This paper proposes a new non-parametric method to estimate the power spectral density using filter banks through polyphase approach. The performance of proposed method is investigated for a simulated broadband and narrowband Signals. The proposed method reduces the variance without adversely affecting the resolution. The variance reduction is observed to be more in case of narrowband signals. The proposed method has the computational cost similar to modified periodogram approach. Index Terms - Spectral estimation, non parametric, polyphase approach, uniform filter banks, modified-periodogram, P th order spline FIR filter, broad and narrow band signals, resolution, variance, bias. ©2008 IEEE.