DSP Builder: Half-Band Filter Using Distributed Arithmetic (DA) & Time-Domain Multiplexing (TDM)
The design example describes an interpolation by two half-band filter with 79 taps (40 none-zero coefficients). Taking advantage of the symmetrical filter coefficients and the concept of time-domain multiplexing (TDM), the design requires only ten multipliers. The multipliers are implemented using distributed arithmetic (DA) where the partial products are stored in the M4K TriMatrix memory blocks. The M4K memory blocks are configured as 128 x 32 dual-port RAMs.
Download the files used in this example:
The use of this design is governed by, and subject to, the terms and conditions of the Altera Hardware Reference Design License Agreement.
Files in the zip download include:
- HBF_DA_Timeshare.mdl—DSP Builder design file implementing the interpolating half-band filter
- init.m—MATLAB script to initialize the sampling time, and simulation time and coefficients. The script also generates the stimuli: chirp and impulse.
- compute_partial_product.m—MATLAB script to calculate the partial products based on the initial filter coefificient values set in init.m. Two sets of partial products are calculated for each coefficient value: one for the MSB segment and the other for the LSB segment of the data. Since the design uses TDM, each LUT stores the partital product for two coefficients.
Figure 1 shows the top-level diagram of the half-band filter design example in DSP Builder.
Figure 1. Half-Band Filter Top-Level Diagram
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Table 1 lists the ports and gives a description for each.
| Table 1. Half-Band Filter Port Listing |
| Port Name |
Type |
Description |
input_data[17:0] |
Input |
18-bit data inputs to complex multiplier unit |
clken |
Input |
Clock enable |
FirResult[18:0] |
Output |
19-bit data output of filter |
Related Links
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