Patent Number: 6,674,329

Title: Distributed RF amplifier with filtered dummy load

Abstract: A distributed amplifier consistent with certain embodiments of the present invention has a plurality of amplifier sections 1 through N (302, 306) with each amplifier section having an input and an output. A plurality of N input transmission line sections are connected in series, with inputs of the 1 through N amplifier sections interconnected at their inputs along the series of input transmission line sections. A plurality of N output transmission line sections are also connected in series, with outputs of the 1 through N amplifier sections interconnected at their outputs along the series of input transmission line sections. A load (160) can be driven by an output at the Nth amplifier section (108). A high-pass filter (310) connects a dummy load (150) to the output of the first amplifier section (302). The input and output transmission line sections can, for example, be lumped element T sections and the high-pass filter can be made of a lumped element half section. To achieve the desired stability enhancement, the high pass filter section has a cutoff frequency equal to or greater than the cutoff frequency of the output transmission line sections. A similar high pass filter and dummy load can be used in the input transmission line network.

Inventors: Stengel; Robert (Pompano Beach, FL), Cafaro; Nicholas Giovanni (Coconut Creek, FL)

Assignee: Motorola, Inc.

International Classification: H03F 3/60 (20060101); H03F 003/60 ()

Expiration Date: 01/06/2021