Motorola Corporation

Gilberto Jacinto Hernandez

Edgar Herbert Callaway, Jr

Douglas H Weisman

Raymond Louis Barrett

A method and apparatus for a highpass filter structure using transmission line construction which has multiple output tabs for selection of corner frequencies utilizing a plurality of resonators coupled to the transmission line. The transmission line has a characteristic impedance which increases exponentially with respect to a distance from the input.

Method and apparatus for a communications filter

A transmission line ( ) is formed to have a characteristic impedance which increases at a first substantially exponential rate with respect to a distance from the input ( ). A plurality of resonators ( ) are coupled to the transmission line and positioned at a plurality of locations along the transmission line. The plurality of resonators has resonant frequencies that decrease at a second substantially exponential rate with respect to the distance from the input. An output signal ( ) is obtained at a point in the filter that produces a filter response having a corner frequency.

Method and apparatus for creating a radio frequency filter

A tunable filter ( ) includes first ( ) and second ( ) &ldquo;bridged-T&rdquo; resonators. The first ( ) and second ( ) resonators are capacitively coupled together via bandwidth control/coupling section ( ). A biasing section ( ) provides the proper biasing and decoupling for the filter ( ). Filter ( ) provides for low-side injection mode operation, and provides for a very deep zero on the lower side of the passband resulting in excellent selectivity. Filter ( ) provides for excellent selectivity while reducing the number of inductors and varactors needed in the filter circuit. A high side injection mode filter ( ) similar to filter ( ) is also described in the disclosure.

Tunable bridged-T filter

A tunable filter (400) provides dual injection mode operation over a continuously tunable frequency range (500). A combination of mirrored series resonant circuits (432, 446) tuned through varactors (434, 448) allows the frequency response to shift. The use of a series capacitor and shunted inductor (430, 428), (444, 442) mirrored onto each series resonator (432, 446) provides both high-side and low-side injection protection.

Growing community of inventors

Miami, FL, United States of America

Gilberto Jacinto Hernandez