Abstract:
In a method of measuring characteristics of an electronic circuit on a plurality of measurement items by means of a measuring apparatus which operates in accordance with a measurement execution program, a plurality of measurement specifications the measurement items are expressed in the form of a measurement specification description table of a fixed-word-length type. A measurement specification description program is formed in which the measurement specification description table is directly reflected. A measurement execution program is formed by appointing a measuring sequence in the measurement specification description program and by removing redundancy and combining programs of a plurality of measuring items which can be measured in parallel. The measurement execution program is subjected to a debugging conducted by operating the measuring apparatus in accordance with the measurement execution program. The measurement specification description program is amended in accordance with the modification of the measurement execution program effected through the debugging. The characteristics of the electronic circuit are measured by the measuring apparatus in accordance with the measurment execution program after the debugging.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of measuring electrical characteristics of an electronic circuit such as an IC in accordance with a predetermined measuring program. 
     2. Description of the Related Art 
     In general, an electronic circuit after design and construction is subjected to measurement of electrical characteristics conducted by a measuring apparatus. Usually, the measuring apparatus has a plurality of signal generating means and measuring means which are operated in accordance with a predetermined measuring program so as to perform measurement and test of various items. 
     FIG. 2 is a block diagram of a system for measuring electrical characteristics of an electronic circuit by means of such a measuring apparatus. Referring to this Figure, a measuring jig 3 is connected through a cable 2 to the measuring apparatus which is denoted by 1. The measuring jig 3 has an interface circuit 4 for connection to the cable 2, a peripheral circuit 5 and a socket jig 6. An IC as the electronic circuit to be measured is connected to the socket jig 6. The peripheral circuit 5 has a multiplicity of change-over switches (relays) so as to be able to simulate environmental conditions under which the IC 7 is to be used actually and to enable the IC 7 to be tested. 
     The measuring apparatus 1 operates in accordance with a measuring program, so that electrical signals are supplied to the IC 7 through the interface circuit 4 and the peripheral circuit 5. Outputs from the IC 7 are transmitted to the measuring apparatus 1 through the peripheral circuit 5 and the interface circuit 4 so as to be measured by the measuring apparatus 1. Thus, various tests are executed on the IC 7 in accordance with the measuring program. 
     The measuring program for operating the measuring apparatus 1 is formulated by a program language peculiar to the measuring apparatus 1. Hitherto, a process having the following steps has been used for forming the measuring program. 
     Step 1 
     Items of electrical characteristics to be measured on the IC 7 are selected and a measurement specification is worked out on the basis of these items, and a measuring jig 3 for enabling measurement of all these items is designed and fabricated. 
     Step 2 
     The measuring program is formed in accordance with the measurement specification using a programming language peculiar to the measuring apparatus 1. 
     Step 3 
     The measuring jig 3 is connected through the cable 2 to the measuring apparatus 1 and the IC 7 is mounted in the socket jig 6 of the measuring jig 3. The measuring apparatus is operated in accordance with the measuring program to enable a check as to whether desired data are obtainable. When the desired data are failed, the causes of the failure are investigated and the measuring program is modified to eliminate such causes. This operation is repeated until data of all the required items are safely obtained. 
     Measuring program free of error is thus obtained. The measuring program is then improved through the following Steps 4 to 6. 
     Step 4 
     Any duplication or unnecessary program statement is eliminated. 
     Step 5 
     The program is modified to enable parallel or simultaneous measurement of a plurality of measurement items which are measurable under independent measuring conditions and data of which can be handled and processed concurrently or at such high speeds as can be regarded as being materially concurrent. 
     Step 6 
     Measuring sequence are modified and optimized to enable analysis of rejection and to attain improvement in the yield and reduction in the measuring time. 
     Efficiency of the measurement is appreciably improved through Steps 4 to 6. Each of Steps 4 to 6, however, requires that debugging be conducted in the same manner as that in Step 3 described before. 
     The above-described process for forming a measuring program essentially requires high degree of knowledge both in the hardware and the software of the measuring apparatus 1, which in turn necessitates a skilled engineer having a good command of the programming language peculiar to the measuring apparatus 1. In addition, formation and modification of the measuring program are quite time-consuming and require much time and labor. 
     In particular, the operation for changing the measuring sequence conducted in Step 6 is quite complicated and difficult, since this work has to be done taking into account the measuring conditions deleted or rewritten in Steps 4 and 5. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a method of measuring electrical characteristics of an electronic circuit which enables an easy formation of a measuring program having excellent measuring efficiency, thereby overcoming the above-described problems of the prior art. 
