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TP2017
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Last seen: 6 months 1 week ago
Joined: 2017-07-15 18:18
Poor Signal

I'm not able to connect when my device is more than 6 feet away. I have a DA14586 with a ZOR Antenna 1.6mm substrate (design from 5.4 AN-B-027). It has a matching circuit that AN-B-027 recommends which I've uploaded (Antenna_cir.pdf). I think I should be getting more range. Is there something else I should be doing?

I'm using some Bluetooth debugging software and I get -85dBm at 6 feet.

Am I supposed to put a setting in OTP_HDR_TRIM_RFIO_CAP_ADDR to help the DA14586 match the antenna/network?

Thanks

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Device: 
PM_Dialog
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Last seen: 2 days 9 hours ago
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Joined: 2018-02-08 11:03
Hi TP2017,

Hi TP2017,

Thanks for your forum post and for your interest in our BLE solutions.

I had a look at the attached schematics and found one small mistake in the antenna matching.

The L2 is in the RFIOp line but it should be connected to the ground. Please take a look at AN-B-054: DA14585/586 Application Hardware Design Guidelines and Figure 3: Antenna matching network ( page 9 ). The L1 inductor ( L2 in your schematic)  shall be placed as close as possible to the DA14586 and connected to ground.

Additionally, what is the package of the DA14586 that you are using? WLCSP or WFN? The value of this shunt inductor depends on the package.

Additionally, the antenna marching is depended on the PCB size. You could measure the impedance of the antenna with network analyzer.

Thanks, PM_Dialog

TP2017
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Last seen: 6 months 1 week ago
Joined: 2017-07-15 18:18
Thanks for the reply. The

Thanks for the reply. The package is QFN40. I'll take a look at the reference AN-B-054. The size of the board is 2.9cm x 9.1cm. I'll look in to measuring the impedance with a network analyzer.

TP2017
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Last seen: 6 months 1 week ago
Joined: 2017-07-15 18:18
I checked Figure 3 of AN-B

I checked Figure 3 of AN-B-054. The circuit looks different than Figure 19 from AN-B-027, "Matching Components, ZOR Antenna, 1.6mm Substrate", which is the antenna we chose. It looks like the ZOR Antenna uses a different matching network than the one in AN-B-054 Figure 3.

I did notice that we should use a 3.9nH inductor vs 3.3 in our current circuit.

TP2017
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Last seen: 6 months 1 week ago
Joined: 2017-07-15 18:18
OK. I looked at the network

OK. I looked at the network matching circuits shown in AN-B-054 (Figure3) and AN-B-027 (Figure 19) more closely. It looks like they are the same except the AN-B-027 doesn't show the shunt inductor (it does mention it). We assumed that the inductor was meant to be in series with the circuit when the diagram in AN-B-054 shows that it is to ground. I'm pretty sure this is the case, if you could take a look and confirm I'd be grateful.

Thanks

PM_Dialog
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Last seen: 2 days 9 hours ago
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Joined: 2018-02-08 11:03
Hi TP2017,

Hi TP2017,

Yes, the AN-B-027 does mention the shunt capacitor but it should be grounded as shown in AN-B-054 (Figure3).

I would also recommend checking the schematics of the DA14586 Pro Daughterboard.

https://www.dialog-semiconductor.com/products/da14585-development-kit-pro

Thanks, PM_Dialog