专利名称：AM-FM transmitter power amplifier using
class-BC
发明人：Paul W. Dent申请号：US08/321446申请日：19941012公开号：US05570062A公开日：19961029
摘要：A power amplifier circuit for efficiently generating an output signal into a loadat more than one alternative power level has at least two amplifiers, each havingoptimum efficiency at different power output levels. The power amplifier circuit may beoperated in several modes, including activating one amplifier during an entire cycle of aninput signal to be amplified, or alternatively activating one amplifier based on a controlsignal that is independent of the amplified output signal. In either case, remainingamplifiers are deactivated. Coupling between the amplifiers prevents deactivatedamplifiers from impeding the flow of power from the activated amplifier to the load. Inanother aspect of the invention, optimum efficiency at different power output levels isachieved by means of coupling each amplifier to a common power source and to the loadvia an impedance matching circuit, the impedance transformation being different fordifferent amplifiers. The impedance matching circuit may comprise a push-pull
transformer having taps to provide different turns ratios between respective amplifiersand the load. Alternatively, the matching circuit may comprise a number of quarter-wavelength lines each coupled at one end to the load and at the other end to one of theamplifiers via a balun.
申请人：ERICSSON GE MOBILE COMMUNICATIONS INC.
代理机构：Burns, Doane, Swecker & Mathis, LP.
更多信息请下载全文后查看
因篇幅问题不能全部显示，请点此查看更多更全内容