General Comb Filter

Combining both the feedforward and feedback comb filter yields the general comb filter, given by the difference equation

$$y(n) = x(n) + g_1x(n-M_1) - g_2y(n-M_2)$$

where $g_1$ and $g_2$ are the feedforward and feedback coefficients, respectively.

Figure 12: Signal flow diagram for digital comb filters.

Figure 13: Comb Filter Impulse Response.