User's Manual

RF Technology Page 7
2 CIRCUIT DESCRIPTION 2.2 Power Splitter / Combiners
No trimmer capacitors or inductors are used for input/output matching, the broadband
design means no re-adjustment is required even if the frequency is changed from one
end of the band to the other.
The dc supply is fed to the amplifiers through resistors R166 and R167. This allows
the current of each amplifier to be monitored.
2.2 Power Splitter / Combiners
In the 100W models, a zero-degree broadband splitter and zero-degree hybrid
power combiner is used to parallel the two amplifier stages. This configuration provides
a very wide bandwidth and better balance compared with lower cost 90-degree hybrids.
2.3 Directional Coupler
The forward and reverse power components are measured through an asymmetric
stripline directional coupler. The output of the coupled lines measured by two
temperature and frequency compensated detectors.
2.4 Low Pass Filter
A low pass filter consisting reduces the harmonic components to less than -90dBc. The
filter uses shielded lumped elements to obtain the required harmonic attenuation.
2.5 Power Control Circuits
The forward and reverse voltages from the directional coupler are amplified and
combined in the ALC error amplifier.
The Error amplifier compares the detected voltages with the dc reference voltages from
output power trimpot RV1 and reverse power trimpot RV2. The amplified difference is
used to control the output power of the RF MOSFET Modules.
E2-IP-PA 500BH