Inductor parameters

From Fig. 10.13, we see the latter condition is fulfilled in the first three cases, but not in the fourth case. The most stable situation is obtained with Rx. The choice R = RcosL is however usually adopted when the power supplied to the resistor must be measured. The control of temperature in the real (dynamic) case is much more complex. The problem is similar to that encountered in electronic or mechanical systems. The advantage in the cryogenic case is the absence of thermal inductors . Nevertheless, the heat capacities and heat resistances often show a steep dependence on temperature (i.e. 1 /T3 of Kapitza resistance) which makes the temperature control quite difficult. Moreover, some parameters vary from run to run for example, the cooling power of a dilution refrigerator depends on the residual pressure in the vacuum enclosure, on the quantity and ratio of 3He/4He mixture, etc. 

Tnom - the nominal temperature, 27°C Note that if an inductor model is not specified, all model parameters are set at their default values and the value in the simulation is the value specified in the schematic. 

Functional fibres, filaments and yams are the basic building blocks of electrotextiles. The textile industry has demonstrated a remarkable capability to incorporate both natural and man-made filaments into yarns and fabrics to satisfy a wide range of physical parameters which survive the manufacturing process and are tailored to specific application environments. Electronic components can be fabricated within and/or on the surface of filaments and can subsequently be processed into functional yams and woven into fabrics. Passive components such as resistors, capacitors and inductors can be fabricated in several different manners. Diodes and transistors can be made on long, thin, flat strands of silicon or formed in a coaxial way. Progress has been made in the development of fibre batteries and fibre-based solar cells. In addition, a variety of actuated materials (piezoelectric, etc.) can be made into multiple long strands (filaments) and subsequently be woven into fabric. 

As compared to a parallel combination of a resistor and capacitor, the CPE is able to provide a much better fit to most impedamce data. The CPE can achieve this fit using only three parameters, which is only one parameter more than a typical RC couple. Some investigators allow a to take values from —1 to 1, thus treating the CPE as an extremely flexible fitting element. For a = 1, the CPE behaves as a capacitor for a = 0, the CPE behaves as a resistor and for a = —1 the CPE behaves eis an inductor (see Section 4.1.1). 

In Figure 2-2 we first introduced the most basic, yet far-reaching design parameter of the power supply itself — its current ripple ratio r. This is a geometrical ratio that compares and connects the ac value of the inductor current to its associated dc value. So... 

Having validated our choice of inductor, we can look a little more closely at the important issue of how the wide-input range impacts the other key parameters and stresses in our proposed converter. This also helps in correctly selecting the other power components. 

Question 22 What are the key parameters of an off-the-shelf inductor that we need to consider ... 

The transmission line model is composed of discrete resistors, inductors, capacitors and conductance. A length I of transmission line can conceptually be divided into an infinite number of increments of length Al dl) such that per-unit-length resistance R, inductance L, conductance G, and capacitance C are given. Each of the parameters R, L, and G is frequency-dependent. For example, R and L will change in value due to skin effect and proximity effect. G will change in value due to frequency-dependent dielectric loss [25]-[27]. From literature [24] we can get these four parameters ... 

The main geometrical parameters of a coplanar spiral inductor are the strip width (W), the spacing between adjacent turns (S), the internal radius (Rmt), the number of turns (Nt), the spacing to the surrounding coplanar ground plane (Sg), and the metal thickness (VetaO- A relevant frequency-dependent parameter to measure the overall electrical quality of an inductor is the Q factor obtained when one port is shorted the higher the Q factor is, the better the device electrically behaves. The second parameter, often measured to evaluate inductors, is the self-resonance frequency. A selfresonance occurs when the inductive reactance of the device is equal to the parasitic capacitive reactance between the inductor and the substrate, i.e., if Q = 0. 

The next step in designing an LP prototype filter network is to select inductors and capacitors so that the admittance parameters 21 and 722 are as specified in Table 4.10. The procedure is demonstrated for a representative fourth-order filter (Chebyshev with 3-dB ripple), and the results are given in Table 4.11 for... 

Frequency scaling A procedure for changing the cutoff frequency, peaking frequency, or other special frequency of a filter without changing either the filter s topology or types of network elements used. Values of capacitors and inductors are divided by parameter b where 1 < h < infinity if the filter is being scaled up in frequency. Resistors are not changed in value. 

Magnitude scaling A procedure for changing the values of network elements in a filter section without affecting the voltage ratio or current ratio transfer function of the section. Resistors and inductors are multiplied by parameter a, while capacitors are divided by a. If 1 < a < infinity, then the magnitudes of the impedances are increased. 

After the inductor L1 has been selected and the operating parameters have been decided, in accordance with Eq. (10.74) and Eq. (10.76), the next design is the selection of capacitor Cl. 

The switching transformer for the flyback regulator is in reality two inductors linked together by a common magnetic core. Therefore, in selecting the transformer, the dominating parameters are the primary and secondary inductances. 

Coil designs are usually not optimized for line width and, subsequently, smallest outline, because their quality factor is influenced by the line width, adversely. On the other hand, wide lines cause high parasitic capacitances, thus, reducing the self-resonance frequency. In particular, the crossing conductor has a major impact. The lowest stray capacitance is achieved by a high wire-bond loop (Figure 9.27). Countless design combinations are available for each inductor. It has to be decided which coil parameter, besides the... 

Ideal inductors act as a pure reactance directly proportional to the frequency (Equation 9.32). They cause a current-voltage shift of 90° in an electrical circuit. The inductance value is influenced by design and material parameters as described earlier. 

The simple inductor model is valid up to the first resonance only. Second-order effects are not considered in this description. Figure 9.61 shows measured and simulated S-parameters of a three-dimensional LTCC inductor. If effects above the first resonance need to be included, a more sophisticated model needs to be established. 

The quality factor is frequency dependent and is applicable to lumped coils only (Figure 9.62). Inductors that are not small compared to the signal wavelength reveal line transformation effects. The resulting quality factor derived from measured S-parameters appears to be negative. 

S-parameters of an inductor with (a) lumped, (b) distributed behavior (both inductors have the same inductance value of 9.6 nH). 

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