Abstract:
In the testing device of a semiconductor integrated circuit, each of the logics is provided with the JTAG circuit includes: a boundary scan register that executes a test of the logic in accordance with a test data input and stores a test result, a data register, a pseudo bypass register having a bypassing function of the test data input, a first selector connected to the data register and the pseudo bypass register, which selectively takes out outputs of the registers, a bypass register having the bypassing function of the test data input, an instruction register for giving an operation command, and a second selector connected to the boundary scan register, the first selector, the bypass register, and the instruction register, which is selectively controlled by the instruction register. In this construction, the output from the second selector of a specific logic is connected to the input of another logic.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a testing device of a semiconductor integrated circuit that specifically includes more than one different logics, such as a memory core, and incorporates a JTAG circuit (circuit conforming to the Joint Test Action Group standard), and a method of testing the same.  
           [0003]    2. Background Art  
           [0004]    [0004]FIG. 9 is a block diagram illustrating the conventional testing device of a semiconductor integrated circuit that incorporates the JTAG circuit. The semiconductor integrated circuit mounted on the same chip includes two different logics (logic  1  and logic  2 ), and the logics each include the JTAG circuits each.  
           [0005]    In the figure, reference numeral  11  is integrated into the logic  1 , and denotes a Boundary Scan Register (hereunder, referred to as BSR) that composes a major part of the JTAG circuit, which has an equivalent function to the conventional test probe, and stores the test result of the logic  1 . Reference numeral  12  denotes a Data Register (hereunder, referred to as DR) in the JTAG circuit, and reference numeral  13  a Bypass Register (hereunder, referred to as BR), which bypasses the test data input to the output, thus forming the shortest route.  
           [0006]    Reference numeral  14  denotes an Instruction Register (hereunder, referred to as IR), which reads and decodes the command bits from the well-known TAP (Test Access Port) controller not illustrated.  
           [0007]    Reference numeral  15  denotes a selector connected to the foregoing registers each, which is selected and controlled by the IR  14  to send out either one of the register outputs. Reference numeral  21  denotes a BSR integrated into the logic  2 ,  22  a DR,  23  a BR,  24  an IR, and  25  a selector, and any of them has the same configuration as that of the logic  1 .  
           [0008]    Here, TDI signifies a test data input signal to the JTAG circuit, and TDO a test data output signal from the JTAG circuit, and the output from the selector  15  of the logic  1  is the input signal to the logic  2 .  
           [0009]    The operation of testing each of the logics twice and reading the test results in this configuration will be described with reference to a flow chart shown in FIG. 10.  
           [0010]    First, in Step S 1  the test mode of the logic  1  is set. Next, in Step S 2  the first test of the logic  1  is executed, and in Step S 3  the test result in the BSR  11  is stored. Then, in Step S 4  the test result of the first test stored in the BSR  11  is read out. This readout signal is inputted to the logic  2  by way of the selector  15 , and outputted to the test data output TDO by way of the BR  23  and the selector  25  of the logic  2 . Here, the selector  15  of the logic  1  is set to select the test result of the BSR  11  by the IR  14 ; and in the logic  2 , the selector  25  is set to select the BR  23  by the IR  24 .  
           [0011]    And then, in Step S 5  the second test of the logic  1  is executed, and in Step S 6  the test result in the BSR  11  is stored.  
           [0012]    In Step S 7 , the test result of the second test is read, and in the same manner as the first test, the test result signal from the BSR  11  is outputted to the TDO of the logic  2 .  
           [0013]    Next, in Step S 8  the test mode of the logic  2  is set, and in Step S 9 , the first test of the logic  2  is carried out. In Step S 10  the test result in the BSR  21  is stored, and in Step S 11 , the test result is read out.  
           [0014]    The readout signal is outputted from the BSR  21  to the TDO by way of the selector  25 .  
           [0015]    Also in this case, the selector  25  is set to select the test result of the BSR  21  by the IR  24 . And then, in Step S 12  the second test of the logic  2  is carried out, and in Step  13  the test result in the BSR  21  is stored.  
