标签: designrfcircuit

DesignRFCircuit“HowtoDesignRFCircuits”-OSCILLATORSAndrewDearn*IntroductionOscillatorscangenerallybecategorisedaseitheramplifierswithpositivefeedbacksatisfyingthewellknownBarkhausenCriteria(Ref.1),orasnegativeresistancecircuits(Ref.2).BothconceptsareillustratedinFigure1.AtRFandMicrowavefrequenciesthenegativeresistancedesigntechniqueisgenerallyfavoured.+veFeedbackLC-veRRAmplifier(a)NegativeResistanceOscillator(d)PositiveFeedbackOscillatorFigure1:GeneralEquivalentCircuitsforRFOscillatorsTheprocedureistodesignanactivenegativeresistancecircuitwhich,underlarge-signalsteady-stateconditions,exactlycancelsouttheloadandanyotherpositiveresistanceintheclosedloopcircuit.Thisleavestheequivalentc……