Balanced Amplifier Design for Improvement of Reverse Intermodulation Distortion in Wireless Microphone Systems

A central topic dealing with two important aspects of wireless microphone systems, spectral efficiency and interference robustness, is the so-called transmitter (TX) or reverse intermodulation distortion (RIMD). This self-made nonlinear distortion, originating from the systems transmitter output stage, pollutes the spectrum and desensitizes co-located receivers. This paper presents a balanced circuit topology for the output stage of the TX, that is capable of reducing not only RIMD by up to 24.4 dB, but also improves adjacent channel leakage ratio (ACLR) and 2$^{nd}$ and 3$^{rd}$ harmonic distortion by more than 6 dB.