A system includes a first differential amplifier and a first transformer with a primary coil coupled to an output of the first differential amplifier and with a secondary coil coupled to a load. The system also includes a second differential amplifier and a second transformer with a primary coil coupled to an output of the second differential amplifier and with a secondary coil coupled in series with the secondary coil of the first transformer. The system also includes a tuning network coupled to a center tap node between the secondary coil of the first transformer and the secondary coil of the second transformer.