     To this end, according to the present invention, there is provided a method of measuring characteristics of an electronic circuit by means of a measuring apparatus which operates in accordance with a measurement execution program, the method comprising: expressing a plurality of measurement specifications corresponding to a plurality of measurement items in the form of a measurement specification description table of a fixed-word-length type; forming a measurement specification description program in which the measurement specification description table is directly reflected; forming a measurement execution program by appointing a measuring sequence in the measurement specification description program and by removing redundancy and combining programs of a plurality of measuring items which can be measured in parallel; debugging the measurement execution program by operating the measuring apparatus in accordance with the measurement execution program; amending the measurement specification description program in accordance with the modification of the measurement execution program affected through the debugging; and measuring the characteristics of the electronic circuit by the measuring apparatus in accordance with the measurement execution program after the debugging. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a flow chart illustrating an embodiment of the method of the invention for measuring characteristics of an electronic circuit; and 
     FIG. 2 is a block diagram of a conventional apparatus for measuring electrical characteristics of an electronic circuit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described hereinafter with reference to the accompanying drawings. 
     Referring to FIG. 1, a measurement specification of an electronic circuit as the measuring object is written by an operator in the form of natural language for each of measurement items in Step 11. In Step 12, the measurement specifications are arranged in the form of Tables of fixed-word-length type, whereby a measurement specification description table is formed. In this Step, the data in the measurement specifications input in Step 11 are allocated in accordance with the contents and sequence suitable for the programming. 
     In Step 13, the measurement specification description table is converted into a measurement specification description program which contains all the control data of the measuring apparatus (not shown) described in the measurement specification description table and, hence, the content of the measurement specification description table is directly reflected in this measurement specification description program. That is, the contents of measurement of the respective measurement items are described in independent and completive forms. Therefore, execution of measurement with this program is possible even when the program of an arbitrary one of the items is taken out or even when the sequence of the measurement items is altered. 
     Step 14 forms a measurement execution program. To this end, the sequence of the measuring items in the measurement specification description program formed in Step 13 is changed in accordance with an externally given sequence changing instruction. In addition, the measurement specification description program with the changed measuring sequence is further processed to eliminate any redundancy such as duplicate of program description or unnecessary program description. At the same time, combination of programs is conducted to enable a parallel or simultaneous processing of a plurality of measurement items which can be processed concurrently or at speeds high enough to be regarded as being processable concurrently. A measurement execution program is formed through these operations. 
     Debugging of the measurement execution program is conducted in Step 15. Namely, the measuring apparatus is actually operated in accordance with the measurement execution program formed in Step 14 to enable check of operation of the measuring apparatus for each of the measurement items. If the desired data cannot be obtained, the measurement execution program is suitably modified in Step 16. This operation is repeated until desired data are obtained for all the measurement items. 
     A measurement execution program for actual use is thus prepared. However, when the measurement execution program formed in Step 15 is modified in Step 16, Step 17 is further executed to amend the measurement specification description program formed in Step 13, in accordance with the content of the modification affected in Step 16. 
     Measurement of characteristics of the electronic circuit is then conducted in Step 18. 
     In Step 19, a question is posed as to whether a change in the measuring sequence is necessary for the purpose of analysis of causes of rejection, improvement in the yield, shortening of measuring time or other requirement. If the answer is YES, the process proceeds to Step 20 in which a process is conducted again for forming a revised measurement execution program. In this process, a revised measurement execution program is formed on the basis of the above-mentioned measurement specification description program amended in accordance with the result of the debugging in Step 15. Any change in the sequence of the measurement items can be conducted very easily because the programs of measurements of the respective measurement items are written in independent and completive form in the measurement specification description program. Thereafter, elimination of duplicate or unnecessary program description and combination of the measuring items which can be measured simultaneously are conducted so that the revised measurement execution program is obtained. The process then returns to Step 15 to enable debugging of the revised measurement execution program. Subsequently, Steps 16 and 17 are executed for amendment of the measurement execution program and amendment of the measurement specification description program, followed by execution of Step 18 in which the measurement is conducted. 
     A practical example of measurement of characteristics of an electronic circuit will be described. It is assumed here that measurement is conducted on six measurement items shown in Tables 1 to 6 on an IC. 
     
