A High-Performance and Energy-Efficient FIR Adaptive Filter Using Approximate Distributed Arithmetic Circuits

In this paper, a fixed-point finite impulse response adaptive filter is proposed using approximate distributed arithmetic (DA) circuits. In this design, the radix-8 Booth algorithm is used to reduce the number of partial products in the DA architecture, although no multiplication is explicitly performed. In addition, the partial products are approximately generated by truncating the input data with an error compensation. To further reduce hardware costs, an approximate Wallace tree is considered for the accumulation of partial products. As a result, the delay, area, and power consumption of the proposed design are significantly reduced. The application of system identification using a 48-tap bandpass filter and a 103-tap high-pass filter shows that the approximate design achieves a similar accuracy as its accurate counterpart. Compared with the state-of-the-art adaptive filter using bit-level pruning in the adder tree (referred to as the delayed least mean square (DLMS) design), it has a lower steady-state mean squared error and a smaller normalized misalignment. Synthesis results show that the proposed design attains on average a 55% reduction in energy per operation (EPO) and a 3.2x throughput per area compared with an accurate design. Moreover, the proposed design achieves 45%-61% lower EPO compared with the DLMS design. A saccadic system using the proposed approximate adaptive filter based cerebellar model achieves a similar retinal slip as using an accurate filter. These results are promising for the large-scale integration of approximate circuits into high-performance and energy-efficient systems for error-resilient applications.