The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 20, 2003
Filed:
Mar. 19, 2001
Masami Ohnishi, Hachiouji, JP;
Akira Maeki, San Jose, CA (US);
Hitachi, Ltd., Tokyo, JP;
Abstract
A high frequency power amplifier is provided that prevents loop oscillation at a low frequency caused by a closed loop formed between combined semiconductor devices. Previously, coupled-line directional couplers or capacitors for low frequency rejection have been used to prevent the closed loop from being formed. Also, a circuit including a resistance component required for attenuating self-oscillation has been provided. Therefore, to prevent both loop oscillation and self oscillation, two circuits have been required. Accordingly, a high frequency power amplifier is provided with a low frequency prevention circuit that attenuates the passing of each frequency of loop oscillation and self oscillation to each signal line divided by a power divider. Thus, the two circuits respectively required for preventing the loop oscillation and self oscillation of a travelling wave combine type amplifier can be formed by one low frequency prevention circuit.