An Improved VLSI Design of the ALU Based FIR Filter for Biomedical Image Filtering Application
Authors: Arulkumar M. , Chandrasekaran M. 
Published: August 2020

Aim::

FIR filter is the most widely used device in DSP applications, which is also applicable to integrate
with image processing approaches. The ALU based FIR structure is applicable for various devices to increase
the performance. The ALU design operation includes accumulation, subtraction, shifting, multiplication
and filtering. Existing methods are designed with various multipliers like Wallace tree multiplier, DADDA multiplier,
Vedic multiplier and adders like carry select adder, and carry look-ahead adder.

Objective::

The main objective is to reduce the area, delay and power factors since optimum VLSI circuit is employed
in this paper. By these adders and multipliers, operations are independently enabling main operations in
DSP. The FIR filter is designed using a MAC unit with clock regenerative comparators. Introduction: In the
field of the VLSI industry, the low power, reduced time, and area-efficient designs are mostly preferred for various
applications. Adders and multipliers play a vital role in VLSI circuit designs. The recent electronics industry
uses a digital filter for various real-time applications. This utilizes Finite Impulse Response (FIR) and Infinite
Impulse Response (IIR) filters, here the FIR filter is most stable than IIR filter. This FIR filter indicates the
impulse signal into finite form and it is used mainly in DSP processors for getting high-speed. In these two
ALU and FIR circuits, the adders and multiplier block’s usage is increased, it consumes much power.

Method::

The proposed research work uses the clock-gating technique for reducing power consumption. Here
the latch-based clock gating technique provides an efficient result. XOR-based logic circuit reduces the design
complexity and utilizes the less area. Carry save accumulator is a digital adder used for addition. It provides the
two set of output, which is partial sum and carry output. The ripple carry adder uses a full adder circuit for its
operation. It propagates the carry value in the last bit. In addition, the combination of CSA and RCA utilizes
less area, high speed and provides the better throughput. In multiplier block, the booth multiplier algorithm is
used with XOR-based logic. Here this proposed FIR filter is designed for performing image filtration of retina
image. This process improves the better visualization approach inthe medical field.

Results::

Thus, the proposed ALU based FIR filter with a latch-based clock gating technique is designed and analyzed
with various parameters. Here the modified adders and multipliers are proposed for the efficiency of the
system. The modified carry save adder is proposed with combining ripple carry adder logic for improving the
adders’ performance. The enhanced booth multiplier is designed using add and shift method for reducing the
numberof stages to calculate the result. This process is applied to perform image processing of the retina image.
After designing the ALU based FIR filter structure in the VLSI environment, the image is loaded on the MATLAB
as the .png format, then it is converted into a hex file, which is read from the Xilinx to perform filtering
the process. Then the ‘dataout’ is converted into a binary file to obtain the result of the filtering process. The enhanced
booth multiplier reduces the delay by reducing the number of stages to calculate the result. Here the
clock gating technique is proposed with the latch-based design for reducing the dynamic and clock power consumption.
The number of adder’s circuit in both ALU and FIR circuits is less since it improves the overall efficiency
of the system.

Conclusion::

Thus, the proposed methodology concluded that the design and analysis of ALU based FIR filter
for medical image processing give the efficient result on the way of achieving the factors such as power (Static
& amp; Dynamic), Delay (Path delay) area utilization, MSE and PSNR. Here the image processing of FIR results
to MSE and PSNR values, which obtained a better result than the existing VLSI based image processing
works. The latch-based clock gating circuit is connected with the proposed circuit, based on the gated clock signal,
it optimizes the gated circuit of the whole design since it also reduces the error and provides the efficient
power report. This proposed VLSI model is simulated using Xilinx ISE 14.5 and Modelsim synthesizes it; here
with the help of MATLAB, with the adaptation of the 2018a tool, the image filtering was done.