Self-resonant frequency

Once the component values have been calculated, the physical construction of the transformer and the PCB layout become critical for the effectiveness of the filter stage. Magnetic coupling due to stray inductive pick-up of high-frequency noise by the traces and components can circumvent the filter all together. Added to this is the fact that the common-mode filter choke looks more and more capacitive above its self-resonance frequency. The net result is the designer needs to be concerned about the high-frequency behavior of the filter typically above 20 to 40 MHz. 

The si/e of mass within the accelerometer determines the self-resonant frequency of the sensors. The smaller the mass, the higher the frequency Accelerometers are usually operated in a range below this self-resonant, freqncnc)/. 

We should also remember that a capacitor is only a capacitor for frequencies below its internal self-resonant frequency. That is the point where the impedance of its capacitive portion equals its inductive impedance. Since the two impedances always produce opposite V-/phase relationships (180° apart), at the resonant frequency, they effectively cancel out. 

Detecting the scattered light while moving the measuring cell in the direction of the incident light beam permitted the observation of propagating shear waves in the cell outside the electrodes for the crystal samples [36], The phenomenon is illustrated in Fig. 7, where the formation of standing waves upon application of lattice self-resonance frequencies can be observed. 

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. 

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... 

The frequency in which the series resonant circuit changes from capacitive to inductive behavior is called the self-resonance frequency (Equation 9.27). At this frequency, fhe imaginary part of the impedance is zero. Because the... 

Lumped inductors in series connection are usually described by the n model as shown in Figure 9.59. The shunt capacitors depict the parasitic capacitances of coil windings to ground. Capacitive coupling between windings cause the self-resonance frequency /, as shown in Equation 9.38. Because of increasing effective inductance values in the vicinity of a parallel resonance, the inductors can only be used far below the self-resonance frequency (Figure 9.60). 

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