# Matching Networks for the LimeSDR Mini

**URL:** <https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711>\
**Category:** LimeSDR\
**Created:** [16 September 2017 18:11 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711 "2017-09-16T18:11:09Z")\
**Posts on this page:** 18\
**Page:** 1

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**Author:** ![FFY00](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ffy00/32/1427_2.png) [@FFY00](https://discourse.myriadrf.org/u/FFY00)\
**Post date:** [16 September 2017 18:11 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/1 "2017-09-16T18:11:09Z")

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Can we get some input about the range of the matching networks present in the LimeSDR Mini? I think this should be put out in the blue before we start to get complains about the rf performance in certain bands.

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**Author:** ![9a4db](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/9a4db/32/2675_2.png) [@9a4db](https://discourse.myriadrf.org/u/9a4db)\
**Post date:** [16 September 2017 18:21 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/2 "2017-09-16T18:21:54Z")

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In accordance to presentation target is 10 MHz to 3,5 GHz,  
but final prototype must show real RF performance, when ready.  
I am waiting to see that too…

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**Author:** ![FFY00](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ffy00/32/1427_2.png) [@FFY00](https://discourse.myriadrf.org/u/FFY00)\
**Post date:** [16 September 2017 18:24 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/3 "2017-09-16T18:24:12Z")

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Yes, but I don’t think the matching network will cover that whole spectrum. Just like the normal LimeSDR, the target frequency range included HF but it wasn’t usable due the matching networks.

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**Author:** ![9a4db](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/9a4db/32/2675_2.png) [@9a4db](https://discourse.myriadrf.org/u/9a4db)\
**Post date:** [16 September 2017 18:30 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/4 "2017-09-16T18:30:45Z")

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I am expecting they are going to switch at last two matching networks on one RF connector…

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**Author:** ![FFY00](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ffy00/32/1427_2.png) [@FFY00](https://discourse.myriadrf.org/u/FFY00)\
**Post date:** [16 September 2017 18:36 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/5 "2017-09-16T18:36:15Z")

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The new prototypes only have 2 SMA connectors. The only way it could have 2 different matching networks would be using an rf switch like the HackRF does, I believe. Probably they only have one matching network (for each, rx and tx) tunned to cellular frequencies (GSM, LTE, etc).

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**Author:** ![mzs](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/mzs/32/2678_2.png) [@mzs](https://discourse.myriadrf.org/u/mzs)\
**Post date:** [16 September 2017 20:56 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/6 "2017-09-16T20:56:27Z")

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I’d guess that LimeSDR mini will use RX1\_L for the RX channel, and TX1\_2 for TX channel.

My vague reasoning for this, is that MN17 and MN20 are shown on the RX side of:  
[![](https://www.crowdsupply.com/img/293a/limesdr-mini-render-bothsides_png_open-graph.jpg) ](https://www.crowdsupply.com/img/293a/limesdr-mini-render-bothsides_png_open-graph.jpg)  
And looking at the [schematic for the original LimeSDR](https://github.com/myriadrf/LimeSDR-USB/blob/master/hardware/socket/1v4/Project%20Outputs%20for%20LimeSDR-USB_1v4s_LMS031pad/LimeSDR-USB_1v4s_schematic_r7.PDF) those two components would be associated with RX1\_L  
And also on the initial prototype had RX1\_L and RX2\_L written on the silkscreen:  
[![](https://www.crowdsupply.com/img/6558/limesdr-mini-prototype-top.jpg) ](https://www.crowdsupply.com/img/6558/limesdr-mini-prototype-top.jpg)

MN16 and MN10 would correspond to TX1\_2 looking at the [schematic for the original LimeSDR](https://github.com/myriadrf/LimeSDR-USB/blob/master/hardware/socket/1v4/Project%20Outputs%20for%20LimeSDR-USB_1v4s_LMS031pad/LimeSDR-USB_1v4s_schematic_r7.PDF). And also TX1\_2 and TX2\_2 were shown on the silkscreen for the initial prototype.