           [0016]    Next, in Step S 14  the test result of the BSR  21  is read out. The readout signal is outputted to the TDO by way of the selector  25 , in the same manner as the first test, and the test is completed in Step S 15 .  
           [0017]    The conventional in-circuit test of a semiconductor integrated circuit by the JTAG circuit is carried out as above. And, in case of the two logics  1 ,  2  as the testing objects being simultaneously in the test, when the test result is read from the BSR  11  in one logic, for example, in the logic  1 , the BR  23  in the logic  2  is made to function. However, the BR  23  or BR  13  is made to be valid, when the IR  24  or IR  14  of the JTAG circuit is all “1”. Therefore, the logic that set the BR  23  or BR  13  has to slip out of the test mode (for example, RUNBIST) set by the IR  24  or IR  14 , whereby the simultaneous testing of the logics accompanied with plural times readouts of the test results becomes impossible, which is disadvantageous.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention has been made in view of the above circumstances, and an object of the invention is to provide a testing device and a test method that attains the bypassing function being not influenced by the state of the Instruction Register.  
           [0019]    According to one aspect of the present invention, there is provided a testing device of a semiconductor integrated circuit having more than one different logics and JTAG circuits built in, which executes an in-circuit test of the logics. The JTAG circuit includes a boundary scan register that executes a test of the logic in accordance with a test data input and stores a test result; a data register; a pseudo bypass register having a bypassing function of the test data input; a first selector connected to the data register and the pseudo bypass register, which selectively takes out outputs of the registers; a bypass register having a bypassing function of the test data input; an instruction register for giving an operation command; and a second selector that is connected to the boundary scan register, the first selector, the bypass register, and the instruction register, which is selectively controlled by the instruction register. The JTAG circuits are provided to each of the logics, and the output from the second selector of a specific logic is an input of another logic.  
           [0020]    According to another aspect of the present invention, there is provided a testing device of a semiconductor integrated circuit having more than one different logics and JTAG circuits built in, which executes an in-circuit test of the logics. Each of the logics is provided with: a control block including a boundary scan register that executes a test of the logic in accordance with a test data input and stores a test result, a data register, a pseudo bypass register having a bypassing function of the test data input, and a first selector connected to each of the registers, which selectively takes out outputs of the registers; and a bypass register; an instruction register; and a second selector that is connected to these registers and the first selector, which is selectively controlled by the instruction register. The output from the second selector of a specific logic is an input of another logic.  
           [0021]    According to another aspect of the present invention, there is provided a testing device of a semiconductor integrated circuit having more than one different logics and JTAG circuits built in, which executes an in-circuit test of the logics. Each of the logics is provided with: a control block including a boundary scan register that executes a test of the logic in accordance with a test data input and stores a test result, a data register, a pseudo bypass register having a bypassing function of the test data input, and a first selector connected to each of the registers, which selectively takes out outputs of the registers; a bypass register and an instruction register that are common to each of the control blocks; and a second selector connected to the each control block, the bypass register and the instruction register, which is selectively controlled by the instruction register. The output from the first selector of a specific control block is an input of another control block.  
           [0022]    According to another aspect of the present invention, there is provided a test method of a semiconductor integrated circuit, which carries out an in-circuit test thereof by a testing device thereof described above.  
           [0023]    The testing device and test method of a semiconductor integrated circuit relating to the invention provides each of the logics with the JTAG circuit including: the BSR that executes a test of the logic in accordance with a test data input and stores a test result, the DR, the TR having a bypassing function of the test data input, the first selector connected to the DR and TR, which selectively takes out the outputs of the registers, a BR having a bypassing function of the test data input, the IR for giving an operation command, and the second selector that is connected to the BSR, the first selector, the BR, and the IR, which is selectively controlled by the IR, in which the output from the second selector of a specific logic is connected to the input of another logic, whereby, the bypassing function can be implemented which is not influenced by the state of the IR.  
