| 摘要 |
An RF power amplifier for amplifying an RF signal over a broad range of power with improved efficiency includes a main amplifier (20) 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. A plurality of auxiliary amplifiers (21, 22, 23) are connected in parallel with the main amplifier (20) with each of the auxiliary amplifiers (21, 22, 23) being biased to sequentially provide an amplified output signal after the main amplifier (20) approaches saturation. The input signal is applied through a signal splitter (32) to the main amplifier (20) and the plurality of auxiliary amplifiers (21, 22, 23), and an output for receiving amplified output signals from the main amplifier (20) and the plurality of auxiliary amplifiers (21, 22, 23) includes a resistive load R/2. The split input signal is applied through a 90~ transformer (30) to the main amplifier (20), and the outputs of the auxiliary amplifiers (21, 22, 23) are applied through 90~ transformers (24, 25, 26) to a output load (28). When operating below saturation, the main amplifier (20) delivers power to a load of 2R and the main amplifier (20) delivers current to the load which is one-half the current at maximum power and the amplifier is saturated.
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