Moving Average FIR Filter to Validate Li-Ion Battery Termination Current

This article presents a finite impulse response (FIR) moving-average filter for validating noisy analog signals. While the conventional sliding-window implementation is computationally efficient, it requires storing the last N − 1 samples, leading to significant memory usage for large windows. To address this limitation, an alternative method is proposed that avoids full sample history storage by integrating the filter state with incoming samples. Under slowly varying input conditions, the proposed circuit reproduces the behavior of a conventional moving-average FIR filter. The approach is applied to a charger controller for validating the termination current of a lithium-ion battery, demonstrating reduced memory requirements and simplified implementation.