the upper end frequency fb of the inspection target VCO, and the data is stored in the memory B4.
[0066]
After the detection of the upper end frequency fb in steps S230 to S250, the end point detection unit B2 sends an instruction to the frequency controller B3 to continue detection of both end frequencies using another VCO as an inspection target.
[0067]
As described above, the lock time is sequentially measured while changing the oscillation frequency of each oscillator VCO 11 to 1n, and the end point of each VCO 11 to 1n is detected based on the comparison result between the lock time and the predetermined time. Since both end frequencies of the oscillation frequency variable range in each VCO 11 to 1n can be detected in a short time, the pass / fail judgment of the local frequency signal generator A performed based on the detection result can be completed in a short time. Become.
[0068]
In the above embodiment, the description has been given by taking as an example a configuration in which both end detection is started from within the oscillation frequency variable region of the inspection target VCO. However, the configuration of the present invention is not limited to this, and the configuration outside the oscillation frequency variable region is described. It is also possible to start from both ends detection. However, since the oscillation frequency of the inspection target VCO is not locked outside the oscillation frequency variable range and it takes a long time to detect the lock time, it can be said that it is desirable to adopt this configuration if more rapid detection of both ends is desired.
[0069]
Next, a second embodiment of the present invention will be described. FIG. 6 is a block diagram showing a second embodiment of the local frequency signal generator and the inspection device according to the present invention. The present embodiment is a configuration obtained by improving the first embodiment, and the configuration and operation thereof are substantially the same as those of the first embodiment. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals as those in FIG. 1, and the description thereof is omitted. In the following, the characteristic part of this embodiment (the lock frequency detection signal generator A5 is added to the local frequency signal generator A). We will give an emphasis on the points).
[0070]
The lock detection signal generation unit A5 determines whether or not each output signal of the first and second frequency dividers 32 and 34 satisfies a predetermined condition (for example, whether or not both phase differences are continuously within a predetermined range). ) And a lock detection signal LD (a high-level / low-level binary signal) indicating whether or not the local frequency signal LO is locked at a desired frequency is generated based on the monitoring result.
[0071]
The generated lock detection signal LD is sent to the lock determination unit B1 of the inspection apparatus B, and is used for lock determination of the inspection target VCO. Therefore, unlike the first embodiment in which the lock determination unit B1 that receives the lock detection signal LD performs the lock determination based on the control voltage VT, the lock determination unit B1 only needs to confirm the output level of the lock detection signal LD to detect the local frequency signal LO. Can be determined whether or not is locked at the desired frequency.
[0072]
By adopting such a configuration, the lock determination unit B1 can be simplified as compared with the first embodiment in which the lock determination is performed based on the control voltage VT, so that the scale reduction of the inspection apparatus B can be realized. Is possible. As described above, the lock detection signal generation unit A5 only monitors whether or not the phase difference between the output signals of the first and second frequency dividers 32 and 34 is continuously within a predetermined range. Therefore, the addition of the lock detection signal generator A5 does not cause an increase in the size of the local frequency signal generator A.
[0073]
In addition, the lock determination unit B1 of the present embodiment determines that the local frequency signal LO is in the locked state (or unlocked state) when the output level of the lock detection signal LD continues for a predetermined period and maintains the same state. It is configured to do. With such a configuration, even when the output level of the lock detection signal LD becomes unstable in the poor sensitivity region (see FIG. 15) of the inspection target VCO, the lock state may be erroneously determined. Less.
[0074]
As an external terminal for sending the lock detection signal LD to the inspection device B, an external terminal that is used only during actual use and not used during inspection may be used. With such a configuration, the number of external terminals is not increased unnecessarily.
[0075]
In addition, the local frequency signal generator A of the present embodiment is configured to send the lock detection signal LD generated by the lock detection signal generator A5 to the selector controller A4. With this configuration, the local frequency signal generator A can autonomously select a VCO as necessary.
[0076]
In the above embodiment, the configuration in which the lock detection signal generator A5 is provided in the local frequency signal generator A has been described as an example. However, the configuration of the present invention is not limited to this, and the same The lock detection signal generator may be provided in the inspection apparatus B.
