Doherty Power handling
Doherty power amplifiers are capable of amplifying the
signals of high Peak to Average Ratio (PAR) with high
efficiency. A 1:1 symmetrical Doherty architecture is
typically used for signals of 6-10dB PAR.
To evaluate power handling capability, the doherty
combiner is analyzed in different conditions of varying
PAR that the component would see in its lifetime.
Condition 1: In symmetrical Doherty application, at
average power condition, the Doherty amplifier works at
back off mode and turns on only main amplifier with half
of its full power capacity. The thermal condition of Anaren
Doherty combiner is evaluated as an impedance
transformer.
X3DC21P1S can handle reliably for life 35 watts at main
amplifier and 0 watts at peak amplifier when evaluated as
impedance transformer.
Condition 2: Doherty amplifier ramps up the main
amplifier to 65% its full power capacity and peak amplifier
to 30% of its full power capacity, outputting power
roughly 3dB above the average. The thermal condition of
Anaren Doherty combiner is analyzed as a coherent
combiner and such power level is assumed continuously
over entire life span of the component. Although
conservative and limit the components power rating, it is
done so to guarantee the life time of the components
over high PAR signals.
X3DC21P1S can handle reliably for life 46 watts at main
amplifier and 21 watts at peak amplifier when evaluated
for condition 2.
Condition 3: Signals of 3dB and above the average
power occur with low probability and short duration and
they do not present thermal risk. With high breakdown
voltage, Anaren Doherty combiners can safely withstand
at least 12dB peaks over the average rated power.
X3DC21P1S can handle reliably for life 70 watts at main
amplifier and 70 watts at peak amplifier when evaluated
for peak pulses of very short duration.
The power handlings of Anaren Doherty combiners are
conservatively rated at averaged power with high PAR
signal and Doherty operation in mind. The combiners
can be used in Doherty amplifiers of rated average output
power. No further power derating for high PAR signals is
required