                       TABLE 1______________________________________Test item:     Terminal voltage 1 V1Peripheral circuit switch          SW ON 1 3 18 38conditions:Measuring conditions:          Terminal 1 Voltage measured2             12 V    200 mA3              4 V     20 mA4             GNDCriterion value:          [12 V (source voltage)]-[terminal 1          voltage]          5.35 V at minimum          6.55 V at maximum______________________________________ 
    
     
                       TABLE 2______________________________________Test item:    Terminal voltage 5 V5Peripheral circuit switch         SW ON 18 38conditions:Measuring conditions:         Terminal 5 Voltage measured2             12 V    200 mA3              4 V     20 mA4             GNDCriterion value:         2.00 V at minimum 3.00 V at maximum______________________________________ 
    
     
                       TABLE 3______________________________________Test item      Voltage gain 1 GV1Peripheral circuit switch          SW ON 2 4 6 18 38conditions:Measuring conditions:          Terminal A 1 KHz SIN wave volt          measured2             12 V    200 mA3              4 V     20 mA4             GNDCriterion value:          37 dB at minimum 43 dB at maximumCriterion computing          20* log (terminal A output/formula:       input voltage)______________________________________ 
    
     
                       TABLE 4______________________________________Test item:     Voltage gain 2 GV2Peripheral circuit switch          SW ON 2 4 6 18 38conditions:Measuring conditions:          Terminal A 1 KHz SIN wave volt2             10 V    200 mA3              4 V     20 mA4             GNDB Input 1 KHz 2 mVrmsCriterion value:          37 dB at minimum 43 dB at maximumCriterion computing:          20* log (terminal A output voltage/formula:       input voltage)______________________________________ 
    
     
                       TABLE 5______________________________________Test item:      Oscillation frequency 1 FREQ1Peripheral circuit switch           SW ON 2 4 18 38 50 61conditions:Measuring conditions:           Terminal C 2 V.sub.p-p frequency           measured2             12 V    200 mA3              4 V     20 mA4             GNDB Input 10 KHz 10 mVrmsCriterion value:           9.10 KHz at minimum 10.9 KHz at           maximum______________________________________ 
    
     
                       TABLE 6______________________________________Test item:      Oscillation frequency 2 FREQ2Peripheral circuit switch           SW ON 2 4 38 50 61conditions:Measuring conditions:           Terminal C 1 V.sub.p-p frequency           measured2             9 V     200 mA3             4 V      20 mA4             GNDB Input 1 KHz 10 mVrmsCriterion value:           9.10 KHz at minimum 10.9 KHz at           maximum______________________________________ 
    
     Thus, the measurement specification for each measurement item includes the following elements or data which are described in Table of fixed-word length type. 
     1. Item name, 
     2. Peripheral circuit, 
     3. Hardware setting, 
     4. Source, 
     5. Source supply to electrical circuit, 
     6. Measured data format, 
     7. Setting of evaluation criterion, 
     8. Setting of computation, 
     9. Sorting/display of measure result, 
     10. Dismissal of measuring conditions 
     Then, a measurement specification description table as shown in Table 7 is formed with the tables of fixed-word-length type. 
     
