Graded quiz 8
Question 1 Mark the true statements.
Any digital circuits can be implemented with Standar Cells or Gate Arrays, but this approach uses to be poorly efficient when the circuit is small, with low performance, or when the required productIon is low. PCB is an acronym of “Printed Circuit Board” The 7400 chip contains 4 2-inputs NAND gates. Such a chip is considered a small scale integration (SSI) circuit.
Question 2 Mark the true statement.
The aim of Microelectronics is the study and implementation of analog and digital circuits within semiconductors materials, most frequently Silicon.
Question 3 Mark the true statements.
Silicon wafers are thin plates of semiconductor material on which the integrated circuits are built. Masks are used to define over which regions of a wafer a particular process will be applied to. Clean Rooms have equipment to ensure that the number of particles suspended in the air is below a certain threshold. This level of cleanness is essential for the production of integrated circuits. Integrated circuits are manufactured in special rooms named “Clean Rooms”. A microelectronic technology is a set of technological processes (such as ion implantation, oxidation, deposition or etching) that can be applied on a semiconductor material (usually silicon) in a particular order to obtain an integrated circuit.
Question 4 Mark the statements concerning Standard Cells which are true.
Macrocells are special library cells that implement, in general, more complex functions than logic gates or bistables. In many cases, libraries contain configurable macrocells such that the designer can define some of their parameters (for instance, number of words and bit/word of a memory block, length of a shift register, etc.). Standard Cells have better performances, in terms of integration density, speed and consumption, than Gate Arrays.
Question 5 Mark the statements concerning Gate Arrays which are true.
Gate Arrays are usually less expensive than Standard Cells because a part of their layout (the part corresponding to the uncommitted cells) is already defined and is identical for all users. This reduces the number of masks needed in the manufacturing process, thus lowering the cost. Gate Arrays are based on the existence of uncommitted cells on the silicon surface that must be customized to form the desired gates or memory elements. There exist computer-aided design (CAD) tools that automatically create the layers required to transform the uncommitted cells of a Gate Array into the desired logic component (gates, memory elements, etc.)
Question 6 Mark the statements concerning FPGAs which are true.
The basic blocks are identical for all the FPGAs. The programming (configuration) of the basic blocks and the interconnection layers in a FPGA is automatically performed by specific computer aided design tools (CAD tolls). Thanks to them, the designer works with a component library (logic gates, memory elements, etc.) and doesn’t have to worry about the dumping of his/her circuit into the FPGA (“technology mapping”). FPGAs consist of a set of basic blocks and interconnections layers that can be customized. FPGAs are particularly suitable for the implementation of prototypes and small series.
Digital Systems: From Logic Gates to Processors