Abstract: An RF amplifier system having closed cavity containing an amplifying device that includes at least a cathode, an anode and a grid and wherein the amplifying device exhibits an internal grid-to-anode capacitance. Apparatus is presented for use in neutralizing the internal capacitance. This includes a feedback circuit including an external capacitor of fixed value and a phase inverting transformer having a transformer primary winding connected in series with the capacitor to the cathode. The transformer has a secondary winding connected between the cathode and the grid for supplying a phase inverted negative feedback voltage to the grid for neutralizing the cavity by the feedback voltage. The transformer coupling is adjustable to vary the magnitude of the feedback voltage.
September 11, 2009
Date of Patent:
January 4, 2011
David Christopher Danielsons, Geoffrey Norman Mendenhall