Analysis and Optimization of a Third-Order Filtering Transimpedance Amplifier for an Interferer-Tolerant RF Receiver

Modern wireless communication systems, particularly 5G networks, require RF receivers capable of operating in highly congested spectral environments with strong out-of-band interferers while maintaining high sensitivity. The Transimpedance Amplifier (TIA) in RF receivers plays a critical role, as it must simultaneously achieve adequate filtering, low noise figure, high linearity, and reasonable power consumption, forcing a careful trade-off among these metrics. After introducing the key concepts of duplexing (TDD and FDD) and the role of the receiver chain (LNTA, passive mixer and TIA), this work focuses on the analytical optimization of a third-order filtering TIA based on a modified Tow-Thomas topology (Lecchi’s TIA). The proposed optimization provides significant improvements across all performance metrics. Optimal pole placement enhances out-of-band rejection by 3.5 – 5 dB compared to the reference implementation. Detailed noise analysis of individual contributions leads to design choices that can reduce the integrated output noise by approximately 50%. Linearity is improved through careful stage-gain balancing, along with strategic power budget allocation aimed to mitigate compression and distortion mechanisms. Finally, a performance comparison among different topologies validates the methodology, providing RF designers with a systematic path from specifications to practical implementation for wireless receivers.