This is called static timing analysis because it does

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This is called static timing analysis because it does not require the creation of a set of test (or stimulus) vectors (an enormous job for a large ASIC). Timing analysis works best with synchronous systems whose maximum operating frequency is determined by the longest path delay between successive flip-flops. The path with the longest delay is the critical path .
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Logic simulation or gate-level simulation can also be used to check the timing performance of an ASIC. In a gate-level simulator a logic gate or logic cell (NAND, NOR, and so on) is treated as a black box modeled by a function whose variables are the input signals. The function may also model the delay through the logic cell. Setting all the delays to unit value is the equivalent of functional simulation. If the timing simulation provided by a black-box model of a logic gate is not accurate enough, the next, more detailed, level of simulation is switch-level simulation which models transistors as switches—on or off.
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Switch-level simulation can provide more accurate timing predictions than gate-level simulation, but without the ability to use logic-cell delays as parameters of the models. The most accurate, but also the most complex and time-consuming, form of simulation is transistor-level simulation . A transistor-level simulator requires models of transistors, describing their nonlinear voltage and current characteristics. Each type of simulation normally uses a different software tool. A mixed-mode simulator permits different parts of an ASIC simulation to use different simulation modes.
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Boundary-Scan Test It is possible to test ICs in dual-in-line packages (DIPs ) with 0.1 inch (2.5 mm) lead spacing on low-density boards using a bed-of-nails tester with probes that contact test points underneath the board. Mechanical testing becomes difficult with board trace widths and separations below 0.1 mm or 100 mm, package-pin separations of 0.3 mm or less, packages with 200 or more pins, surface- mount packages on both sides of the board, and multilayer boards
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Boundary-scan test ( BST ) is a method for testing boards using a four-wire interface (five wires with an optional master reset signal). A good analogy would be the RS-232 interface for PCs. The BST standard interface was designed to test boards, but it is also useful to test ASICs. The BST interface provides a standard means of communicating with test circuits on-board an ASIC. We do need to include extra circuits on an ASIC in order to use BST. This is an example of increasing the cost and complexity (as well as potentially reducing the performance) of an ASIC to reduce the cost of testing the ASIC and the system.
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boundary scan. (a) Boundary scan is intended to check for shorts or opens between ICs mounted on a board. (b) Shorts and opens may also occur inside the IC package. (c) The boundary-scan architecture is a long chain of shift registers allowing data to be sent over all the connections between the ICs on a board.
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Fig (a) illustrates failures that may occur on a PCB due to shorts or opens in the copper traces on the board.
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  • Fall '15
  • prasad
  • Logic, Electronic design automation, Logic Synthesis, ASIC

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