           [0024]    Further, it is possible to carry out the test without setting the test mode repeatedly after using the bypassing function, thus leading to simplification of the test flow and accordingly a simultaneous testing of plural logics accompanied with plural times readouts of the test results becomes possible, and whereby the time for testing can be shortened.  
           [0025]    Also, the testing device and test method of a semiconductor integrated circuit relating to the invention includes a selector on the input of the TR, whereby the test data input to be bypassed and arbitrary information can be inputted selectively. Information unique to the logic, for example, a pass or fail signal of the memory core can be added, and the information unique to the memory core can be read out at the same time of reading the output from the BSR.  
           [0026]    Further, to configure the TR with plural bits will attain N-fold information.  
           [0027]    Further, in the testing device and test method of a semiconductor integrated circuit relating to the invention, each of the logics is provided with: a control block including the BSR that executes a test of the logic in accordance with a test data input and stores a test result, the DR, the TR having a bypassing function of the test data input, and the first selector connected to each of the registers, which selectively takes out outputs of the registers; the BR; the IR that are common to each of the control blocks; and the second selector connected to each control block, the BR and IR, which is selectively controlled by the IR, in which the output from the first selector of a specific control block is the input of another control block, whereby the JTAG circuit is configured. Thus, one JTAG circuit will be able to carry out a simultaneous testing of plural logics.  
           [0028]    Other and further objects, features and advantages of the invention will appear more fully from the following description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a block diagram of the first embodiment.  
         [0030]    [0030]FIG. 2 is a flow chart of the first embodiment.  
         [0031]    [0031]FIG. 3 is a block diagram illustrating the configuration of the TR and that constitute the major part of the second embodiment, and the signal paths to these components.  
         [0032]    [0032]FIGS. 4A to  4 F are waveforms in correspondence with the mode transition of the TAP controller to illustrate the third embodiment.  
         [0033]    [0033]FIG. 5 is a block diagram illustrating the configuration of the TR that constitute the major part of the third embodiment, and the signal paths to these components.  
         [0034]    [0034]FIGS. 6A to  6 H are waveforms in correspondence with the mode transition of the TAP controller to illustrate the third embodiment.  
         [0035]    [0035]FIG. 7 is a block diagram to illustrate the configuration of the fourth embodiment.  
         [0036]    [0036]FIG. 8 is a block diagram to illustrate the configuration of the fourth embodiment.  
         [0037]    [0037]FIG. 9 is a block diagram illustrating the conventional testing device of a semiconductor integrated circuit that incorporates the JTAG circuit.  
         [0038]    [0038]FIG. 10 is a flow chart of the related art. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    First Embodiment  
         [0040]    The first embodiment of the invention will now be described with reference to the drawings.  
         [0041]    [0041]FIG. 1 is a block diagram of the first embodiment, in which the same or the equivalent parts to FIG. 9 are given the same symbols to omit the explanations. The difference from FIG. 9 lies in that the first embodiment includes Transfer Registers in replacement of the BR  13  and  23 , and the DR  12  and  22  controls the TR  16  and  26 . In FIG. 1, 16 signifies a transfer register (TR) that constitutes the JTAG circuit of the logic  1 , which assumes the same configuration as the BR  13 , and has the function to bypass the test data input signal TD 1  to the output.  
         [0042]    Reference numeral  17  signifies a first selector that is connected to the TR  16  and the DR  12 , which is selectively controlled and selected by the DR  12 .  
         [0043]    Also,  18  signifies a second selector that is connected to the BSR  11 , the output terminal of the first selector  17 , the BR  13 , and the IR  14 , which is, in the same manner as in FIG. 9, selectively controlled by the IR  14 , and the output of the second selector is the input signal to the logic  2 .  
         [0044]    Further,  26  signifies the TR,  27  a first selector,  28  a second selector incorporated into the logic  2 ; and these are configured in the same manner as those in the logic  1 , and the output of the second selector  28  is the test data output signal TDO.  
