L Match Topology; Figure 2-2. L Match Network Circuit; Figure 2-3. Variomatch L Match Network Circuit - Advanced Energy VarioMatch Match Network VM 1000 Platform User Manual

L Match Topology

Figure 2-1 shows a basic L match network circuit.
50 Ohms
RF-Generator

Figure 2-2. L match network circuit

The L match network received its name because of the configuration of the capacitor
and coil used. The L match network is simple, and requires only two tuning
elements-a series (or tune) coil and a shunt (or load) capacitor.
In practice a quality variable coil cannot be economically constructed because a
sliding tap to the coil cannot withstand a high RF current. The typical 5 A RF rating
for a highly variable coil isn't suitable for plasma loads with their high associated RF
currents.
As a result of these limitations, the traditional L match network is modified by the
installation of a variable capacitor connected in series with a fixed or tapped coil.
Figure 2-1 shows a typical V arioMatch
50Ohms
RF-Generator

Figure 2-3. VarioMatch L match network circuit

In principle, the L match network is a good choice when the load impedance is not
known and must be determined by experimentation. If the match network uses
inductors and capacitors with very wide tuning range, nearly any impedance can be
properly matched.
The tune coil is connected in series with the wiring to the load. The inductance of the
wire connecting the match network to the load must be considered to be a part of the
tune coil. Because of this, ensure that this wiring is as short as possible and low
inductance. Short connection leads will help to reduce EMI. The V arioMatch match
network must be well grounded to the load.
57020080-00D
AE VarioMatch
TM
Series (Tune) Coil
Shunt (Load)
Capacitor
L match network circuit.
Tune Capacitor
Load
Capacitor
Product Overview and Theory
Match Network, VM 1000/1500 Platform
r
Load
Impedance
(Plasma)
3260
r
Load
Impedance
(Plasma)
3261
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