| 摘要 |
A switched-mode power amplifier is configured for performing power amplification of a plurality of signals input thereto and integrally summing (combining) those signals. Conceptually, this is achieved by replacing the center-tapped input winding component of the transformer within a conventional, balanced-type transformer-coupled voltage switching amplifier with separate input components, one for each input signal, in similar manner to the configuration of the input components of a conventional three-port combiner (trifilar) or two transformers having their output (secondary) windings series connected. Accordingly, the input winding of the amplifier's transformer is comprised of a plurality of series-coupled windings, one for each of the plurality of input components/signals. In one embodiment, using balanced amplifier input components comprising series-coupled center-tapped windings, the center tap of each input winding (72,74) is connected to a voltage rail (VDD) and each terminal end of the winding (72,74) is driven by an amplifying active device (82,84,86,88) (i.e. transistor) fed by the input signals for that input component. These active devices (82,84,86,88) alternately switch between a low output impedance and a high output impedance whereby the resulting parallel output impedance is low. |