                                           TABLE 7__________________________________________________________________________ITEMS                        TERMINAL   TERMINAL    VOLTAGEITEM NAME                    VOLTAGE 1  VOLTAGE 5   GAIN 1ITEM NO. &amp; SYMBOL            1, V1      2, V5       3, GV1__________________________________________________________________________PERIPHERAL CIRCUITSWITCH GROUP 1               1, 3                   2, 4, 6SWITCH GROUP 2               18         18          18SWITCH GROUP 3               38         38          38SWITCH GROUP 4HARDWARE SETTINGSINGLE MODE MEASUREMENT      VM         VM          AVM, APIN CONNECTION               PRV13 = 4 V, 20 mA                                   PRV13 = 4 V, 20                                               PRV13 = 4 V, 20 mA                        P1 = VM    P5 = VM                        P2 = S1    P2 = S1     P2 = S1                        P3 = PRV13 P3 = PRV13  P3 = PRV13                        P4 = GND   P4 = GND    P4 = GND                        S1 = 12 V, 200 mA                                   S1 = 12 V, 200 mA                                               S1 = 12 V, 200 mASETTING OF VOLT MEASURING DEVICE                        DC20 VSETTING OF TIME MEASURING DEVICESETTING OF AUDIO SIGNAL GENERATOR                   1 kHz                                               10 mVrmsSETTING OF AUDIO SIGNAL MEASURING DEVICE            RMS 2 V AC                                               100 mS × 1SOURCE                       ON WAIT = 10 mS                                   ON WAIT = 10 mS                                               ON WAIT = 3 mSSOURCE SUPPLY TO ELECTRONIC CIRCUIT                        ON WAIT = 100 mS                                   ON WAIT = 100 mS                                               ON WAIT = 100 mSMEASURED DATA FORMAT         X.XX V     X.XX V      X.XX dBSETTING OF EVALUATION CRITERION                        5.35 6.35  2.00 3.00   37 43SETTING OF COMPUTATION       12-MEAS                20 logVM/10SORTING/DISPLAY OF MEASURE RESULT                        FBIN = 5   FBIN = 6    FBIN = 7DISMISSAL OF MEASURING CONDITIONS                        ALL CLEAR  ALL CLEAR   ALL__________________________________________________________________________                                               CLEARITEMS                        VOLTAGE    OSCILLATION OSCILLATIONITEM NAME                    GAIN 2     FREQUENCY 1 FREQUENCY 2ITEM NO. &amp; SYMBOL            4, GV2     5, FREQ1    6, FREQ2__________________________________________________________________________PERIPHERAL CIRCUITSWITCH GROUP 1               2, 4, 6    2, 4, 6     2, 4SWITCH GROUP 2               18         18SWITCH GROUP 3               38         38          38SWITCH GROUP 4                          50, 61      50, 61HARDWARE SETTINGSINGLE MODE MEASUREMENT      AVM, A     TIME, C     TIME, CPIN CONNECTION               PRV13 = 4 V, 20 mA                                   PRV13 = 4 V, 20                                               PRV11 = 4 V, 20 mA                        P2 =  S1   P2 = S1     P2 = S1                        P3 = PRV13 P3 = PRV13  P3 = PRV13                        P4 = GND   P4 = GND    P4 = GND                        S1 = 10 V, 200 mA                                   S1 = 12 V, 200 mA                                               S1 = 9 V, 200 mASETTING OF VOLT MEASURING DEVICESETTING OF TIME MEASURING DEVICE                                   FREQ A      FREQ A                                   1 V, +SL100 kHz                                               0 V, +SL10 kHzSETTING OF AUDIO SIGNAL GENERATOR                        1 kHz      10 kHz      1 kHz                        2 mVrms    10 mVrms    10 mVrmsSETTING OF AUDIO SIGNAL MEASURING DEVICE                        RMS 2 V AC                        100 mS × 1SOURCE                       ON WAIT = 3 mS                                   ON WAIT = 3 mS                                               ON WAIT = 3 mSSOURCE SUPPLY TO ELECTRONIC CIRCUIT                        ON WAIT = 100 mS                                   ON WAIT = 100 mS                                               ON WAIT = 100 mSMEASURED DATA FORMAT         X.XX dB    X.XX kH     X.XX kHSETTING OF EVALUATION CRITERION                        37 43      9.10 10.90  9.10 10.90SETTING OF COMPUTATION       20 logVM/2SORTING/DISPLAY OF MEASURE RESULT                        FBIN = 8   FBIN = 9    FBIN = 10DISMISSAL OF MEASURING CONDITIONS                        ALL CLEAR  ALL CLEAR   ALL__________________________________________________________________________                                               CLEAR 
    
     The measurement specification description program is formed by directly converting the measurement specification description table into programming language. The measurement specification description program thus formed, when executed in accordance with the sequence described in the measurement specification description table, is still redundant due to presence of duplication or useless program description. Such redundant portion is therefore removed from the measurement specification description program, whereby a measurement execution program is formed. Table 8 shows the thus formed measurement execution program in the same style as the measurement specification description table shown in Table 7. From a comparison between Tables 7 and 8, it will be seen that the measurement execution program is much simplified as compared with the measurement specification description table in terms of the programming language. 
     
