Efficient FIR interpolation circuit using supplementary filter

Interpolation filters are widely used in symbol timing recovery systems to interpolate new sample values at arbitrary points between the existing discrete-time samples. Polynomial interpolation computes the coefficients of the polynomial according to the input information to obtain the position value. In this paper, we propose an efficient way to implement the third-order Lagrange interpolation circuit by introducing a supplementary filter. Examples and simulation results show that the proposed approach is more efficient compared to the conventional interpolation methods.