[0077]
Next, a third embodiment of the present invention will be described. FIG. 7 is a block diagram showing a third embodiment of the local frequency signal generator and the inspection device according to the present invention. This embodiment is a configuration obtained by improving the above-described second embodiment, and the configuration and operation thereof are substantially the same as those of the second embodiment. Therefore, the same parts as those in the second embodiment are denoted by the same reference numerals as those in FIG. 6, and the description thereof will be omitted. I will give an explanation with emphasis on the points that can be controlled.
[0078]
As described above, the local frequency signal generator A according to the present embodiment can control the drive current of the charge pump 36 and the circuit constants of the loop filter 37 constituting the PLL circuit unit A3 in accordance with an instruction from the inspection device B. This is the configuration. With such a configuration, when the local frequency signal generator A is inspected, the driving current of the charge pump 36 and the circuit constants of the loop filter 37 (that is, the pulse output period of the phase comparator 35 and the cutoff frequency of the loop filter 37). ) Can be set differently from actual use to shorten the lock time. Accordingly, since both end frequencies of the oscillation frequency variable region in each VCO 11 to 1n can be detected in a short time, the pass / fail judgment of the local frequency signal generator A performed based on the detection result is completed in a short time. It becomes possible to do.
[0079]
Next, a fourth embodiment of the present invention will be described. FIG. 8 is a block diagram showing a fourth embodiment of a local frequency signal generator and an inspection device according to the present invention. This embodiment is a configuration obtained by improving the above-described third embodiment, and the configuration and operation thereof are substantially the same as those of the third embodiment. Therefore, the same parts as those in the third embodiment are denoted by the same reference numerals as those in FIG. 7, and the description thereof is omitted. Hereinafter, the characteristic part of this embodiment (the oscillation frequency variable range of the VCOs 11 to 1n can be controlled). ) Will be explained with emphasis.
[0080]
As described above, the local frequency signal generator A according to the present embodiment is configured to be able to control the oscillation frequency variable region of the VCOs 11 to 1n constituting the oscillation circuit unit A1 in accordance with an instruction from the inspection device B. By adopting such a configuration, both ends of the oscillation frequency variable range can be detected in a state where the oscillation frequency variable range of each VCO 11 to 1n is temporarily narrowed (see FIG. 9). The pass / fail judgment of the frequency signal generator A can be performed strictly. Therefore, in the local frequency signal generator A determined to be acceptable, it is possible to reduce the possibility that the VCOs 11 to 1n are used in the poor sensitivity region (see FIG. 15).
[0081]
Note that the local frequency signal generator A can be configured by narrowing the oscillation frequency variable region of each of the VCOs 11 to 1n to detect the end point frequency and then returning the oscillation frequency variable region to the original state to perform lock determination at the end point frequency. It is possible to further improve the reliability during actual use. Further, if the end point frequency is detected by narrowing the oscillation frequency variable range, and then the end point frequency is detected again by returning the oscillation frequency variable range, a part of the oscillation frequency variable range in each VCO is referred to. It is possible to confirm whether or not the frequency variable range control function in the present embodiment is operating normally.
[0082]
Next, a specific configuration of the VCOs 11 to 1n that can control the oscillation frequency variable range will be described. FIG. 10 is a circuit diagram showing a configuration example of the VCOs 11 to 1n in the fourth embodiment. FIG. 4A shows a general VCO having a fixed oscillation frequency variable range, and FIG. 4B shows a VCO whose oscillation frequency variable range can be controlled.
[0083]
As shown in FIG. 2A, a general VCO having a fixed oscillation frequency variable range is an active circuit composed of inductors La and Lb and variable capacitance elements VCa and VCb, and npn transistors Qa and Qb. A circuit (negative resistance circuit) and a constant current source I. As the variable capacitance elements VCa and VCb, a variable capacitance diode, a gate capacitance of a MOS field effect transistor, or the like is generally used.
[0084]
One end of each of the inductors La and Lb is connected to the power supply voltage line, and the other end is connected to each collector of the transistors Qa and Qb. The emitters of the transistors Qa and Qb are connected to each other, and the connection node is grounded via a constant current source. The bases of the transistors Qa and Qb are connected to the collectors of each other. The variable capacitance elements VCa and VCb are connected in series between the collectors of the transistors Qa and Qb, and a control voltage VT is applied to a connection node between the variable capacitance elements VCa and VCb.
