Logical circuit

Cryoelectronics. Operation of CMOS devices at lower temperatures offers several advantages and some disadvantages (53). Operation at Hquid nitrogen temperatures (77 K) has been shown to double the performance of CMOS logic circuits (54). In part, this is the result of the increase in electron and hole mobilities with lower temperatures. The mobiHty decreases at high fields as carrier speeds approach saturation. Velocity saturation is more important for cryoelectronics because saturation velocities increase by only 25% at 77 K but saturation occurs at much lower fields. Although speedup can... 

The purpose of the various electromechanical elements of a circuit is to effect monitoring, safety and automatic control, and these may he connected separately into a custom-huilt system. The availahility of electronic logic circuits gives the possibility of integrated systems and superior control, using a large number of input signals. Observed parameters are ... 

Recalling Bennett s and Fredkin s trick to erase the garbage bits, the way in which the reversible logic circuit in figure 6.9 can be made to act as a real reversible serial-adder circuit is to first operate the circuit as shown, store the desired output, and then operate it backwards using the output and all intermediary garbage bits as new input. After all operations are completed in the reverse direction, we will be left with our desired answer stored on the side and with the serial-adder circuit back in its original state ready for another run. 

In summary then, any computation that can be carried out by a conventional circuit can be reproduced by a conservative logic circuit (assuming only that some... 

When used together, the three gates NOT, CONTROLLED NOT and CONTROLLED CONTROLLED NOT constitute a universal reversible set, and can thus be used to construct an arbitrary logical circuit. 

The invention of the germanium transistor in 1947 [I, 2] marked the birth of modem microelectronics, a revolution that has profoundly influenced our current way of life. This early device was actually a bipolar transistor, a structure that is mainly used nowadays in amplifiers. However, logical circuits, and particularly microprocessors, preferentially use field-effect transistors (FETs), the concept of which was first proposed by Lilicnficld in 1930 [3], but was not used as a practical application until 1960 [4]. In a FET, the current flowing between two electrodes is controlled by the voltage applied to a third electrode. This operating mode recalls that of the vacuum triode, which was the building block of earlier radio and TV sets, and of the first electronic computers. 

FET is ihe on-off current ratio, which indicates its ability to shut down the current, and is particularly relevant in applications such as active matrix displays and logical circuits. Because of the presence of p-n junctions at both the source and drain electrode, the on-off ratio of MOSFETs is in the I0y range [12J, while that of a-Si H TFT is limited to 106 [13], High mobility ensures high on-current and, hence, also contributes to a high on-off ratio. 

The Keyes figure of merit, based on thermal conductivity as an additional factor, (see following section) predicts the suitability of a semiconductor for dense logic circuit applications. Again, diamond is far superior to other materials. 

Keyes figure of merit (dense logic circuits) 1 0.5 6 32... 

In petrochemical and bulk commodity chemical manufacture, real-time process control has been a fact of life for many years. There is considerable understanding of processes and control of process parameters is usually maintained within tight specifications to ensure statistical process control to within six sigma, or the occurrence of one defect in a million. This has been enabled through the use of real-time analytical capability that works with programmable logic circuits to make small changes to various process inputs and physical parameters as required. 

Structural Model for Logic Circuits at the Molecular Level... 

Intramolecular Logic Circuits with Only One Node. 242... 

Bachtold, A. Hadley, P. Nakanishi,T. Dekker, C. 2001. Logic circuits with carbon nanotube transistors. Science 294 1317-1320. 

See also CMOS image sensors bipolar transistors with, 22 249 improving performance of, 22 257 logic circuits with, 22 251-253 Moore s law and device scaling and,... 

Field effect transistors (FETs), 19 155 22 144, 162-166. See also Transistors characteristics of, 22 164-166 in CMOS logic circuits, 22 251-253 compound semiconductors in, 22 160, 161-162... 

Logarithmic-mean driving force, packed column absorbers, 1 53 Logarithmic mean temperature difference (LMTD), 13 251, 252 Logic circuits, CMOS, 22 251-253 Logic gates, molecular-based, 17 61 Log-mean temperature difference (LMTD), 26 64... 

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