Capacitative coupling

Figure C2.13.3. Schematic illustrations of various electric discharges (a) DC-glow discharge, R denotes a resistor (b) capacitively coupled RF discharge, MN denotes a matching network (c), (d) inductively coupled RF discharge, MN denotes matching network (e) dielectric barrier discharge.

But as the harmonics do exist in the system, they do affect an inductive load. They may also disturb a communications network as a result of capacitive coupling, whose effects are magnified in the presence of capacitor units in the power system. It is therefore considered relevant to discuss this subject in more detail to make the harmonic study more informative. 

Tliis is the prime cause of noise and distortion in an audio system. The capacitive coupling (conduction) between the power and the communication lines gives rise to such an effect. It is associated more with the voltage of the system and particularly when it is capacitor compensated. Even without the power capacitors, the leakage (coupling) capacitances between the HV or EHV power lines, particularly 132 kV and above, and the overhead communication lines play an important role and give rise to this phenomenon. Systems lower than 132 kV do not cause such a situation as a result of the insignificant capacitive effect. 

Figure 3-62 A good method for enhancing the heatsinking capabilities of a PCB island and minimizing capacitive coupling to other PCB traces.

The components connected between the emitter-follower and the currentsensing filter capacitor can be thought of as a resistor divider. An additional 0.17 V needs to appear at pin 7 (through a 1K resistor) so the amount of current that must be contributed to that node is 0.17 V/1K which is 170 pA. The capacitive coupling of the PNP to pin 7 essentially centers the oscillator waveform upon the current ramp. So,... 

Dielectric constant/loss The value of the dielectric constant is important in the wire because of the effect that it has in coupling currents in one set of wires into another set of wires. The higher the dielectric constant, the higher the value capacitor that is formed between two wires. The capacitor thus formed is a signal carrying device at the frequencies used in communications and a signal can be capacitively coupled from one circuit to another. PE is the preferred choice for insulation of communication wire because of its low dielectric constant that minimizes the intercircuit coupling effect usually referred to as cross-talk. 

MHz was capacitively coupled to the substrate susceptor to control the ions energy in the plasma. 

In the measurements, one commonly determines the impedance of the entire ceU, not that of an individual (working) electrode. The cell impedance (Fig. 12.13) is the series combination of impedances of the working electrode (Z g), auxiliary electrode (Z g), and electrolyte (Z ), practically equal to the electrolyte s resistance (R). Moreover, between parallel electrodes a capacitive coupling develops that represents an impedance Z parallel to the other impedance elements. The experimental conditions are selected so that Z Z g Z g. To this end the surface area of the auxiliary electrode should be much larger than that of the working electrode, and these electrodes should be sufficiently far apart. Then the measured cell impedance... 

As a switching device capable for ultra-large-scale integrated circuits (ULSIs) comprises only one Coulomb island with two leads (electrodes) and a capacitively coupled gate electrode attached to it. This system works as a simple on/off switch and it is often called the SE transistor. Applying a voltage to the outer electrodes of this circuit may either cause sequential transfer of electrons onto and out of the central island or to have no charge transport, i.e. the transistor remains in non-conductive state. The result... 

Figure 2. Scanning electron micrograph of a SE transistor with source and drain ( + U/2 and —U/2, respectively) feeding the central island (Insel), which is capacitively coupled to a gate electrode. The size of the central island is about 60 nm x 60 nm.

FIG. 4. Schematic representation (a) of a parallel-plate, capacitively coupled RF-discharge reactor, with unequal-size electrodes. The potential distribution (b) shows the positive plasma potential Vp and the negative dc self-bias voltage... 

A further assumption is that the time-averaged current is zero, because of the capacitive coupling of the power supply to the electrodes. With this model unequal-size electrode systems can be modeled, by using an area ratio a = Ag/Ap. The ratio between Vdc and Vrf has been calculated for 1 < a < 10, and is in excellent agreement [174, 175] with experimental data [176, 177]. 

The plasma potential is about 25 V (Figure 63a). This value of the plasma potential is typical for the silane plasmas in the asymmetric capacitively coupled RF reactors as used in the ASTER deposition system, and is also commonly found in argon or hydrogen plasmas [170, 280, 327]. From the considerable decrease of the dc self-bias with increasing frequency (Figure 63a) it is inferred that the... 

In contrast, Heintze and Zedlitz [236] also presented data on the plasma potential as function of frequency in silane plasmas the plasma potential varies from about 27 V at 35 MHz to about 20 V at 180 MHz. Moreover, Dutta et al. [284] used a symmetric capacitively coupled RF reactor and estimated the plasma potential in their system from the applied voltage at the powered electrode. A decrease of the plasma potential from 45 V at 13.56 MHz to only 15 V at 70 MHz is observed. This difference in behavior is thought to be solely due to the different reactor geometries. 

Dielectric losses arise from the direct capacitive coupling of the coil and the sample. Areas of high dielectric loss are associated with the presence of axial electric fields, which exist half way along the length of the solenoid, for example. Dielectric losses can be modeled by the circuit given in Figure 2.5.3. The other major noise source arises from the coil itself, in the form of an equivalent series resistance, Rcoii. Exact calculations of noise in solenoidal coils at high frequencies and small diameters are complex, and involve considerations of the proximity and skin depth effects [23],... 

Fig. 1. Sketch of a capacitively coupled glow discharge deposition system (Knights et al., 1978).

Wagner, 1982 Beyer and (capacitively coupled) glow discharge 4.4 280-300 UT2 1.29 6 x 10 3 Evolution... 

Exposure of bulk GaAs Si wafers to a capacitively coupled rf deuterium plasma at different temperatures generates deuterium diffusion profiles as shown in Fig. 1. These profiles are close to a complementary error function (erfc) profile. At 240°C, the effective diffusion coefficient is 3 x 10 12 cm2/s. The temperature dependence of the hydrogen diffusion coefficient is given by (Jalil et al., 1990) ... 

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