Application Notes > Control Signal and Vector Insertion for Q-Star Test Modules

Application Notes:
Control Signal and Vector Insertion for Q-Star Test Modules

SYNOPSIS
This Application Note describes how to use VTRAN to automatically insert control signals and control vectors into WGL or STIL files which have been generated specifically for IDDQ current testing. The modifications to the vectors made by VTRAN provide support for Q-Star Test's family of advanced, high-speed IDDQ/ISSQ test and measurement modules. These Ixxx modules have the unique characteristic of being virtually transparent to the device under test and to the automatic test equipment (ATE). The specific Q-Star module types currently supported are the QD-10xx product family in general and the QD-1011, QD-1011HC24 and QD-1011HCLite more specifically.

These products are typically placed on the interface board (loadboard, probe card, dut board, ...) that connects the device under test with the ATE system. Q-Star has developed it's products so that they are test system independent and can be used on any test platform. The concept of the modules is that for the ATE system they look like part of the DUT and for the DUT they look like they are part of the ATE. The only penalty for this is that required control and communication has to be embedded in the test program, and this is place where VTRAN fits in. Using VTRAN's ability to automatically insert control signals and vectors into the ATPG vectors, the Q-Star Ixxx test modules become very easy to use and it becomes very easy to exploit  their full capabilities, making high-speed and high accuracy current measurements very accessible.

OVERVIEW
A number of automatic test program generation (ATPG) products today provide options for generating a set of vector data that will setup the device for a current measurement, usually IDDQ. Based upon simulations and empirical data, these measurements can provide a very good indicator as to whether or not the device is functioning correctly. A fast, highly accurate current measuring device can thus greatly improve the average test time as well as the reliability for complex ICs.

Within the WGL or STIL files that are generated for IDDQ testing, there are normally markers located at points in the vector sequences where the current test should take place. For WGL files, this marker is usually an annotation which is something like { measureIDDQ }. In the STIL syntax there is a specific statement available for this: IddqTestPoint; . In order to activate and control the Q-Star IDDQ test module, VTRAN makes the following modifications to the WGL or STIL vectors:

• Add 3 signals to the vector data which are used to communicate with the test
  module. Two of the signals are inputs; MD is a data input, CLK is a communication synchronization input. The third signal, DOUT, is an output. VTRAN adds these 3 signals to the WGL/STIL file, plus sets default timing for them, during the read process.
• Insert some optional initialization vectors at the beginning of the pattern
  set. The measurement modules have default settings, but if test conditions or
  protocols are desired that are different than the defaults, then these
  initialization vectors need be inserted. Typically, these vectors would be
  used to configure the module for operating mode, sample setting and global
  reference setting when appropriate.
• At each location in the pattern file where an IDDQ marker is found, VTRAN
  will insert the appropriate vector sequence depending the options selected by
  the user.
• At the end of the pattern vectors, VTRAN will insert some vectors to read
  out stored measurement data from the module if the appropriate option is set
  by the user.

For all vectors that are inserted by VTRAN, only the 3 added signals are used.
For all other signals, the outputs are set to X (don't care), non-clock
inputs maintain their last state, and clock signals are disabled.

INSERTING CONTROL SIGNALS AND VECTORS
The insertion of control signals and vectors by VTRAN happens during the
reading of the WGL or STIL files by the respective canned reader. It is
therefore independent of the target output format. This means that the
insertions can be performed during translations from WGL/STIL to any of the
test (ATE) formats VTRAN supports, or back to another WGL or STIL file.
Instructing VTRAN to perform the Q-Star flow insertions is accomplished using
a Q-Star statement block that is added to the OVF_BLOCK of the VTRAN command
file. This Q-Star statement block has the following syntax and parameter
options ([ ] means optional parameter):

Q-Star
Product = "QD1011 | QD1011HC24 | QD1011HCLite",
[Keyword = "IDDQ_keyword",] { default is measureIDDQ }
[Comtest = "Y | N",]
[SF = "Y | N"],
[Mode = "1 | 2",]
[Sample = "1 | 4 | 16 | 256 | 1024",]
[GRef = "N|S|D, value_1, [value_2]",]
[VRef = "N|Y, [vec#, value_1 [,vec#, value_2]]",]
[NoM = "N|Y, value",]
[Readout = "N|A|S, [SV|DV,] [1,2,...N]",]
[MemRead = "N|Y, [value]"]
;

