A programmable logic array includes a dynamic and plane, and an or plane using clocked load devices. The first of this kind of devices was the programmable read only memory. However, the or plane is fixed, limiting the number of terms that can be ored together. In a pla, both the and section and the or section can be programmed. Ecen 248 introduction to digital systems design spring. The pla consists of two programmable planes and and or. Pld as a black box logic gates and programmable switches inputs logic variables outputs logic functions 4. Programmable logic arrays plas are traditional digital electronic devices. A third set of fuses in the output inverters allows th e output function to be inverted if required. Both of these devices are generally categorized into a family of logic devices known as simple programmable logic devices splds. The programmable logic plane is a programmable readonly memory prom. The fundamental components of plas are input buffer, programmable and gate matrix and programmable or gate matrix. The general structure of this device is similar to pla, but in a pal device only and gates are programmable.
Programmable array logic the pal device is a special case of pla which has a programmable and array and a fixed or array. A software programmable logic array spla is disclosed for creating a logic array which can be dynamically programmed to provide any combination of predetermined outputs from any combination of desired inputs. The typical implementation consists of input buffers, the programmable andmatrix followed by the ormatrix, and output buffers. Programmable logic arrays pla programmable logic slide 7 cmos vlsi design programmable logic goal. Pla a programmable logic array pla is a relatively small fpd that contains two levels of logic, an and plane and an or plane, where both levels are programmable. Programmable logic array, abbreviated as pla is a programmable logic device having programmable and gates and or gates. The pal programmable array logic device has a programmable and array and fixed. Programmable logic array programmable logic array allows sumofproducts sop for implementing boolean functions. In particular we describe a general method fpr compactmg a logic array deflned as multiple 101 and column folding and.
Kinoshita 3 department of electrical and computer engineering, university of wisconsinmadison, madison, wi 53706, u. The output of the or plane becomes the input of a restoration plane which is realized by. Programmable logic devices fieldprogrammable gate arrays. The peel array structure is shown in figure with its plalike planes.
Cpld and fpga architectures southern illinois university. Programmable array logic wikipedia republished wiki 2. Us5023775a software programmable logic array utilizing and. This makes pal devices easier to program and less expensive than pla. Each wiredor nanowire is now sandwiched between the array of restoration nanowires in its own plane and the. Programmable logic array pla in a rom, the and section is a decoder that generates all the 2n outputs. In other words, we want a fixed and plane and a programmable or configurable or plane. Programmable diode crosspoints in a crossbar array give us a programmable or plane see marked regions in figure 1.
Programmable logic array pla the pla combines the characteristics of the prom and the pal by providing both a programmable or array and a programmable and array, i. The pla has a set of programmable and gate planes, which link to a set of programmable or gate planes, which can then be conditionally complemented to produce an output. That means each and gate has both normal and complemented inputs of variables. Internally, luts comprise of 1bit memory cells programmable to hold either. Like the pla, it has a wide, programmable and plane for anding inputs together. A single clock having a delay path may be used to control the precharge and decode. This pal architecture had the added benefit of faster tpd and less complex software but without the flexibility of the pla structure. Programmable logic devices part 1 mohammed sharaf sayed mohammed. In the late 1970s the programmable array logic pal architecture was introduced that increased the use of programmable logic. Like memory, gates can be organized into regular arrays. Dec 29, 2015 pld as a black box logic gates and programmable switches inputs logic variables outputs logic functions 4.
This new architecture differs from that of the pla by having one of the programmable planes fixed the or array. A programmable read only memory is a device that includes both the and plane and or plane within a single ic package. Programmable logic devices plds were introduced in the 1970s they are based on a structure with an andor array that makes it easy to implement a sumofproducts expression programmable logic devices ie1204 digital design, ht14 3. Programmable logic 2 inputs and array outputs or product array terms programmable logic arrays plas prefabricated building block of many andor gates actually nor. Programmable logic array pla consists of two planes, the first one is and plane. The or logic lines may then be pulled to a high level during the decode operation. It is most economical to produce an ic in large volumes many designs required only small volumes of ics need an ic that can be. The simulated results of the and plane and or plane can be seen in fig.
