Sierra Wireless WISMO218 - Manual (Page 53)

WA_DEV_W218_PTS_002 Rev 005 Page 53 of 109
Product Technical Specification &
Customer Design Guidelines
Figure 16. Example of MIC Input Differential Connection without LC Filter
The capacitor C1 is highly recommended to eliminate TDMA noise. Note that C1 must be close to the
microphone.
Recommended Components
Component Description/Details Notes
C1 12pF to 33pF needs to be tuned depending on the design
C2, C3, C4 47pF needs to be tuned depending on the design
L1, L2 100nH needs to be tuned depending on the design
Microphone Single-Ended Connection Example
When single-ended connection is used for MIC, MICN is just left open.