These parameters have the following meanings:

Product: Used to identify the Q-Star IDDQ test module type being used
Keyword: Used when the input file is WGL to indicate the annotation
   text string which identifies the IDDQ test points in the vector data.
   The default for this is "measureIDDQ".
ComTest : is used to specify whether or not a communication test is to be
   done at the start of the test program.
SF: is used to specify whether or not a special function is to be executed
   at the start of the test program
Mode: is used to specify the desired measurement operating mode (1 or 2))
Sample: is used to specify the number of samples taken on which a
   measurement result will be based
GRef: is used to specify if global pass/fail references will be used
VRef: is used to specify if vector specific reference values are to be used
   and prior to which measurement the vector specific reference value specified
   is to be inserted (pass/fail references set remain valid till a new value is
   shifted into the module)
NoM: is valid when the module supports pre/post stress delta-IDDQ and is
   used to specify the number of pre and post stress measurements
Readout: If the first parameter associated with Readout is “N” or “A” then
   no other parameters must be specified. The range specifier “-“ is not
   allowed when specifying the readout points, only a enumerated list
   is supported.
MemRead: is used to specify how many values need to be read back
   from the module at the end of the pattern data.

For each of the specific Products (test module types), the combination of
valid parameters will depend on the specific test and protocol objectives.
Refer to the literature and technical assistance provided by Q-Star Test
( www.QStar.be ) for detailed information on these.

THE OVF_BLOCK OF VTRAN COMMAND FILE
Included in the VTRAN software bundles that are available from our web site is
a QStar directory which contains information on the vectors to be inserted as
a result of the different parameters. In order to tell VTRAN to perform the
insertions, a Q-Star statement block is inserted in the OVF_BLOCK which
specifies the various parameter values for the desired current testing. When
using this Q-Star insertion flow, the WGL and STIL readers should be invoked
as follows ([ ] indicates optional):

tabular_format wgl -cycle -scan -keep_annotations
    [-include_cells] [-expand_reps] ;
or
tabular_format stil -cycle -scan [-keep_annotations]
    [include_cells] [-expand_reps] ;

For both readers, the -include_cells flag is only necessary if the output
format is either WGL or STIL also (i.e. going from WGL/STIL -> WGL/STIL).
For ATE test pattern output, this flag should not be used. The vectors that
get inserted by VTRAN into the Q-Star Test flow typically contain a large
number of repeat vectors which by default will become repeat vectors in the
target output file also. If this is not desirable, or if the target test
system does not support repeat vectors, then the -expand_reps flag can be used to tell VTRAN to expand the repeats into multiple single vectors. Following are some
examples of command file OVF_BLOCKs:

EXMAPLE 1:

OVF_BLOCK
  begin
  orig_file = "Design1.wgl";
  tabular_format WGL -cycle -scan -keep_annotations -include_cells ;
  Q-Star
    Product = "QD1011",
    Keyword = "measIDDQ",
    ComTest = "Y",
    Sample = "1",
    GRef = "D 0.4mA 0.8mA",
    Mode = "1"
    ;
  end

EXAMPLE 2:

OVF_BLOCK
  begin
  orig_file = "Design2.stil";
  tabular_format STIL -cycle -scan -keep_annotations ;
  Q-Star
    Product = "QD1011HC24",
    ComTest = "Y",  Sample = "4",
    GRef = "D 9A 18A",
    Mode = "2",
    MemRead = "Y 5"
    ;
  end

THE PROC_BLOCK and TVF_BLOCK
The only part of a VTRAN command file which is affected by the Q-Star control
insertion is the OVF_BLOCK as described above. The PROC_BLOCK and
TVF_BLOCK of the command file will remain exactly the same as they would be if
the insertions were not taking place. For information on the contents of
these blocks in the command file, refer to the other Application Notes for WGL
or STIL translations.  For example translations using this flow, also see the INTERFACES directory bundle (INTERFACES/QSTAR) available on the Source III web site at: www.sourceiii.com/vtran_download_software.html .