Multitone signal study

When an amplifier is used to amplify a number of carriers at different frequencies with or without amplitude modulation, the envelope of the sum of the different signals can cover a wide range of voltage or input power. This wide range of amplitude results in both inefficient operation and high intermodulation products when conventional amplifiers are used. It is proposed to improve both the efficiency and linearity by using the envelope of the input signal to modulate the instantaneous input power to the device. In order to maximize the efficiency, it is shown that fixed delays in each signal circuit before addition can be used to minimize the voltage range for any given number of signals at either random frequencies or at specifically allocated channel frequencies.