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#1 Dec. 18, 2017 14:45:21

jeremy.eggleton@docobo.co.uk
Registered: 2016-02-22
Posts: 1
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Tiwi-BLE bandpass filter for co-operation with LTE modem

(hope you forgive a TiWi-BLE question in a TiWi-SL forum, can't find an appropriate forum)

I'm building a Tiwi-BLE into a product also containing an LTE (aka 4G mobile) module. I've been advised to use a very high Q factor bandpass filter (ie SAW or BAW) in the path between the TiWi-BLE and its chip antenna (in this case an Antenova RUFA) mounted on the same PCB. This is because the LTE bands are much closer in frequency to the Wifi/BT band and there is a high risk of inter-modulation distortion. In fact the LTE IMT-E band used in China is actually abutting the Wifi/BT band.

I see that the TiWi-BLE module contains an internal bandpass filter. No details of it are provided in the datasheet, but would i be right in assuming that it is not selective enough to protect adequately against high-powered LTE transmissions in a neighbouring band?

I don't have the necessary RF knowledge to fully solve the problems of pcb layout needed for such an additional filter, nor how to achieve good matching on both sides of this filter.
What advise /help can you suggest?

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#2 Dec. 19, 2017 14:58:10

SupportEngineer
Registered: 2016-03-11
Posts: 61
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Tiwi-BLE bandpass filter for co-operation with LTE modem

Hello,

We have asked our Hardware Engineering Team for their feedback in regards to your question. Once we have something from them, we will post it on this thread. Due to the holidays, our response might be delayed.

Regards,
Laird/LSR

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