Advances in active down-conversion mixer linearity techniques: a comprehensive review

In the modern era, the demand for high-speed communication has led to a growing preference for higher bandwidth. However, in wideband scenarios, the presence of neighboring bands can introduce nonlinearity issues in mixers. The RF stage and Switching stage are identified as the primary contributors to nonlinearity in down-conversion mixers. This article presents a basic principle as well as circuit architectures of the mixer, including a performance parameters comprehensive review of linearity improvement techniques employed in down-conversion mixers. The paper categorizes various previously reported methods to enhance the linearity of the RF stage into five approaches: (1) MGTR/Derivative superposition (DS), (2) Complementary DS (CDS), (3) noise cancellation (NC), (4) post distortion (PD), and (5) feedforward or feedback approach. These techniques aim to enhance the Second-order nonlinearity ( \(g_{m}^{\prime }\) $g_m^{\prime }$ ) or third-order nonlinearity ( \(g_{m}^{\prime \prime }\) $g_m^{″}$ ) of the RF stage. Among these approaches, Noise Cancellation (NC) methods demonstrate superior optimization in terms of Conversion Gain, Linearity, and Noise Figure. Furthermore, to improve the linearity of the switching stage in mixers, the static and dynamic current injection methods can be employed. The objective of this review is to contribute to the advancement of linearity improvement techniques for wideband active down-conversion mixers, while also facilitating future research and development in this field.