Embedding a portion of the distributed capacitance
within the substrate for general decoupling results in reductions of both board size and the number of on-board components.
First, we calculate the distributed capacitance
C of the line by looking it at as a capacitor.
This additional distributed capacitance
loads the via barrels, thereby decreasing the differential impedance and increasing the effective dielectric constant.
At each step along the way, the signal is asking, "What is the ratio of the voltage to the current?" The voltage is the signal it is applying and the current is the current it sends into the signal conductor and back to the return conductor, each step of the way, to charge up each successive section of the distributed capacitance
of the line.
With this configuration, the distributed capacitance
can be accessed by dropping a single via (low inductance) down to the power plane.
The helical resonator is tuned via the distributed capacitance
of the tuning screw at the high electric field point of the resonator.
Besides, to obtain the sufficient [C.sub.diel], which serves as the distributed capacitance
, a dielectric substrate with high relative permittivity is also an important factor.
3,519,959, the concept of embedded distributed capacitance
(closely-spaced power and ground planes for power supply &coupling) was disclosed.
Co is the intrinsic capacitance of the trace and Cd is the distributed capacitance
of the receivers, both per unit length.
Capacitors can be conventional discrete or, a whole capacitance sheet may be used as distributed capacitance
. Distributed capacitance
is the storage of energy between the power and ground layers by employing a dielectric.
On Monday we will cover all of the current advanced design technologies, including HDI, microvias, embedded passives, fine-pitch BGAs and routing, channel routing, very large BGAs (<600 pins), signal integrity, distributed capacitance
and new design tools.
(While Sanmina-SCI is not a material manufacturer or supplier, it presented on the merits of its distributed capacitance
materials.) The material technologies covered were planar or distributed capacitance
, thin-film resistors and discrete ceramic thick-film (CTF) capacitors.