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150Watt Impedance
Matching Networks Manual and Automatic Coaxial Power Systems Ltd
manufacture two styles of impedance matching network to link the load to the RF
generator. The purpose of the network is to adjust the input impedance of the
load to 50 Ohms so that maximum power is transferred from the generator, whose
output impedance is 50 Ohms, to the load. Coaxial Power Systems Ltd.
manufacture two types of network - Manual and Automatic
The manual matching
network consists of two adjustable air vane capacitors and a fixed inductor,
which are usually arranged as an ”L” network. (The arrangement can be simply
converted to a “Pi” network if required). Geared drives with vernier dials
are used to adjust the capacitors for minimum reflected power as displayed on
the generator reflected power meter. When the reflected power is zero, the
system is “tuned” and all of the power output of the generator is being fed
to the load. Two models, rated at 150W max. or 600W max. are available
The automatic matching
network is similar to the manual version except that servomotors drive the
capacitors. At the input of the
network, a phase and magnitude detector determines the position of the
capacitors. This information is transferred to the separate controller. The
controller then drives the servomotors to the positions, which give zero, or
minimum reflected power.
The position of each
variable capacitor is shown on a 31/2 digit LED meter. Automatic or Manual mode
is switch selectable - in manual mode the servomotors are controlled by spring
loaded switches. The start position of the
capacitors can be individually adjusted. When RF power is detected, the
capacitors automatically adjust for minimum reflected power. When the RF is
turned off, the motors drive the capacitors back to heir original position. The
start positions are adjusted using potentiometers accessible via the controller
front panel Option: Model DCP-1 : Dark Space Bias Voltage Measurement and Control A
probe, installed inside the network, measures the d.c voltage (0 to 1999V)
developed across the dark space in plasma applications such as sputtering and
reactive ion etching. The voltage is converted to a 0 to 5V signal which can be
fed back to the generator control system. The voltage is displayed on the loading capacitor position meter.
Includes all necessary cables to link to any generator in the low power range
manufactured by Coaxial Power Systems Ltd. Note:
This option not available on manual networks (07.06.2007) |
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