OnQ Blog

Product Guide: Automotive RF Filters for GNSS Applications

May 1, 2021

Qualcomm products mentioned within this post are offered by Qualcomm Technologies, Inc. and/or its subsidiaries.

Automotive grade SAW, TC-SAW and BAW filters from Qualcomm Technologies are designed for challenging requirements. With highly robust packaging footprints down to 1.1 mm x 0.9 mm, they can easily be incorporated into the smallest automotive applications. RF filters are available in two package technologies:

CSSP is a product of Qualcomm Technologies, Inc. and/or its subsidiaries Technical data subject to change. Filter specification must be taken from the respective product Data Sheet.

Standard single frequency L1 Band GNSS

Standard single frequency L1-Band GNSS are being used for convenience Car-Navigation as well as positioning systems (eg. E-call). The requirements for L1-Band GNSS filters are:

  • Low Insertion Attenuation (IA) and amplitude ripple for better sensitivity (low noise figure)
  • High Attenuation at the LTE bands to mitigate interferences disturbing the GNSS signal reception
  • The AEC-Q200 grade (G) requirement depends on the application (Antenna or Dashboard)

Example of a standard single frequency L1 Band GNSS block diagram:

Technical data subject to change. Filter specification must be taken from the respective product Data Sheet.

* AEC-Q200 grade 1 (-40 to +125°C)

For more details about the Diplexers, Passband and Bandstop filters portfolio please contact your local sales partner or refer to the SAW Device Selection Table AE.

 

High precision multifrequency GNSS ADAS

Advanced Driver Assistance Systems (ADAS) are designed to help the driver make decisions or, in the case of autonomous vehicles, take decisions on their own. Further, ADAS generates warning signals for critical events, such as collision avoidance, speed control, braking, blind spot detection and park assist.

ADAS is deployed in combination with high precision multifrequency GNSS, used to generate data required for precise location-based warnings (e.g. high speed warning in advance of a tight curve) and/or relevant driving commands.

An enabling component of these high precision GNSS modules are the RF filters. It is imperative that an appropriate filter is selected. The requirements for high precision ADAS/GNSS filters are:

  • The Group Delay Ripple (GDR) requirement is very strict. The target is around 5ns for the specific GNSS sub-bands in order to be able to achieve the precise positioning requirements → avoiding collisions
  • Low Insertion Attenuation (IA) and amplitude ripple for better sensitivity (low noise figure)
  • High Attenuation at the LTE bands to mitigate interferences disturbing the GNSS signal reception
  • The AEC-Q200 grade (G) requirement depends on the application (Antenna or Dashboard)
Technical data subject to change. Filter specification must be taken from the respective product Data Sheet.

Please contact your local sales partner for other configurations.

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