Reversible logic circuit

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. 

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. 

In Figure 5-la is shown a schematic representation of a silicon MOSFET (metal-oxide-semiconductor field effect transistor). The MOSFET is the basic component of silicon-CMOS (complimentary metal-oxide-semiconductor) circuits which, in turn, form the basis for logic circuits, such as those used in the CPU (central processing unit) of a modern personal computer [5]. It can be seen that the MOSFET is isolated from adjacent devices by a reverse-biased junction (p -channel stop) and a thick oxide layer. The gate, source and drain contact are electrically isolated from each other by a thin insulating oxide. A similar scheme is used for the isolation of the collector from both the base and the emitter in bipolar transistor devices [6],... 

The problem is the reverse process, how to extract them and put in some logical sense, called models or theories. Modem digital technology has made it possible to manipulate multidimensional signals with systems that range from simple digital circuits to advanced parallel computers. When talking about sets of visual information, the process of their quantification for further analysis or observation can be set as follows ... 

This makes clear that any two electrical terminals, also if one is grounded and not represented as such, form a port. However, in many treatments of electrical circuits the logical order is reversed First, a distinction is made between potential and potential differences. Next a relation between the potential differences and the potentials is derived via the incidence matrix and only then it is recognized that one of the rows (balance equations) refers to a reference node (ground) which should be omitted from the incidence matrix to obtain the so-called reduced incidence matrix. This culture may have led Willems to drawing this conclusion. 

Fig. 10 (A) Polarization curves of the biofuel cell with the pH-switchable 02-cathode obtained at different pH values generated in situ by the enzyme logic network (a) pH ca. 6, (b) pH ca. 4, (c) pH ca. 6. Inset The reversible changes of the open-circuit voltage produced by the cell at the variable pH. (B) Electrical power density generated by the biofuel cell on different load resistances at different pH values generated in situ by the enzyme logic network (a) pH ca. 6, (b) pH ca. 4, (c) pH ca. 6. Inset The reversible changes of the maximum power density produced by the biofuel cell at the variable pH, (C) The maximum power density produced by the biofuel cell as the function of different combinations of the input signals. (Adapted from ref. 76 with permission).

Equation 21.20 is known as the rectifier equation because of the fact that a large current can flow if V is positive (p-side made positive or forward biased), but only a small current results as V is made negative (reverse biased) as shown in Figure 21.7. Circuit elements that utilize p-n junctions are known as diodes. They find use as rectifiers, blocking devices for preventing unwanted reverse current flow, and even as logic devices. 

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