So my guess would be the original “default” behaviour for RX1\_L (see the red line on 2nd plot) which stops at 10MHz (well technically 6MHz but it is close enough to 10MHz):  
[https://myriadrf.org/blog/optimising-limesdr-matching-hf/](https://myriadrf.org/blog/optimising-limesdr-matching-hf/)

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**Author:** ![FFY00](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ffy00/32/1427_2.png) [@FFY00](https://discourse.myriadrf.org/u/FFY00)\
**Post date:** [19 September 2017 21:36 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/7 "2017-09-19T21:36:02Z")

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@andrewback

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**Author:** ![mzs](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/mzs/32/2678_2.png) [@mzs](https://discourse.myriadrf.org/u/mzs)\
**Post date:** [20 September 2017 22:14 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/8 "2017-09-20T22:14:16Z")

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Looks like there is a [RF switch to toggle between RF inputs with different matching networks](https://www.crowdsupply.com/lime-micro/limesdr-mini/updates/thanks-common-questions-and-new-external-clock-synchronisation).  
" … the design was also updated with additional RF switching, enabling us to switch a single port between low and high bands."  
I’m going to make a random guess that TX1\_2; TX2\_2 and RX1\_L; RX2\_L are the ports with the RF switches on them.

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**Author:** ![FFY00](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ffy00/32/1427_2.png) [@FFY00](https://discourse.myriadrf.org/u/FFY00)\
**Post date:** [20 September 2017 22:20 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/9 "2017-09-20T22:20:14Z")

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Yes, I read the update. The switch should switch TX\_ H/TX\_L and RX\_H/RX\_L. I don’t understand I you mentioned TX1/TX2 and RX1/RX2. The switch being included, as I previewed, is an good indicator but what I am actually interested is the frequency bands and the performance in the full spectrum.

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**Author:** ![mzs](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/mzs/32/2678_2.png) [@mzs](https://discourse.myriadrf.org/u/mzs)\
**Post date:** [20 September 2017 22:46 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/10 "2017-09-20T22:46:52Z")

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I don’t disagree, but why then would the initial prototype not use those ports ? It makes sense.

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [21 September 2017 08:39 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/11 "2017-09-21T08:39:22Z")

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Measurements will be taken and plots published once the final version boards are back from assembly, which I believe is a few weeks out from now. A number of changes have been made since the prototypes pictured, including to the matching networks, in addition to changing the RF connectors and of course layout etc.

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**Author:** ![hahnpv](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/hahnpv/32/172_2.png) [@hahnpv](https://discourse.myriadrf.org/u/hahnpv)\
**Post date:** [14 February 2018 17:06 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/12 "2018-02-14T17:06:54Z")

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Hi @andrewback, any update on the matching networks / do you have plots available ? Thank you,

philip

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [15 February 2018 08:14 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/13 "2018-02-15T08:14:05Z")

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Will enquire again and see if characterisation of the networks on the production boards has been completed now.

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**Author:** ![cbalint](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@cbalint](https://discourse.myriadrf.org/u/cbalint)\
**Post date:** [18 August 2018 14:41 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/14 "2018-08-18T14:41:03Z")

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News?

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**Author:** ![chibill](https://avatars.discourse-cdn.com/v4/letter/c/ee59a6/32.png) [@chibill](https://discourse.myriadrf.org/u/chibill)\
**Post date:** [11 February 2019 15:34 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/15 "2019-02-11T15:34:37Z")

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Any update? Or will they never be provided?

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**Author:** ![chibill](https://avatars.discourse-cdn.com/v4/letter/c/ee59a6/32.png) [@chibill](https://discourse.myriadrf.org/u/chibill)\
**Post date:** [19 May 2019 23:56 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/16 "2019-05-19T23:56:26Z")

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Bumping this again to bring up the fact that will still have not received an answer.

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**Author:** ![chibill](https://avatars.discourse-cdn.com/v4/letter/c/ee59a6/32.png) [@chibill](https://discourse.myriadrf.org/u/chibill)\
**Post date:** [2 August 2019 12:34 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/17 "2019-08-02T12:34:08Z")

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Still waiting for answers from Lime.

My guess is that we will never get these answers,

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**Author:** ![jakub](https://avatars.discourse-cdn.com/v4/letter/j/ecb155/32.png) [@jakub](https://discourse.myriadrf.org/u/jakub)\
**Post date:** [10 April 2024 09:35 UTC](https://discourse.myriadrf.org/t/matching-networks-for-the-limesdr-mini/1711/18 "2024-04-10T09:35:47Z")

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Hi, please, I am interested in this topic. Are the results available?  
Thanks.