Interface Circuits for MEMS Microphones
This paper presents an overview of interface circuits for capacitive MEMS microphones. The interface circuits and the building blocks are analyzed in detail, highlighting the most important design issues and trade-offs. Moreover, two design examples are r
- PDF / 1,261,644 Bytes
- 26 Pages / 439.37 x 666.142 pts Page_size
- 88 Downloads / 297 Views
Interface Circuits for MEMS Microphones Piero Malcovati, Marco Grassi, and Andrea Baschirotto
Abstract This paper presents an overview of interface circuits for capacitive MEMS microphones. The interface circuits and the building blocks are analyzed in detail, highlighting the most important design issues and trade-offs. Moreover, two design examples are reported, including circuit details and experimental results. The first example is based on a conventional constant-charge approach, while the second introduces the force-feedback concept. Both examples are implemented in a 0.35-mm CMOS technology and achieve a signal-to-noise and distortion ratio larger than 60 dB with a power consumption of about 1 mW from a 3.3-V power supply.
9.1
Introduction
The first microphone has been invented in 1876. The carbon microphones developed in 1878 were the core of early telephone systems. Ribbon microphones were invented in 1942 for radio-broadcasting. The introduction of a self-biased condenser microphone in 1962, namely the electret condenser microphone, combined high-sensitivity and broad frequency-range features with low-cost. Since then,
P. Malcovati (*) Department of Industrial and Information Engineering, Department of Electrical Engineering, University of Pavia, Via Ferrata 1, Pavia 27100, Italy e-mail: [email protected] M. Grassi Department of Electrical Engineering, University of Pavia, Pavia, Italy e-mail: [email protected] A. Baschirotto Department of Physics, University of Milano Bicocca, Milano, Italy e-mail: [email protected] A.H.M. van Roermund et al. (eds.), Nyquist AD Converters, Sensor Interfaces, 149 and Robustness: Advances in Analog Circuit Design, 2012, DOI 10.1007/978-1-4614-4587-6_9, # Springer Science+Business Media New York 2013
150
P. Malcovati et al.
electret microphones have dominated the market for high-volume applications, with a production of almost one billion parts per year (almost 90% of all microphones produced). The first microphone based on silicon micro-machining (MEMS microphone) was introduced in 1983. Following the trend toward miniaturization in electronic devices, MEMS microphones are gaining market share in consumer applications [1]. The two major areas that are driving the penetration of MEMS microphones are hearing aids and mobile phones. Indeed, MEMS microphones offer several advantages with respect to electret devices: they are smaller in size, compatible with high-temperature automated printed circuit board (PCB) mounting processes, and less susceptible to mechanical shocks. Moreover, MEMS sensors can be integrated together with the CMOS electronics on the same chip or within the same package (micromodule approach [2]), thus reducing area, complexity and costs, while increasing efficiency and reliability [3–14]. MEMS microphones are based on different transduction principles, such as piezoelectric, piezoresistive, and optical detection. However, 80% of the produced MEMS microphones are based on capacitive transduction [15–18], since it achieves hig
Data Loading...
