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Dan Bobyn |
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VHF Multicarrier PA and Power
Control Loop This
program consisted of refining an existing 100W VHF PA design to be capable of
operating at selectable maximum operating output power levels (16, 50,
100 W), and to incorporate automatic output power control to maintain the
output power level over a wide range of input power levels and modulation
conditions. An
active bias feedback circuit was used to desensitize the device operating
point to variations in temperature, and unit to unit variations. The feedback reference point was varied to
optimize the device bias conditions at the three output power levels. The aim was to maximize the PA operating
current for variable operating conditions.
A
feedback circuit to control the output RF power level of the PA was also added
to the hardware to ensure PA was operating at an optimum RF level for the
selected PA output power level The program required expertise in high power RF circuit design, feedback loop modeling and linear and nonlinear circuit simulations. |
© 2010 Dan Bobyn Engineering Ltd.