
PlasmaQuant MS Series
Plasma
Generation
63
Figure 6-5 - Redline DC power supply
Figure 6-6 - H-Bridge circuit used to create 27 MHz plasma
During normal operation, an “induced” voltage, originating from two separate strip-
line transformers located inside the RF generator, enables the gates on the FETs. The
transformers enable the gates of the FET’s diagonally so the RF power supply applies
voltage to both sides of the load coil. This voltage, in turn, dissipates to zero as it
reaches the center of the coil.
The duration of time that each set of FETs remains enabled equals a half-cycle of the
overall oscillator timing circuit. During the first half-cycle, induced voltage from K3 and
K1 enable the gates on FETs X2 and X3. Likewise, during the second half-cycle,
induced voltage from K4 and K2 enable gates on FETs X1 and X4.
A DC power supply provides up to 190 V on V1 and is controlled by the firmware.
During normal operation the potential from the power supply is about 180 V.