How can even-order harmonics be reduced in a transmitter amplifier design?

Even-order harmonics arise in circuits when there is a lack of symmetry in the signal's waveform, which can be effectively reduced using a push-pull amplifier configuration. In a push-pull amplifier, two devices (usually transistors) are used to amplify the positive and negative halves of an input signal. This design inherently cancels out even-order harmonics because the harmonic content generated by one transistor during its operation is countered by the opposite operation of the other transistor.

In contrast, other amplifier types may not provide this level of harmonic cancellation. For example, single-ended amplifiers typically have asymmetrical signal handling and are prone to generating both odd and even-order harmonics without the balanced input/output characteristics that a push-pull design facilitates. Similarly, while class C amplifiers are efficient for radio frequency signals, they are not specifically designed to mitigate even-order harmonics like a push-pull arrangement. Increasing input signal power does not address the harmonic distortion issue directly, as it does not change the fundamental properties of the amplifier's design.

Thus, the push-pull amplifier's capability to reduce even-order harmonics makes it the best choice in this context.