[0085]
In the VCO configured as described above, when the control voltage VT applied to the connection node of the variable capacitance elements VCa and VCb is changed, the voltage applied to the variable capacitance elements VCa and VCb changes, and the variable capacitance elements VCa and VCb have different voltages. The capacity changes. Therefore, by changing the control voltage VT, the resonance frequency of the resonance circuit including various parasitic elements (that is, the oscillation frequency of the VCO) can be changed. However, in this configuration, since the variable capacitance width of the variable capacitance elements VCa and VCb is fixed, the VCO oscillation frequency variable range is also fixed.
[0086]
On the other hand, as shown in FIG. 5B, the VCO of the present embodiment capable of controlling the oscillation frequency variable region is replaced with six variable capacitance elements VCa1 to VCa1 instead of the variable capacitance elements VCa and VCb having the above-described configuration. VCa3, VCb1 to VCb3, and two switch circuits SW1, SW2. These variable capacitance elements are divided into three sets as shown in the figure, and are connected in parallel between the collectors of the transistors Qa and Qb. Note that the total capacitances of the variable capacitance elements VCa1 to VCa3 and VCb1 to VCb3 are adjusted to be equal to the capacitances of the variable capacitance elements VCa and VCb, respectively.
[0087]
A control voltage VT is directly applied to the connection node of the variable capacitance elements VCa1 and VCb1. One of the control voltage VT and the power supply voltage is selectively applied by the switch circuit SW1 to the connection node of the variable capacitance elements VCa2 and VCb2. Either the control voltage VT or the ground voltage is selectively applied by the switch circuit SW2 to the connection node of the variable capacitance elements VCa3 and VCb3. The switch circuits SW1 and SW2 are configured by field effect transistors or the like, and the switching operation is controlled by the inspection apparatus B.
[0088]
In the VCO configured as described above, if the control voltage VT is applied to both connection nodes of the variable capacitance elements VCa2 and VCb2 and the variable capacitance elements VCa3 and VCb3, this configuration becomes equivalent to FIG. The oscillation frequency variable region of the VCO is in a normal state. On the other hand, if a power supply voltage is applied to the connection node of the variable capacitance elements VCa2 and VCb2, the variable capacitance elements VCa2 and VCb2 are not controlled by the control voltage VT, so that the oscillation frequency variable range (low side) of the VCO is limited. Is done. Similarly, if the connection node of the variable capacitance elements VCa3 and VCb3 is grounded, the variable capacitance elements VCa3 and VCb3 are not controlled by the control voltage VT, so that the oscillation frequency variable range (high frequency side) of the VCO is limited. . Note that the voltage applied to the connection node of the variable capacitance elements VCa2 and VCb2 only needs to be a voltage corresponding to the upper limit of the frequency, and thus does not necessarily have to be the power supply voltage.
[0089]
Next, a fifth embodiment of the present invention will be described. FIG. 11 is a block diagram showing a fifth embodiment of a local frequency signal generator and an inspection device according to the present invention. This embodiment is a configuration obtained by improving the above-described fourth embodiment, and the configuration and operation thereof are substantially the same as those of the fourth embodiment. Therefore, the same parts as those in the fourth embodiment are denoted by the same reference numerals as those in FIG. 8, and the description thereof is omitted. Hereinafter, the characteristic parts of the present embodiment (the control voltage VT is monitored by the inspection apparatus B). We will give an explanation with emphasis on.
[0090]
As described above, the inspection apparatus B of the present embodiment has the control voltage monitor unit B7 that monitors the control voltage VT for controlling the oscillation frequency of the VCOs 11 to 1n and sends the monitoring result to the inspection processing unit B5. It consists of The local frequency signal generator A may be configured to use an external terminal that is used only during actual use and not used during inspection as an external terminal that sends the control voltage VT to the inspection device B. With such a configuration, the number of external terminals is not increased unnecessarily.
