Advantages of MEMS Microphone | disadvantages of MEMS Microphone
This page covers advantages and disadvantages of MEMS Microphone and its basics. It mentions benefits or advantages of MEMS Microphone and drawbacks or disadvantages of MEMS Microphone.
It works on the same principle as condenser microphone. The condenser microphone consists of two thin plates which form a capacitor. One plate is flexible and the other is rigid. In this microphone type, equal and opposite charge is being applied to the plates. When pressure is applied, capacitance between them varies accordingly. If charge on plates is kept constant when capacitance fluctuates, voltage across it fluctuates.
What is MEMS ?
MEMS is a technique of combining electrical and mechanical components on a single chip. This micro-system will have both sense and control functionalities.
What is MEMS Microphone?
This is widely used microphone type in mobile phones. It works on the same principle as condenser microphone. It is eatched in the silicon. Its diaphragm is about 1 mm square in size.
MEMS microphones are of two types based on its output viz. analog and digital. Analog output is amplified on the same chip. Digital output is PDM encoded or I2S encoded. PDM stands for Pulse Density Modulation where density of bits represent amplitude variations of the sound wave. It requires external clock signal. Refer MEMS Microphone working >> for more information.
The figure depicts Analog MEMS microphone (Part number: ADMP401) with preamplifier from Analog Devices Inc. The part number INMP401 from InvenSense, Inc. is an omnidirectional Microphone with Bottom Port and Analog Output.
Part numbers ICS-43432 and INMP441 are Digital MEMS microphones with I2S format from InvenSense, Inc. Part numbers INMP521, INMP522, INMP621 from InvenSense Inc. support PDM encoding.
Benefits or advantages of MEMS Microphone
Following are the benefits or advantages of MEMS Microphone:
➨It consumes very low power.
➨It is very small in size.
➨It offers high SNR (Signal to Noise Ratio).
➨It offers improved noise cancellation.
➨It can be manufactured using SMT (Surface Mount Technology) and hence it can be integrated with CMOS process.
➨It can withstand high temperature and vibrations.
➨It has flat wideband frequency response.
➨It offers long battery life due to low current consumption.
➨It offers best sensitivity and offers highest reliability and robustness.
Drawbacks or disadvantages of MEMS Microphone
Following are the drawbacks or disadvantages of MEMS Microphone:
➨Very complex procedures are followed during design process.
➨Micro-components are costly compare to macro components. Only mass production will reduce the overall cost of the MEMS devices such as microphone etc.
➨Due to its micro size, significant high power transfer is not possible. Hence preamplifier or op-amp components are needed externally to amplify the signal. Often these components are integrated on the same chip.
➨Proper knowledge and training is required to integrate MEMS based devices such as microphone
➨Polysilicon used in constuction of MEMS devices is a brittle material. RF scientists are exploring MEMS devices with better quality of materials and capacity which can withstand higher power.
Also refer advantages and disadvantages of RF MEMS >> technology.