Analog Front-End Circuitry in Piezoelectric and Microphone Detection of Photoacoustic Signals

This paper is a review of analog front-end circuitry used in photoacoustic equipment with microphone or piezoelectric detection. A block structure of the front end as well as detailed circuit diagrams of preamplifiers dedicated for piezoelectric sensors and measurement condenser and electret microphones are described. The presented circuits are optimized toward low-noise operation. Practical remarks regarding the design of the remaining analog blocks are also given. The analysis shows that it is possible to design an analog front end for which specifications will be comparable with the best commercial solutions.