Body capacitance

Incidentally, Schottky diodes do not have any reverse recovery current issues, but they do have some body capacitance, which can produce similar effects. However, that fear has always proven to be exaggerated. I have personally not seen any application having a performance issue explicitly related to a bad Schottky. The only exception was a case where the leakage current of the Schottky was so high, it was prematurely tripping the current comparators inside the switcher IC. And there was also a reliability issue once, concerning the dV/df rating of a commercial Schottky. Both these issues are discussed elsewhere in this book. 

We have already noted above that in analyzing excitable systems one has, more often than not, to deal with a parabolic equation with a nonlinear source. In this section we will concern ourselves with an excitable medium of a different type, where the signals are transmitted in the neuron network not by the local currents but by the nervous impulses traveling along the axons. The propagation speed of the activity wave will, if this transmission mode is possible at all, depend not only on the signal transmission speed but also on the other characteristics of nerve cells such as cell body capacitance, conductance, etc. 

Here, C is neuron body capacitance, (p is the potential measured on the neuron body, t is time, ij is total synaptic current of a given neuron, and g is passive conductance of the neuron membrane or leakage conductance (for simplicity the leakage e.m.f. is taken as equal to the resting potential). Assuming the net to be two-dimensional and considering the steady-state excitation mode in it, we have that the variables

self-similar coordinate ... 

Aliau-Bonet and Pallas-Areny (2012, 2013) have studied the effect of body capacitance to ground in four-electrode bioimpedance measurements and found that stray capacitance between the measured body and ground could lead to inductive artifacts and resonance behavior. 

Aliau-Bonet, C., Rallas-Areny, R., 2012. On the effect of body capacitance to ground in tetrapolar bioimpedance measurements. IEEE Trans. Biomed. Eng. 59, 3405—3411. 

FIGURE 17.27 Illustration of body capacitive line coupling. 

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