[0091]
The operation of the control voltage monitor unit B7 will be described in detail with reference to FIG. FIG. 12 is a diagram showing the correlation between the control voltage VT and the VCO oscillation frequency. Note that the solid line in the figure shows the case where the variable frequency range of the VCO is in the normal state, and the broken line shows the case where the lower end of the variable frequency range of the VCO is narrowed.
[0092]
When the control voltage monitor unit B7 narrows the oscillation frequency variable region of the VCO and detects the control voltage value Va at the end point frequency (here, the lower end frequency fa), and then returns the oscillation frequency variable region of the VCO to the normal state. The control voltage value Vb is monitored to obtain a change amount ΔVT (= | Va−Vb |) of the control voltage VT, and the monitoring result is sent to the inspection processing unit B5. The inspection processing unit B5 issues a result notification instruction to the result notification unit B6 based on the change amount ΔVT in view of the fact that the change amount ΔVT increases as the change amount ΔVT becomes closer to the VCO insensitive region.
[0093]
By adopting such a configuration, for example, when the change amount ΔVT exceeds a predetermined value, even if the local frequency signal generator A is determined to be acceptable, each of the VCOs 11 to 1n is in a poor sensitivity region ( It is possible to appropriately notify that there is a risk of being used in (see FIG. 15). Therefore, the inspector of the local frequency signal generator A that has received the notification can quickly take appropriate measures (such as restricting the frequency variable range and canceling the pass determination).
[0094]
In the above embodiment, the detailed description has been given by taking as an example the case where the control voltage monitor B7 is provided in the inspection apparatus B. However, the control voltage monitor B7 is incorporated in the local frequency signal generator A. It doesn't matter. In that case, the control voltage monitoring unit may be configured to include a comparator that generates a comparison signal (a high-level / low-level binary signal) corresponding to the magnitude relationship between the change amount ΔVT of the control voltage VT and a predetermined threshold value. By adopting such a configuration, it is inspected whether each VCO 11 to 1n may be used in a poor sensitivity area (see FIG. 15) by using a logic tester generally used in other inspections. Therefore, the inspection equipment cost is not increased unnecessarily.
[0095]
Next, a sixth embodiment of the present invention will be described. FIG. 13 is a block diagram showing a sixth embodiment of a local frequency signal generator and an inspection device according to the present invention. This embodiment is a configuration obtained by improving the above-described fifth embodiment, and the configuration and operation thereof are substantially the same as those of the fifth embodiment. Therefore, the same parts as those in the fourth embodiment are denoted by the same reference numerals as those in FIG. 11, and the description thereof will be omitted. Hereinafter, the characteristic parts of this embodiment (the local frequency signal generator A is provided with a serial bus interface) ) Will be explained with emphasis.
[0096]
As described above, the local frequency signal generator A of the present embodiment has the register A6 that functions as a serial bus interface. The register A6 temporarily stores the input serial control signal and then converts it into a parallel control signal. The parallel control signal is converted into a VCO 11 to 1n, first and second frequency dividers 32 and 34, a charge pump 36, and a loop filter. 37 and the selector control unit A4.
[0097]
By adopting such a configuration, the local frequency signal generator A and the inspection device B can be connected by a serial bus, so that the number of external terminals can be greatly reduced. As a serial bus connecting both devices A and B, the number of external terminals can be two lines, a data line and a clock line. ² A C bus may be used. Especially for satellite broadcast receivers, etc. ² Since the C bus is adopted as a standard, the local frequency signal generator A mounted in such a device has its I ² What is necessary is just to set it as the structure which uses C bus | bath.
[0098]
【The invention's effect】
As described above, according to the present invention, an inspection apparatus / inspection method that can efficiently and reliably perform pass / fail determination of an oscillation device. The law Can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a local frequency signal generator and an inspection device according to the present invention.
FIG. 2 is a flowchart showing a procedure of a first end point detection method.
FIG. 3 is a diagram schematically illustrating a setting example of a VCO oscillation frequency in the first end point detection method.
FIG. 4 is a flowchart showing a procedure of a second endpoint detection method.
FIG. 5 is a diagram showing a correlation between a VCO oscillation frequency and a lock time.
FIG. 6 is a block diagram showing a second embodiment of a local frequency signal generator and an inspection device according to the present invention.
