Application Note 1811
October 2013
www.microsemi.com
7/10
Figure 6. Peak VDS (PS HV = 300V)
CONCLUSIONS
This application note is for a reference design using a DRF1200 as a CLASS-E RF generator. The high performance
DRF1200 Hybrid was used because it includes both the driver, Power MOSFET, and bypass capacitors optimized to
reduce inductance and achieve a single low-cost solution. A reference design board is available to demonstrate this
high efficiency, 1KW, 13.56MHz RF generator with 86% efficiency using a drain supply voltage up to 320Vdc.
The critical aspects such as the layout of components for efficient power generation, testing, and air cooling
requirements are also discussed.
Test Setup
It is highly recommended that a Common Mode Choke (CMC) is used on all power and measurement inputs and
outputs. This approach provides the best stability and the most accurate measurements.
Construction of CMC’s are illustrated below. The CMC on the left should be used for PS 1 and the PS 2 inputs.
These lines are tightly twisted pairs (5-8 twists per inch). The CMC on the right should be used for the Scope Probe
Cable. Three to five turns on each is sufficient. The CMC’s should be placed as close to the DRF1200/CLASS-E
Board as practical. Bench test pictures are included where Fair-Rite part number 0431164181 has been used in
three places for power supply isolation.
Cable EMI Suppression Core
Twisted Pair
CMC for +15
V and
HV DC Power
Cable EMI Suppression Core
Coaxial Cable
CMC for Scope Control
and Signals
