sensors Article On the Design of an Energy Efficient Digital IIR A-Weighting Filter Using Approximate Multiplication Ratko Pilipovi´c 1 , Vladimir Risojevi´c 2 and Patricio Buli´c 1,* 1 Faculty of Computer and Information Science, University of Ljubljana, 1000 Ljubljana, Slovenia;
[email protected] 2 Faculty of Electrical Engineering, University of Banja Luka, 78000 Banja Luka, Bosnia and Herzegovina;
[email protected] * Correspondence:
[email protected] Abstract: This paper presents a new A-weighting filter’s design and explores the potential of using approximate multiplication for low-power digital A-weighting filter implementation. It presents a thorough analysis of the effects of approximate multiplication, coefficient quantization, the order of first-order sections in the filter’s cascade, and zero-pole pairings on the frequency response of the digital A-weighting filter. The proposed A-weighting filter was implemented as a sixth-order IIR filter using approximate odd radix-4 multipliers. The proposed filter was synthesized (Verilog to GDS) using the Nangate45 cell library, and MATLAB simulations were performed to verify the designed filter’s magnitude response and performance. Synthesis results indicate that the proposed design achieves nearly 70% reduction in energy (power-delay product) with a negligible deviation of the frequency response from the floating-point implementation. Experiments on acoustic noise suggest that the proposed digital A-weighting filter can be deployed in environmental noise measurement applications without any notable performance degradation. Keywords: band-pass digital filters; A-weighting filter; approximate computing; approximate filter; noise sensing Citation: Pilipovi´c,R.; Risojevi´c,V.; Buli´c,P.