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Digital Logic Families
Published in Jerry C. Whitaker, Microelectronics, 2018
Programmable array logic (PAL) was first introduced by Monolithic Memories, Inc. In their simplest form, PALs consist of a large array of logic AND gates fed by both the true (uninverted) and complemented (inverted) senses of the input signals. Any AND gate may be fed by either sense of any input. The outputs of the AND gates are hardwired to OR gates that drive the PAL outputs (see Fig. 7.15). By programming the AND inputs, the PAL user can implement any logic function provided that the number of product terms does not exceed the fanin to the OR gate. Modern PALs incorporate several logic macrocells that include a programmable inverter following the AND/OR combinatorial logic, along with a programmable flip-flop that can be used when registered outputs are needed. Additional AND gates are used to clock and reset the flip-flop. Macrocells usually also have a programmable three-state buffer driving the block output and programmable switches that can be used to feed macrocell outputs back into the AND–OR array to develop combinatorial logic with many product terms or to implement state machines.
Digital Design with Programmable Logic Devices
Published in Suman Lata Tripathi, Sobhit Saxena, Sushanta Kumar Mohapatra, Advanced VLSI Design and Testability Issues, 2020
M. Panigrahy, S. Jena, R. L. Pradhan
In general, a CPLD may be viewed to have a number of logic blocks, a dedicated I/O block and a switch matrix interconnecting them. I/O block consists of I/O elements that provide buffering for the input and output signals. The logic block is formed by several logic elements known as macrocells. A macrocell comprises AND and OR arrays, a dedicated flip-flop, and control signals for implementation of the desired combinatorial or sequential functions. Fast routing between macrocells leads to lower time delays within a logic block. Dedicated global clock lines leverage proper clock distribution among logic blocks and uniform timing properties. The modern CPLDs contain 32–1700 macrocells enabling designers to implement complex logic functions.
Architect’s role to improve in-building wireless coverage
Published in Cogent Engineering, 2020
Mohammad Tanvir Kawser, Zebun Nasreen Ahmed
This section briefly discusses the RF technologies that can be used to provide in-building wireless connectivity and architects need to be conversant with these technologies in order to engage in the relevant issue. The platform for wireless connectivity in buildings can have three classes as described below. Outside Base Station: The cellular communication system has an inbuilt spatial connotation that splits the geographical area into a number of cells, and each cell is served by a base station. A cell is referred to as macrocell or microcell if the cell size is large or medium, respectively. A building can be pervaded by signal from a cellular base station, located outside the building.