TA的每日心情  开心 20191012 08:19 

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1.DesignCon20061There is an ongoing interest in refining the simulation models for passive components in electronic
circuits. For simple analyses, bypass capacitors are modeled by a series CRL equivalent network. To
capture the frequency dependency of the circuit parameters, more complex equivalent circuits can be
used: ladder LR networks to model the frequency dependent inductance and resistance and/or CR
networks to model the frequency dependent capacitance. These equivalent circuits have the advantage
of being compatible with both timedomain and frequency domain SPICE simulations, but the optimum
topology of the equivalent circuit may depend on the type and construction of capacitor. This paper first
summarizes the current distributions inside MLCC parts simulated with a bedspring model and we make
some counterintuitive observations about the frequency dependency of inductance and resistance in tall
MLCC parts. Based on those observations we then derive a slowwave causal model, which represents
the capacitor with a periodically loaded lossy transmission line. It is shown that the load circuit in the
unit cell corresponds to the waveguide formed by two adjacent capacitor plates. The unit cells are
further simplified and lumped together into one lossy, openended transmission line with a series RL
circuit capturing the impedance of the cover layer of the capacitor. The parameters of the single lossy
transmission line are derived from the geometry and material properties. It is shown that the counterintuitive
features in the model are captured by a virtual capacitance and dielectric loss tangent, which
combine the dielectric loss of the ceramic and the resistive losses of the capacitor plates. The model is
shown to capture the important characteristics of measured data, and it is simple enough to be used in
multiple copies in circuit simulators.
2.DesignCon20062
SlowWave Causal Model for Multi Layer Ceramic Capacitors
3.DesignCon20063
Beyond the traditional components of conductive and dielectric losses, periodic discontinuities
generate additional losses on interconnects. For instance, on printedcircuit boards (PCBs) and
packages, periodic discontinuities may come from perforated planes and loading from regularly
arranged via fields under large packages and sockets. There is an increased slope of attenuation
with frequency due to periodic losses, with deeper resonant dips at frequencies where the
periodic structure constructively lines up reflections. The frequencies where the dips occur are
lower if the propagation delay between subsequent discontinuities is longer. The depth of the
dips depends on how severe the discontinuities are. The paper provides measured and simulated
data of this extra loss mechanism, together with simulated studies examining the impact of
several geometrical parameters.
4.DesignCon20064
ATTENUATION IN PCB TRACES DUE TO PERIODIC DISCONTINUITES
5.DesignCon20065
Power Distribution Network (PDN) design of highspeed and highpower systems appears to be black
magic: there are contradictory design philosophies, component selection and layout rules. Suboptimum
or not proper power distribution increases the supplyrail noise, but this impacts system performance in
a statistical manner, convoluted with many other variables. For this reason, over a wide range, different
PDN designs may appear to perform equally well, giving rise to several misconceptions. This paper
compares some of the popular boardlevel PDN design methods by their impedance profiles and worstcase
transient noise. It is shown that smooth RL type selfimpedance profiles result in the lowest
transient noise. Component placement is also analyzed, and it is concluded that bypasscapacitor
location matters mostly in PDNs, where the impedance of the power/ground planes does not match the
target impedance. Finally, measured impedance profiles are shown for some of the popular SUN
servers, illustrating some of the possible PDN design philosophies.
6.DesignCon20066
This paper gives an overview of thin laminate applications at SUN’s Scalable Systems Groups, Horizontal
Systems (formerly Volume Server Products) business unit. The paper summarizes some of the
experimental engineering tests with various thin laminates on test boards and production boards, and gives
a brief overview of the application of 1mil laminates in a recent product.

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