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:
Sep. 14, 2004
Filed:
May. 05, 2003
Raymond Sydney Pengelly, Hillsborough, NC (US);
Simon Maurice Wood, Sunnyvale, CA (US);
Cree Microwave, Inc., Sunnyvale, CA (US);
Abstract
An RF power amplifier circuit for amplifying an RF signal over a broad range of power with improved efficiency includes a carrier amplifier for amplifying an RF signal over a first range of power and with a power saturation level below the maximum of the broad range of power is disclosed. A plurality of peak amplifiers are connected in parallel with the carrier amplifier with each of the peak amplifiers being biased to sequentially provide an amplified output signal after the carrier amplifier approaches saturation. The input signal is applied through a signal splitter to the carrier amplifier and the plurality of peak amplifiers, and an output for receiving amplified output signals from the carrier amplifier and the plurality of peak amplifiers includes a resistive load R/2. The split input signal is applied through a 90° transformer to the carrier amplifier, and the outputs of the peak amplifiers are applied through 90° transformers to a output load. When operating below saturation, the carrier amplifier delivers power to a load of 2R and the carrier amplifier delivers current to the load, which is one-half the current at maximum power when the amplifier is saturated. In one embodiment with the output having an impedance, Z, the carrier amplifier and each peak amplifier is connected to the output through an output-matching network presenting an output impedance of less than Z to each amplifier and with each output-matching network having selected phase length to reduce reactance of the output impedance.