A multichannel analog processing circuit for respiratory sound acquisition applications

A five-channel analog amplifier & filter stage of pulmonary sound data acquisition process has been designed and implemented. The system acquires respiratory sound data through five microphones placed at proper locations on the chest wall along with a flow signal for synchronization. Output is band limited and amplified sound data suitable for further analog-to-digital (AD) conversion. The gain and the high corner frequency are adjustable, the former aiming an optimum use of the AD converter by approximating maximum possible input amplitude and the latter aiming a provision for a possible change to be made in the sampling frequency of the AD converter. In the design, low power consumption, low noise, low cost and low component count have been taken into consideration.