Systematic waveform engineering enabling high efficiency modes of operation in Si LDMOS at both L-band and S-band frequencies

This paper demonstrates that by robust waveform engineering it is possible for high power Si LDMOS to achieve very high efficiency at frequencies up to 2.1GHz. Class F amplifier operation was realized in a 5W LDMOS device by the successful application of robust waveform engineering procedures; undertaken at the current generator plane. The peak power added efficiency was found to be 78% at 0.9GHz and 77% at 2.1GHz. In both cases the RF waveforms were optimized in terms of the gate voltage, fundamental and harmonic impedances. The main difference at 2.1GHz was the change in fundamental impedance to a more reactive impedance to compensate for the dynamic device output capacitance. To the authors' knowledge this is the highest efficiencies reported in the literature for Si LDMOS devices at 2.1GHz. © 2008 IEEE