It is cheap compared to pla as only the and array is programmable. A pla is a simple programmable logic device spld used to implement combinational logic circuits. The or array in this device is fixed by the manufacturer. Consequently, we cannot effect gating between crossed nanowires and lightly doped independently restore wiredor nanowires in adjacent layers. Programmable array logic a registered trade mark of monolithic memories is a partic ular family o f programmable logic devices plds that is widely used and available from a number of manufacturers.
The op section can be programmed according to our design needs. The spartan 6 pdf has two slices with four luts each. It is generally used to implement combinational logic circuits. Us5023775a software programmable logic array utilizing. A given column of the or array has access to only a subset of the possible product terms pals simpler to understand and use than plas and have performance advantages. Introduction to cpld and fpga design esc306, esc326. The simplest pld device architectures are programmable array logic pal devices and programmable logic array pla devices. By programming the and section, we generate only those boolean product terms that we need. History of programmable logic programmable logic arrays 1970 incorporated in vlsi devices can implement any set of sop logic equations outputs can share common product terms programmable logic devices 1980 mmi programmable array logic pal 16l8 combinational logic.
History of programmable logic programmable logic arrays 1970 incorporated in vlsi devices can implement any set of sop logic equations outputs can share common product terms programmable logic devices 1980 mmi programmable array logic pal 16l8 combinational logic only 8 outputs with 7 programmable pts of 16 input variables. Harding, in rapid system prototyping with fpgas, 2006 2. Logic arrays are mass produced in large quantities, so they are. Better programmable logic element or clb for many years, all fpgas are based around 4luts deemed to be most efficient add block memories add multipliersdsp modules j. Spring 2010 cse370 ix programmable logic 25 pals programmable array logic pal innovation by monolithic memories programmable and array fixed or array faster and smaller or plane no sharing of terms limited number of terms per function. Pla programmable logic arrays submitted by kunalkant on february 16, 2008 8. Chow, architecture of field programmable gate arrays. Design of programmable interconnect for sublithographic. Programmable diode crosspoints between crossed, horizontal and vertical nanowires provided the programmable wiredor planes see fig. Large array of uncommitted andor gates actually nandnor gates you program the array by making or breaking connections. Pal has programmable and array, but fixed or array. Plas are built from an and array followed by an or array, as shown in figure 5. A programmable logic array pla is a kind of programmable logic device used to implement combinational logic circuits.
Clb of spartanii fpgas pdf is comprised of two slices, each with two luts. Pdf programmable logic arrays plas are traditional digital electronic devices. Rom, pal, pla are different optimized implementations of a given circuit using the andor planes. Each output nw in the plane can be programmed to perform the or of its set of inputs. The pal device is a pld with a fixed or array and a programmable and array. Pdf etextiles has received tremendous attention in recent years due to the capability of integrating sensors into a garment to provide high precision. The foregoing is accomplished by providing a first plane of programmable bits for producing a plurality of and terms which are input to a second plane of programmable bits for. The pal architecture consists of two main components.
The software programmable logic array defined by claim 4 further comprising an output polarity select plane means coupled to said or plane means such that said at least one or term output of said or plane means is input to said output polarity select plane means, said output polarity select plane means including a set of programmable bit means. Types and design stylesadvanced technologies general terms design keywords sublithographic architecture, nanowires, programmable logic arrays 1. Programmable logic arrays pla field programmable gate arrays fpga application specific integrated circuits asic full custom designed integrated circuits different from asics. Out of these two arrays and plane is fixed and or plane is programmable. We analyze which qca device quantumdot cell limits the defect tolerance of the andor plane cell of the qcapla by using qca circuit simulator or qcadesigner. Programmable logic array pla programmable logic array is a programmable logical device. Enhancement of defect tolerance in the qcabased programmable. A pla includes a circuit block called an and plane or and array and a circuit block called an or plane or or array. The pal circuits consist of a set of and gates whose inputs can be programmed and whose outputs are connected to an or gate, i. Programmable logic arrays plas implement twolevel combinational logic in.
