Receiver Design Techniques to Maintain Sensitivity in the Presence of Large Blockers

Achieving high sensitivity is key in receiver design to maintaining data reception in a wireless communications link and in locating targets in a radar system at long distances. Good sensitivity requires high receiver gain to sufficiently amplify the received signal to a level which can be digitized with good signal-to-quantization-noise (SNR) by an ADC. However, wireless systems operate in environments where blockers are present from other wireless devices in mobile applications and from the device’s own transmitter in FDD and full-duplex systems. These blockers can be orders of magnitude stronger than the desired signal and could saturate the RF front-end, preventing reception of the desired signal. This tutorial presents the fundamental challenges blockers present to receivers, including saturation, harmonic down-conversion, and nonlinearity artifacts. The tutorial presents approaches for mitigating these effects and maintaining sensitivity including harmonic rejection receivers, N path filters, mixer first receivers, and recent approaches for full duplex operation.