         [0045]    With this configuration, the operation of testing each of the logics twice and reading the test result will be described with reference to the flow chart shown in FIG. 2.  
         [0046]    First, in Step S 21  the test modes of the logic  1  and the logic  2  are set. Next, in Step S 22  the first tests of the logic  1  and the logic  2  are executed, and in Step S 23  each test results are stored into the BSR  11  and the BSR  21 . Then, in Step S 24  the first test result in the logic  1  is read out, which is stored in the BSR  11 . This readout signal is inputted to the logic  2  by way of the second selector  18  that is selecting the BSR  11 , according to the IR  14 .  
         [0047]    In the logic  2 , the DR  22  makes the first selector  27  select the TR  26 , and the IR  24  makes the second selector  28  select the output from the first selector  27 . Therefore, the test result signal from the logic  1  is outputted to the test data output TDO by way of the TR  26 , the first selector  27 , and the second selector  28  of the logic  2 .  
         [0048]    And then, in Step S 25  the first test result of the logic  2  is read, which is stored in the BSR  21 . At this moment, since the second selector  28  is selecting the BSR  21  according to the IR  24  in the logic  2 , the readout signal is outputted to the test data output TDO by way of the second selector  28 .  
         [0049]    Thereafter, in Step S 26  the second tests of the logic  1  and the logic  2  are carried out, and in Step S 27  each test results are stored into the BSR  11  and the BSR  21 . Then, in Step S 28  the second test result of the logic  1  is read out, and the test result signal from the BSR  11  is outputted to the TDO of the logic  2  by way of the same route as that of the first test.  
         [0050]    Also, in Step S 29  the second test result of the logic  2  is read out, and the test result signal from the BSR  21  is outputted to the TDO by way of the same route as that of the first test, and in Step S 30  the test is completed.  
         [0051]    Thus, in this embodiment, since the DR  12  and  22  controls to select the TR  16  and  26 , respectively, it is possible to achieve the bypassing function that is not influenced by the state of the IR  14 , or the IR  24 .  
         [0052]    Further, in the conventional testing device as shown in FIG. 9, since the IR  14  and  24  selectively controls the BR  13  and  23 , at the reading of the test result of the logic  1 , when carrying out the test of the logic  2  after bringing the BR  23  of the logic  2  into function, it has been necessary to set the test mode repeatedly, as shown in the Step S 8  in FIG. 10. However, since this embodiment utilizes the bypassing function of the TR  16  and  26 , the logic  2  will not slip out of the test mode, thus leading to simplification of the test flow.  
         [0053]    Therefore, as shown in the flow chart in FIG. 2, a simultaneous testing of plural logics accompanied with plural times readouts of the test results becomes possible, and the time for testing can be shortened.  
         [0054]    Second Embodiment  
         [0055]    Now, the second embodiment of the invention will be explained with reference to the drawings.  
         [0056]    [0056]FIG. 3 is a block diagram illustrating the configuration of the TR  16  and  26  that constitute the major part of the second embodiment, and the signal paths to these components.  
         [0057]    In FIG. 3, 16,  26  denote the TR  16  of the logic  1 , and the TR  26  of the logic  2 , respectively. Reference numeral  30  denotes the third selector provided on the input of the TR  16  or the TR  26 , and a Pass-Data being one input of the third selector  30  is directly connected to the test data input TDI in FIG. 1, to which the test data to be bypassed is inputted. An IN-Data being the other input is an input terminal to receive arbitrary information in each of the logics, such as, a pass or fail signal of the memory core. These input are selectively controlled and selected by a SHIFT DR signal of the TAP controller not illustrated. That is, the information unique to each of the logics can be added to the TR  16  and  26  by way of the IN-Data.  
         [0058]    [0058]FIG. 4 illustrates waveforms in correspondence with the mode transition of the TAP controller. As shown in FIG. 4B, the input of the SHIFT-DR signal makes the third selector  30  in FIG. 3 select the IN-Data; accordingly, the information of the IN-Data as shown in FIG. 4E appears at the TDO as shown in FIG. 4F, which can be read out together with the Pass-Data being the test data input.  
