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. 30, 1995
Filed:
Jun. 04, 1993
David M Upton, Mont Vernon, NH (US);
Robert J McMorrow, Boston, MA (US);
Raytheon Company, Lexington, MA (US);
Abstract
An improved Doherty amplifier for operation at microwave frequencies using microstrip circuit technology and gallium arsenide devices to achieve greater efficiency and linearity. The circuit divides the input power equally between a carrier amplifier and peak amplifier with a quarter-wave delay at the input to the peak amplifier insuring that the output power of the two amplifiers will be in phase at the load. A three-port network combines the phase-delayed carrier amplifier output with the output of the peak amplifier. The outputs of the two amplifiers are connected together by a quarter wave transmission line of impedance R. A load of one-half the optimum load (R/2) is attached to the output of the peak amplifier. A quarter-wave line section provides the transition from R/2 to the desired impedance, R. When the peak amplifier is off, its output impedance is infinite and the output power of the carrier amplifier is delivered entirely to the load. As the peak amplifier becomes more active, it delivers more of its output power to the load while its output current gradually reduces the effective load impedance seen by the carrier amplifier thus allowing it to deliver more power. In this way the microwave Doherty amplifier allows 6 dB of linear power amplification beyond the point where a normal Class 'B' amplifier begins to saturate and the microwave amplifier efficiency remains close to the maximum attainable linear efficiency.