FIG. 7 is a block diagram showing a third embodiment of a local frequency signal generator and an inspection device according to the present invention.
FIG. 8 is a block diagram showing a fourth embodiment of a local frequency signal generator and an inspection device according to the present invention.
FIG. 9 is a diagram showing a state (lower side only) where the oscillation frequency variable region of the VCO is temporarily narrowed.
FIG. 10 is a circuit diagram showing a configuration example of VCOs 11 to 1n in the fourth embodiment.
FIG. 11 is a block diagram showing a fifth embodiment of a local frequency signal generator and an inspection device according to the present invention.
FIG. 12 is a diagram showing a correlation between a control voltage VT and a VCO oscillation frequency.
FIG. 13 is a block diagram showing a sixth embodiment of a local frequency signal generator and an inspection device according to the present invention.
FIG. 14 is a diagram illustrating an example of a VCO oscillation frequency variable range.
FIG. 15 is a diagram showing a correlation between a control voltage and a VCO oscillation frequency.
[Explanation of symbols]
A Local frequency signal generator
A1 Oscillator circuit
11 to 1n Voltage controlled oscillator (VCO)
A2 VCO selector
A3 Phase lock loop circuit (PLL circuit)
31 Prescaler
32 First frequency divider
33 Reference oscillator
34 Second divider
35 Phase comparator
36 Charge pump
37 Loop filter
A4 Selector control unit
A5 Lock detection signal generator (LD generator)
A6 register
B inspection equipment
B1 Lock judgment part
B2 Endpoint detection unit
B3 frequency controller
B4 memory
B5 Inspection processing department
B6 result notification section
B7 Control voltage monitor (VT monitor)

Claims (9)

  An inspection device for performing pass / fail determination of an oscillation device having a plurality of oscillators each having a different oscillation frequency variable range, wherein the lock determination unit determines whether or not the output of the oscillation device is locked at a desired frequency, and the lock An end point detection unit that detects the end point frequency of the oscillation frequency variable range in each oscillator based on the determination result of the determination unit, and the oscillation frequency variable range of each oscillator overlaps at the end based on the detection result of the end point detection unit. And an inspection processing unit for inspecting the inspection device.   The end point detection unit sequentially performs lock determination while converging and changing the oscillation frequency so as to sandwich the end point frequency of the oscillation frequency variable region in each oscillator, and detects the end point frequency based on the determination result. The inspection apparatus according to claim 1.   The end point detection unit measures the time until the lock state is sequentially changed while changing the oscillation frequency of each oscillator, and detects the end point frequency based on a comparison result between the measurement time and a predetermined time. The inspection apparatus according to claim 1.   The lock determination unit determines that the output of the oscillation device is in a locked state or an unlocked state when a reference signal from the oscillation device maintains the same state for a predetermined period. The inspection apparatus in any one of Claims 1-3.   5. When detecting the end point frequency, the oscillation device is set to a setting different from that in actual use, and the time until the oscillation frequency is locked is shortened. The inspection device described in 1.   The inspection according to any one of claims 1 to 5, wherein, when detecting the end point frequency, the oscillation device is set differently from the actual use to narrow the oscillation frequency variable range of each oscillator. apparatus.   7. The inspection apparatus according to claim 6, wherein after detecting an end point frequency by narrowing an oscillation frequency variable region of each oscillator, the oscillation frequency variable region is returned to its original state and lock determination is performed at the end point frequency.   The inspection apparatus according to claim 7, further comprising a control voltage monitor unit that monitors a control voltage for controlling an oscillation frequency of each oscillator and sends the monitoring result to the inspection processing unit. An inspection method for performing pass / fail determination of an oscillation device having a plurality of oscillators each having a different oscillation frequency variable range, the lock determination step for determining whether or not the output of the oscillation device is locked at a desired frequency, and a step of end-point detection for detecting the end point frequency of the variable oscillation frequency range of each oscillator on the basis of the step of the determination result of the lock determining the oscillation frequency variable range of each oscillator on the basis of the detection result of the step of the endpoint detection end And a step of inspection processing for inspecting that they overlap each other. "

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