Serial structures –7 multibit serial structure –7, Serial structures, Multibit serial structure – Altera FIR Compiler User Manual

Page 49

Chapter 4: Functional Description

4–7

FIR Compiler

Altera Corporation

Serial Structures

A serial structure trades off area for speed. The filter processes input data one bit at-a-
time per clock cycle. Therefore, serial structures require N clock cycles (where N is the
input data width) to calculate an output. In the Stratix IV, Stratix III, Stratix II, Stratix,
Cyclone III, Cyclone II, and Cyclone device families, using memory blocks for data
storage will result in a significant reduction in area.

Figure 4–4

shows the serial filter block diagram.

Multibit Serial Structure

A multibit serial structure combines several small serial FIR filters in parallel to
generate the FIR result. This structure provides greater throughput than a standard
serial structure while using less area than a fully parallel structure, allowing you to
trade off device area for speed.

Figure 4–5

shows the multibit serial structure.

Figure 4–4. Serial Filter Block Diagram

yout

Bit Array Multiplier

xin

D Q

Serial

Accumulator

Figure 4–5. Multibit Serial Structure

Serial

FIR

Filter

Serial

FIR

Filter

Serial

FIR

Filter

Input

Data

Filtered
Data

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