Modelling of silicon condenser microphones

Abstract

Several models concemmg the senslhvlty of capaclhve pressure sensors have been presented m the past Modellmg of condenser nucrophones, which can be constdered to be a specml type of capacltlve pressure sensor, usually reqmres a more comphcated analysis of the senstttvlly, because they have a strong electnc field m the atr gap It IS found that tbe mechamcal sensltlvlty of condenser rmcrophones ~nth a ctrcular diaphragm, either mth a large uutlal tenston or without any mltml tensloo, Increases mth mcreasmg bias voltage (and the correspondmg static deflection), whereas the mechamcal sensltrvlty of other capacltrve pressure sensors does not depend on the static deflection It is also found that the mechamcal senslttv@ increases wtth mcreasmg input capacitance of a preamphfier In addltlon, the open-clrcmt electrical sensltlvlty and, consequently, the total sensltlvlty too, also Increases mth mcreasmg bras voltage (or stahc deflechon) However, the maxtmum allowable sound pressure at which the diaphragm collapses, an effect that has to be taken into account, decreases Hrlth mcreasmg static deflection in most cases, uhnnately resulting in an optimum value for the bias voltage The model for microphones with a nrcular highly tensloned diaphragm has been venfied successfully for two mlcrophone types *Present address Texas Instruments

Packaging Technology for an Implantable Inner Ear MEMS Microphone

“…During volume adaptation, both diaphragms need to deflect up to 10 times their thickness, where non-linear effects cause mechanical stiffening of the diaphragm. Corrugated diaphragms show longer linear travel than flat diaphragms and hence, should broaden the operating range of the SPEQ system [27]. In case the AV is restricted by the lateral dimension but not by the height, n diaphragm pairs may add up to a stack to achieve the required volume size (Figure 5).…”

Unbiased Charged Circular CMUT Microphone: Lumped-Element Modeling and Performance

“…Numerical modeling studies were carried out as early as 1975 [21], where the static deflection profile of the membrane is considered in electrostatic force calculation in an energy-based context. van der Donk et al [22] proposed the first analytical model in which the electrostatic force and the center displacement of the membrane are interrelated through the electrostatic energy in the microphone and the displacement profile.…”

“…1) The lumped force and displacement variables related through the energy, where force and energy definitions included the ones presented in [22]. 2) The effect of ambient pressure is analytically included.…”

Wideband micromachined capacitive microphones with radio frequency detection

“…Furthermore, achieving a large dynamic range and a high sensitivity can be conflicting goals, since large sound pressures may cause the membrane to collapse under its voltage bias. 12 Beranek 13 derives a small-signal acoustic equivalent circuit model for condenser microphones that can be applied to micromachined microphones of a similar structure. This model, shown in Fig.…”