Impedance transformation

Such sensors utilizing solid-state electronics have significant advantages. The actual sensing area is very small. Hence, a single miniaturized solid-state chip could contain multiple gates and be used to sense several ions simultaneously. Other advantages include the in-situ impedance transformation and the ability for temperature and noise compensation. While the concept of the ISFET is very... 

The all important characteristic of a A./4 line is that it acts as an impedance transformer with the transformation given... 

For AC systems the calculation of the short-circuit current is more complicated, particularly when generators and motors are both present in the system. The simplest calculations occur when the source of voltage can be assumed to be of constant magnitude during the fault duration. In AC systems the source impedance will be the addition of the cable impedance, busbar impedance, transformer internal impedance, the appropriate internal impedance of the generator, the appropriate internal impedance of the motors in system and the impedance of the overhead transmission lines. 

The MMW electrical properties of the cavity and the oscillator at resonance are effectively fixed in their manufacture. This treatment addresses the coupling between those two circuit elements to achieve optimal performance. It considers only the circuits at resonance that is, under the working condition of the spectrometer. Recall that the capacitive and inductive reactances in a tuned circuit at resonance cancel each other yielding a purely resistive circuit element. Nonetheless the reactances both still remain and are manifest in the property Q. The treatment will yield the reflection coefficient p of the coupling interface between the cavity and oscillator in terms of their gs and the mutual inductance coupling coefficient M of the impedance transformer that the interface represents. Optimum performance will be when the two circuit elements are critically coupled to each other and that will be shown to occur when p = 0. 

Transmission Line Sections Discontinuities Impedance Transformers Terminations Attenuators Microwave Resonators Tuning Elements Hybrid Circuits and Directional Couplers Filters Ferrite Components Passive Semiconductor Devices... 

Impedance transformers are used to interface two sections of line with different characteristicimpedances. The smoothest transition and the one with the broadest bandwidth is a tapered line as shown in Fig. 4.22(a) and Fig. 4.22 (e). This element tends to be very long and so step terminations called quarter-wave impedance transformers (see Fig. 4.23(h) and Fig. 4.23(i)) are sometimes used although their bandwidth is relatively small centered on the frequency at which I = A. /4. Ideally, Zq,2 = /Zq Zo,. ... 

FIGURE 4.23 Discontinuities. Waveguide discontinuities (a) capacitive E-plane discontinuity, (b) inductive H-plane discontinuity, (c) symmetrical inductive H-plane discontinuity, (d) inductive circular iris discontinuity, (e) resonant window discontinuity, (f) capacitive post discontinuity, (g) diode post mount, and (h) quarter-wave impedance transformer. Microstrip discontinuities (i) quarter-wave impedance transformer, (j) open microstrip stub, (k) step, (1) notch, (m) gap, (n) crossover, (o) bend. 

Theory of Distributed-Parameter Circuits and the Impedance Transforming into a modal domain. 

Option for impedance transformation very near the high-ohmic electrode with input impedance > 10 12, guarded signal and capacitance neutralization for physiological measurements. 

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