Nowadays consumers' electronic devices are highly integrated, and modules and integrated circuits (ICs) are usually placed close to each other due to the compact size. The modules and ICs may interfere with the radio frequency (RF) antennas and cause desense issues. In recent years, desense caused by direct coupling from the noise sources to the victim RF antennas has been well studied. However, more complicated mechanisms such as modulations between transmitting signals and low-frequency clock or data signals can also result in desense problems, especially in frequency divide duplex (FDD) applications. Typical solutions to desense problems will focus on suppressing the noise sources and/or the coupling paths, and little studies have shown the feasibility that desense in FDD applications can also be mitigated by engineering the spectral power distribution over the frequency range. This paper provides a comprehensive study on how to mitigate desense with the change in the spectrum distribution by tuning the duty cycle of the interfering clock. Measurements conducted on a real cellphone showed a 10 dB suppression of desense for certain TX bandwidth condition.