| 摘要 |
Apparatus and method for parallel operation of radio frequency transistor amplifier circuits in a Class D mode of operation at radio frequency signal ranges without the use of frequency limiting components is disclosed. A driver circuit provides the input signals for each radio frequency transistor amplifier circuit. A transformer is disclosed that combines the output signals of the radio frequency transistor amplifier circuits while matching the amplifier circuit impedance and the transformer load impedance (i.e., the antenna impedance). The transformer eliminates the need for DC blocking capacitors between the primary and secondary windings of the transformer. The transformer/power combiner includes a plurality of (1:1) transformer units having the unit input terminals (power amplifier output signals) coupled in parallel and having unit output terminals coupled in series. The parallel/series configuration permits impedance matching of the power amplifier output impedance and impedance driven by the transformer. The primary structure of the unit transformer is metal sleeve surrounded by a ferrite core. The secondary winding includes at least one conductor cable inserted through the metal sleeve. The metal sleeve is coupled between the power amplifier output terminal and the DC power source. |
