Circuit elements

In addition to the obvious effect of high dielectric constant glasses on the capacitance of the circuit elements iato which they enter, their dielectric strengths maybe more important. Siace the amount of energy a capacitor can store varies as the first power of the dielectric constant and the second power of the voltage, a glass with twice the dielectric strength is as effective as one with four times the dielectric constant. 

The frequency response or switching speed of the bipolar transistor is governed by the same processes which control the speed of thep—n junction, the capacitance associated with the movement of charge into and out of the depletion regions. To achieve high frequencies the dimensions of the active areas and parasitic circuit elements must be reduced. The two critical dimensions are the width of the emitter contact and the base thickness, W. The cutoff frequency,, is the frequency at which = 57 / - b /t > where is the emitter-to-coUector delay time and is the sum of the emitter... 

Even the tight controls in siUcon integrated circuit manufacturing are not yet sufficient to produce absolutely identical sensors on a single wafer. Cahbration of the final product is usually necessary, often by adjusting the value of a circuit element on the IC such as a resistor. The caUbration process can be automated, but it stiU adds to the cost of batch-fabricated sensors. Clever means of self-caUbration, particularly in field use, are constantiy being sought. 

Because a length of metal associated with the connector contact is ordinarily in the path between the contact end to which a wire is terminated and the contact interface, its resistance (bulk resistance) must be added to contact resistance when considering the connector as a circuit element. This overall resistance is sometimes erroneously called contact resistance. 

In maldug electrochemical impedance measurements, one vec tor is examined, using the others as the frame of reference. The voltage vector is divided by the current vec tor, as in Ohm s law. Electrochemical impedance measures the impedance of an electrochemical system and then mathematically models the response using simple circuit elements such as resistors, capacitors, and inductors. In some cases, the circuit elements are used to yield information about the kinetics of the corrosion process. 

Electrical Units 278. Electrical Circuit Elements 281. Transient and AC Circuits 284. AC Power 285. Magnetism 286. Transformers 288. Rotating Machines 289. Polyphase Circuits 293. Power Transmission and Distribution Systems 294. 

The simplest circuit element is the short circuit. Figure 2-66a illustrates the concept of a short circuit. A source of emf (labeled v ) produces a current that flows relatively unimpeded through the conductor resulting in a nearly zero potential drop and an infinite current. 

Circuit elements may be connected in either a series or parallel configuration. In the series configuration, the same current flows through each and every element, and the circuit potential drop (or emf that is developed by the voltage source) is the algebraic sum of the potential drops of each individual element. For sources in series, the total emf developed is the algebraic sum of the emfs developed by each individual source. 

In the parallel configuration, the same potential difference occurs across each and every element with the total current being the algebraic sum of the current flowing through each individual circuit element. Table 2-35 summarizes the equivalent resistance, conductance, capacitance, and inductance of series-parallel configurations of resistors, capacitors, and inductors. 

When multiple circuit elements are involved, the resultant phase angle difference between the current and the potential will result from the contribution of each element. 

Reactive circuit elements (e.g., capacitors and inductors) store, not dissipate, energy. While the energy stored is periodically returned to the rest of the circuit, reactive elements do require increased potential or current to flow in the circuit. The power that must be supplied for the reactive elements is termed reactive power, and it is calculated as... 

Strictly, the strain gauges referred to above come into this category, since in such cases the change in the measured quantity causes a corresponding change in the resistance of the element. However, the principle has a much wider application, using changes in either the inductive or capacitive reactance of electrical circuit elements. 

To mitigate the problem, a diffusion barrier is incorporated between the aluminum and the silicon (see Sec. 5 below). It is also possible to replace aluminum by alloys of aluminum and copper or aluminum and silicon, which have less tendency to electromigration. These alloys are usually deposited by bias sputtering. However, they offer only a temporary solution as electromigration will still occur as greater densities of circuit elements are introduced. It was recently determined that improvements in the deposition of aluminum by MOCVD at low temperature with a dimethyl aluminum hydride precursor may reduce the problem.bl... 

A small fire in a computer room, a telephone exchange, or an assembly plant for communication satellites can cause enormous damage because of minute amounts of corrosion on circuit elements. Furthermore, if either water or a halogenated agent is used to control the... 

An integrated circuit (IC) is a monolithic assembly of electrically isolated circuit elements. What this means is that each circuit element is formed on top of, or beneath, other circuit elements to form a compact assembly. Each conductive layer is separated by a non-conducting layer, usually composed of an oxide such as silicon dioxide, Si02- The assembly includes... 

Etching to define the features of individual circuit elements... 

Cleaning to prevent contamination and the consequent introduction of defects into circuit elements by peirticulate matter. 

Circuit elements at optical frequencies nanoinductors, nanocapacitors, and nanoresistors. Physical Review Letters, 95, 095504. 

Different approaches have been discussed up to now how to reach this size scale and consequently how to bridge the size gap between the conventionally fabricated circuit elements of some ten nanometers in size and at least the true atomic or molecular scale. In that concern noble metal nanoclusters have attracted much attention. 

As in electrodeposition, proper mask design aimed at achieving as uniform a layout of circuit elements as possible will be one of the keys to the future success of electroless deposition in microelectronics, whether it is employed to deposit conductors (Cu) or thin barrier layers. 

Tool design will have to be carried out keeping in mind the need to control transport of any additives and dissolved O2 to patterned circuit elements, particularly those not surrounded by other actively plating features. 

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