The Filter for Interference Suppression
in Power Circuits of Digital
Patent of Russia
Low efficiency of
filtering schemes recommended by manufacturers of processors stems from
low internal resistance of a processor as a source of interference in
power distribution circuits.
presented invention (the multi-section filter) is designed to be applied
to PC motherboards, to power circuits of PCI, PCI-E and AGP expansion
cards and memory modules, and immediately to audio and video cards. As
opposed to currently used engineering solutions recommended by
manufacturers of processors, the invention is based on selective
suppression of interferences generated by devices listed above with
multi-section low-pass filters, which leads to the following benefits:
1. Applying “The filter for interference suppression in power circuits
of digital chips” (hereafter, The Filter) to processors and controllers
of a PC main board allows:
Lowering the cost of a main board by using cheap oxide condensers in
power filters and by excluding reel parts (such as inductance chokes
with ferrite iron) or replacing them with ferrite absorbing tubes. This
allows cutting the expenses of assembling as well.
Lowering the cost of a design process by simplifying the design
requirements for the power distribution topology of a main board.
Decreasing the heat dissipation in a system chassis or portable PC by 12
to 20 per cent of CPU consumed power. The same applies to the chips of a
“North bridge” (data bus controller). The remaining heat dissipation
makes less than 1 per cent of a usual filter. In portable computers this
allows installing more powerful processors with current cooling systems.
Decreasing the CPU heating by 1 to 5 per cent due to absorption of
high-frequency part of CPU-generated interference by the last part of
Increasing the anti-jamming capability of main board units by
high-quality filtering of the consumed voltage. Such filtering excludes
spreading of CPU-generated interference to other circuits via parasite
Lowering the level of high-frequency radiation in a system chassis due
to filtration improvement and, as a result, total suppression of power
distribution circuits radiation. This as well increases the anti-jamming
capability of a system and excludes re-radiation of CPU-generated
interference from power distribution circuits outside a system chassis.
As a consequence, information security improves.
2. Applying The Filter to the power supply of extension cards installed
into PCI and AGP slots of a main board is implemented by placing the
last part of The Filter (and the last but one, if necessary) on a unit
being protected. The rest parts are placed on main board’s power
2.1. Effect of applying The Filter to video cards.
The cost of video cards production can be lowered due to an ability of
using cheaper oxide condensers in processor power circuits. In some
cases it is possible to give up using condensers at all.
Applying The Filter decreases the temperature of video processor and
memory chips by 1 to 5 per cent, increases the stability of their
operation by improved filtration of induced voltage jamming in power
distribution circuits of video card processor. As a result of applying
The Filter, the heat dissipation produced by the power of interference
generated by video processor and memory decreases down to 12 to 20 per
cent of consumed power. The radiation level of interference generated by
video processor is lowered as well.
2.2. Effect of applying The Filter to memory modules.
Applying The Filter lowers the temperature of chips by 1 to 5 per cent,
increases the stability of their operation by improved filtration of
induced voltage jamming in power distribution circuits of memory
modules. Moreover, applying The Filter decreases the temperature of
filter elements and power control of a main board’s memory modules,
which allows using cheaper oxide condensers and eliminating inductance
chokes. The radiation level of interference generated by memory chips in
power distribution circuits is lowered as well.
Applying The Filter to power circuits of memory modules should be
complex. It means that integrating The Filter into main board’s power
circuits for memory modules supply should be accomplished with
installing the last part right near the chips and the last but one on a
2.3. Effect of applying The Filter to audio cards.
Applying The Filter improves the filtration of consumed voltage in whole
frequency spectrum range: from processed audio signal to the speed of
audio card processor. As a result, the mutual spreading of signals
between channels via power distribution circuits is decreased, as well
as the level of noise produced by invasion of processor-generated
interference into analog output circuits. The Filter diminishes
nonlinear distortions in high-frequency part of operation range caused
by voltage fluctuations synchronous with a processed signal.
As in other cases, applying The Filter allows using cheaper oxide
condensers in a power filter.
3. The peculiarities of applying The Filter to video cards with a
separate connection to the system power supply and the obtained effect.
Modern high-speed video cards use direct power input from the main
system power supply. This is the consequence of the large power
consumption of such cards. In this case all the effects specific to main
boards show up on these video cards. In the same way, all the technical
effects of applying The Filter propagate to such cards. The economical
effect in analogous as well. See section 1.
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