Active Filtering in Beamforming Circuit: Design, Calculation and Simulation

This paper describes and validates an electronic circuit designed to synchronize the phase shift of two analog signals (e.g. two audio signals) using an adaptive active all-pass filter. In the presented application, the adaptive feature means that the system is reading the output, interpreting the result and applying a certain value of the lag element, in our case a low- pass filter. This process is known as audio beamforming because a microphone module is being used to capture the signal and then later to process it in the developed application. The theoretical part is presenting the state of art and the design of the main circuit based on the theoretical formulas and calculation. The simulation part is presenting different environments like LTSpice, Kicad & Labview to get a firs estimation over the outputs. To measure the real values, a test board was developed to prove the functionality of the circuit. Measurements have been performed using Analog Discovery centralized in a database which was used to determine the best configuration of the beamforming circuit to synchronize the two analog audio signals. Besides the identified application in the area of noise cancelling, new potential use cases have been identified in the area of telecom and mobile networks, simple IC synchronizing application or dynamic filtering.