         [0059]    Third Embodiment  
         [0060]    Next, the third embodiment of the invention will be described with reference to the drawings.  
         [0061]    [0061]FIG. 5 is a block diagram illustrating the configuration of the TR  16  and  26  that constitute the major part of the third embodiment, and the signal paths to these components.  
         [0062]    Here, in FIG. 5, the symbols of the TR are illustrated in correspondence with the logic  1  as an example. That is, in FIG. 5,  16 ( 1 ),  16 ( 2 ), . . .  16 (N) each denote the TR of plural bits, and  30 ( 1 ),  30 ( 2 ), . . .  30 (N) denote the third selectors provided on the inputs of the TR  16 ( 1 ), TR  16 ( 2 ), . . . TR  16 (N). The functions and input signals of the selectors, and so forth are equivalent to those of the third selector  30  in the second embodiment.  
         [0063]    [0063]FIG. 6 illustrates, in the same manner as FIG. 4, waveforms in correspondence with the mode transition of the TAP controller, and plural arbitrary information as shown in FIG. 6E through FIG. 6G are prepared as the IN-Data. As shown in FIG. 6B, the input of the SHIFT-DR signal makes the third selectors  30 ( 1 ),  30 ( 2 ), . . .  30 (N) of each bit in FIG. 5 sequentially select the IN-Data; accordingly, the information of the IN-Data as shown in FIG. 6E through FIG. 6G appear sequentially at the TDO as shown in FIG. 6H, which can be read out together with the Pass-Data being the test data input.  
         [0064]    This embodiment is designed to be able to add arbitrary information inherent to each of the logics by each bit as mentioned above, and it is accordingly possible to attain N-fold information, as compared to the second embodiment.  
         [0065]    Fourth Embodiment  
         [0066]    Next, the fourth embodiment of the invention will be described with reference to the drawings.  
         [0067]    [0067]FIG. 7 and FIG. 8 illustrate the configuration of the fourth embodiment. In these figures, the same or the equivalent parts to FIG. 1 are given the same symbols to omit the explanations.  
         [0068]    In FIG. 7, B 1  signifies a first control block of logic  1  including the BSR  11 , TR  16 , DR  12 , and a first selector  37  that is connected to these registers and controlled by the DR  12 . Reference numeral  38  signifies a second selector that is connected to the first selector  37 , BR  13 , and IR  14 , and is selectively controlled by the IR  14 . B 2  signifies a second control block of logic  2  including the BSR  21 , TR  26 , DR  22 , and a first selector  47  that is connected to these registers and controlled by the DR  22 . Reference numeral  48  signifies a second selector that is connected to the first selector  47 , BR  23 , and IR  24 , and is selectively controlled by the IR  24 .  
         [0069]    This embodiment provides the logic  1 , logic  2  with the control blocks B 1  and B 2 , respectively, to thereby separate the JTAG circuit from the logics. This configuration realizes a circuit configuration, for example, as shown in FIG. 8. In this FIG. 8, JC is a JTAG circuit that includes a control block B, a BSR  33 , an IR  34 , and a selector  58  that is connected to these and controlled by the IR  34 . Further, the control block B includes, as the arrow shows the detailed construction, the control block B 1  corresponding to the logic  1  and the control block B 2  corresponding to the logic  2 .  
         [0070]    Thus, the BR  33  and the IR  34  and the selector  58  function as the common components to both the blocks B 1 , B 2 .  
         [0071]    With this configuration, one JTAG circuit will implement a simultaneous testing of plural logics.  
         [0072]    Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may by practiced otherwise than as specifically described.  
         [0073]    The entire disclosure of a Japanese Patent Application No. 2001-224899, filed on Jul. 25, 2001 including specification, claims, drawings and summary, on which the Convention priority of the present application is based, are incorporated herein by reference in its entirety.