METHOD AND APPARATUS FOR INCREASING THE BANDWIDTH, AND REDUCING THE SIZE, OF THE DC FEED NETWORK FOR WIDEBAND RF AMPLIFIERS

摘要

For use with RF circuitry in which a DC bias circuit provides a bias voltage to an impedance-matched circuitry, a structure is provided, in which a dielectric member, having a high dielectric constant, is selectively placed adjacent to a bias feed line coupled betwee the DC bias circuit and the remainder of the circuitry, to maintain high RF impedance while reducing impedance at lower frequencies. The invention has particular applicability to RF amplifiers, to be used for amplifying modulated carriers, such as video signals made up of an RF carrier and a lower-frequency modulation. Where the carrier has a predetermined wavelength, the physical length of the bias feed line and the dielectric constant of the dielectric member are chosen such that an effective length of the bias feed line is a quarter of the wavelength of the carrier.