                                           TABLE 8__________________________________________________________________________ITEMS                        TERMINAL   TERMINAL    VOLTAGEITEM NAME                    VOLTAGE 1  VOLTAGE 5   GAIN 1ITEM NO. &amp; SYMBOL            1, V1      2, V5       3, GV1__________________________________________________________________________PERIPHERAL CIRCUITSWITCH GROUP 1               1, 3                   2, 4, 6SWITCH GROUP 2               18SWITCH GROUP 3               38SWITCH GROUP 4HARDWARE SETTINGSINGLE MODE MEASUREMENT      VM                     AVM, APIN CONNECTION               PRV13 = 4 V, 20 mA                        P1 = VM    P5 = VM                        P2 = S1                        P3 = PRV13                        P4 = GND                        S1 = 12 V, 200 mASETTING OF VOLT MEASURING DEVICE                        DC20 VSETTING OF TIME MEASURING DEVICESETTING OF AUDIO SIGNAL GENERATOR                   1 kHz                                               10 mVrmsSETTING OF AUDIO SIGNAL MEASURING DEVICE            RMS 2 V AC                                               100 mS × 1SOURCE                       ON WAIT = 10 mS                                   ON WAIT = 10 mS                                               ON WAIT = 3 mSSOURCE SUPPLY TO ELECTRONIC CIRCUIT                        ON WAIT = 100 mS                                   ON WAIT = 100 mS                                               ON WAIT = 100 mSMEASURED DATA FORMAT         X.XX V                 X.XX dBSETTING OF EVALUATION CRITERION                        5.35 6.35  2.00 3.00   37 43SETTING OF COMPUTATION       12-MEAS                20 logVM/10SORTING/DISPLAY OF MEASURE RESULT                        FBIN = 5   FBIN = 6    FBIN = 7DISMISSAL OF MEASURING CONDITIONS__________________________________________________________________________ITEMS                        VOLTAGE    OSCILLATION OSCILLATIONITEM NAME                    GAIN 2     FREQUENCY 1 FREQUENCY 2ITEM NO. &amp; SYMBOL            4, GV2     5, FREQ1    6, FREQ2__________________________________________________________________________PERIPHERAL CIRCUITSWITCH GROUP 1                          2, 4SWITCH GROUP 2SWITCH GROUP 3SWITCH GROUP 4                          50, 61HARDWARE SETTINGSINGLE MODE MEASUREMENT                 TIME, CPIN CONNECTION                        S1 = 10 V  S1 = 12 V   S1 = 9 VSETTING OF VOLT MEASURING DEVICESETTING OF TIME MEASURING DEVICE                                   FREQ A                                   0 V, +SL100 kHz                                               0 V, +SL10 kHzSETTING OF AUDIO SIGNAL GENERATOR       10 kHz      1 kHz                        2 mVrms    10 mVrmsSETTING OF AUDIO SIGNAL MEASURING DEVICESOURCE                       ON WAIT = 3 mS                                   ON WAIT = 3 mS                                               ON WAIT = 3 mSSOURCE SUPPLY TO ELECTRONIC CIRCUIT                        ON WAIT = 100 mS                                   ON WAIT = 100 mS                                               ON WAIT = 100 mSMEASURED DATA FORMAT                    X.XX kHSETTING OF EVALUATION CRITERION         9.10 10.90SETTING OF COMPUTATION       20 logVM/2SORTING/DISPLAY OF MEASURE RESULT                        FBIN = 8   FBIN = 9    FBIN = 10DISMISSAL OF MEASURING CONDITIONS                   ALL__________________________________________________________________________                                               CLEAR 
    
     The measurement execution program thus obtained may have a plurality of measuring items which can be measured in parallel. The measurement execution program is then modified by combining the measuring programs of such measuring items. The measurement execution program is further modified as desired through debugging. When this modification is conducted, corresponding amendment is conducted on the measurement specification description program. Actual measurement of characteristics of an electronic circuit is then conducted in accordance with this measurement execution program. 
     When a change in the measuring sequence is necessary, a revised measurement execution program is formed on the basis of the measurement specification description program which has been amended in accordance with the result of the debugging. If the revised measurement execution program has to be formed on the basis of the measurement execution program which was actually used in the measurement, quite a complicated operation is necessary because the measurement execution program has been simplified as shown in Table 8 and because reforming by combination of a plurality of measuring item programs for parallel measurement has been conducted on the measurement execution program. In contrast, according to the invention, the revision of the measurement execution program is conducted without difficulty because the measurement specification description program on which the revision is based directly corresponds to the measurement specification description table shown in Table 7. 
     In consequence, the present invention enables a computer or the like system to conduct, without human aid, formation of tables and programs such as the measurement specification description table, measurement specification description program and measurement execution program, as well as revision of the measurement execution program which is conducted as required to meet a demand for a change in the measuring sequence.