The paper presents a discussion on differential active balun circuit in terms of the dynamic range, designed and implemented in a 90nm complementary metal-oxide semiconductor (CMOS) technology. Dynamic range can be derived using noise analysis, and is an important design consideration as it determines the vulnerability of the circuit to unwanted signals such as noise. It is therefore critically important that the differential active balun circuit contributes as little noise as possible especially in the system level design of radio frequency (RF) applications.