URSI 2007, XXII Simposium Nacional de la Unión Científica Internacional de Radio, La Laguna
In this paper, we present the design of a high
efficiency class-F power amplifier in pHEMT technology
using an accurate WREN/COBRA model at 2GHz. The
transistor is overdriven into compression in order to
maximize efficiency and output power. Three concepts of
output matching networks are used in the design of class F
power amplifiers, based on harmonics output terminations,
that is shown to have a critical influence on PA performances
when compared to a classical class B power amplifier
(PAE= 61.56%, Pout=12.14 dBm). The design of the first
amplifier is based on 2nd harmonic termination while all
other harmonics are open circuited where the output is seen
to consist of a half-wave rectified voltage waveform. 87.37%
saturated PAE and 12 dBm output power are obtained for
this amplifier. In the second amplifier, the 3th harmonic is
terminated and the output is seen to consist of a square wave
voltage waveform. This amplifier result in 72.87% saturated
PAE and 12.52 dBm output power. Finally, following a
detailed theoretical analysis, a class F matching network that
suppress the necessary load harmonics, is used for the design
of the third amplifier. The saturated PAE delivered is
74.19%, the output power is 12 dBm and a square wave
voltage waveform is obtained at the output.