Nanowirebased sublithographic programmable logic arrays core. Programmable array logic pal in this category of programmable logic devices the and plane is programmable and the or plane is fixed previous example. Produced in large volumes handle many designs required in small volumes a programmable logic part can be. A cost effective design of reversible programmable logic array. Field programmable gate arrays xilinx vertex random logic full custom design regular logic structured design cs 150 fall 2005 lec. Programmable array logic are plds which have planes of and and. The pla has a set of programmable and gate planes, which link to a set of. The inputs in true and complementary form drive an and array, which produces implicants, which in turn are ored together to form the outputs. Quantized evaluation of parameters in proposed rpla implementationin case of reversible logic the important parameters are total logical calculations, no. The programmable logic plane is a programmable readonly memory prom array that allows the signals present on the devices pins or the logical complements of those signals to be routed to an output logic macrocell. Ppt programmable logic array mohammed najm abdullah al. It is also easy to program a pal compared to pla as only and must be programmed. Nanowirebased sublithographic programmable logic arrays.
As only and gates are programmable, the pal device is easier to program but it is not as flexible as the pla. Ecen 248 introduction to digital systems design spring 2008. The programmable logic plane is a programmable readonly memory prom array that allows the signals present on the device pins, or the logical complements of those signals, to be routed to output logic macrocells. Types of logic arrays in real world simplify drawing have different ways of dealing with two logic arrays four basic configurations prom programmable read only memory pal programmable array logic pla programmable logic array pls programmable logic sequencer programmable read only memory prom prom most general. Programmable logic array an overview sciencedirect topics. Pdf a cost effective design of reversible programmable. In the prom the and array will act as a decoder which will decode the address lines. The block diagram of pla is shown in the following figure. Further driven by need of specifically implementing logic circuits, philips invented the field programmable logic array fpla in the 1970s.
Logic gates, counters, arithmetic parts, and storage elements. These devices are basically programmed to implement the boolean functions. Complex programmable logic devices cpld weber state. Programmable logic arrays are important buldlng blocks of vlsi clrcuts aqd systems. Pla a programmable logic array pla is a relatively small fpd that contains two levels of logic, an and plane and an orplane, where both levels are. Journal of technology design of reversible fault tolerant. The current drawn by a pla is input dependent and it. Programmable logic design grzegorz budzy n lecture 1. Programmable logic array pla pla is developed based on the sumofproduct form. We can therefore generate a general purpose array logic with all minterms in its and plane, and capability of using any number of the minterms for any of the array outputs in its or plane. Electrically switchable, diode crosspoints provide a programmable wiredor plane which can be used to con. The high precharge voltage state in the and plane places the logic lines in the or plane in a low voltage state during precharge. Device has a fixed, fully decoded and plane and a programmable or plane. Programmable logic devices plds concordia university.
A cost effective design of reversible programmable logic. Programmable logic array pla use to implement circuits in sop form the connections in the and plane are programmable the connections in the or plane are programmable f1 and plane or plane input buffers inverters and p1 pk fm x1 x2 xn. The effect of logic functionality on area efficiency, ieee journal of. A rom read only memory has a fixed and plane and a programmable or. Programmable array logic pal architecture by fixing one of the programmable planes. The design entry tool for the earlier pal was in the form. This consisted of two planes, a programmable wired and plane and the other as wired or. How can programmable logic arrays plas be built with out relying on lithography. We address the problem of optmizmg the sihcon area and the perfor rnances of large logic arrays. Other basic logic devices, such as multiplexers, exclusive ors, and. The prom implements boolean functions in sumofminterms form. The rom array behaves as an or plane that produces the outputs. Each input has a bufferinverter gate, and each output is.
The pal architecture consisted of a programmable and array and a fixed or array so that each output is the sum of a specific set of product terms. The final programmable logic device to be discussed is the programmable array logic or pal device. The pla has a set of programmable and planes and array, which link to a set of programmable or planes or array, which can then be provisionally complemented to produce an output. Programmable logic array pla is a circuit realization for the twolevel sum of products representation of a multioutput boolean function. Only and plane is programmable, while or plane is fixed fixed. A pla is a simple programmable logic device spld used to.
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