A Digitally Assisted Nonlinearity Mitigation System for Tunable Channel Select Filters

This brief presents a low-complexity system for digitally assisting a channel select filter (CSF) to mitigate both even- and odd-order nonlinearities. The proposed solution is scalable and can be utilized for nonlinearity mitigation in different analog transceiver blocks. The system consists of an auxiliary path with a low-resolution analog to digital converter (ADC) enabling digital recreation and measurement of the distortion in the main path and relies on an adaptive digital signal processing algorithm to detect and tune the analog components to their optimal settings. The system provides robustness against process, voltage, and temperature variations, and the digital part requires an equivalent logic of only 42 k gates in CMOS technology, enabling cost-efficient implementation on integrated circuits. The operation of the system has been verified by using a tunable CSF capable of receiving a 10-MHz baseband signal interfaced to an external ADC. The results demonstrate that the proposed system is capable of tuning the CSF to its optimal bias voltage, providing a third-order intermodulation reduction of 14.5 dB.