5-tap FIR Low-pass Filter

The module computes the discrete convolution of signed samples i_sample with a fixed 5-coefficient set (low-pass triangular window 1, 2, 4, 2, 1).

Required structure: direct form:

• a 5-register line buffer stores the last 5 samples,
• each sample is multiplied by its coefficient,
• the 5 products are summed combinationally,
• the sum is latched by an output register.

A new sample is consumed on each i_valid='1' pulse. Output o_sample is valid with o_valid='1' one cycle later. Synchronous active-high reset.

Generics:

• g_DATA_WIDTH : positive (default 16) - signed sample width
• g_COEF_WIDTH : positive (default 4) - signed coefficient width
• g_OUT_WIDTH : positive (default 24) - signed output width

Ports:

The 5 coefficients are defined in the fir_coef_pkg package (read-only):

c_COEFS = (1, 2, 4, 2, 1)

This is a centred triangular window producing a low-pass FIR filter with DC gain = 10.