1.2
www.infineon.com
page 22 of 24
10/08/2021
Infineon UltraHub
User manual
6
Resonance measurements
As the geometry of the final sound channel shifts the resonance of the pure transceiver (compare product briefs
of IM67D131UT and IM70A135UT) the resonance frequencies on the UltraHub shields are shifted compared to
the bare transducer resonances. The following figure shows a comparison of the measured SPL at 10 cm
distance of a type 2 sensing shield (see Figure 24), where only the center transducer (S1) is actuated vs. a
transducer mounted on a thin flex-board.
Figure 24
Layout of type 2 sensing shield
Figure 25
Impact of sound-channel dimension on resonance behavior of a device on sensing shield
compared to a transducer mounted on a slim flex-board
As can be seen from Figure 25 the prolonged sound-channel due to the thickness of the sensing shield is
downshifting both resonances. If the sound-
channel in front of the device’s sound port is further increased
, this
will lead to an additional downshift of both resonances which can be estimated by a transmission line model
1
.
1
Anzinger S. et al. (2019). Acoustic transmission line based modelling of microscaled channels and enclosures. JASA, 145(2), 968-976.
