• State
  • Locked Locked
  • Replies 9 replies
  • Subscribers 16 subscribers
  • Views 949 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC112x - with LNA and SAW

RingMain
Prodigy 80 points
Other Parts Discussed in Thread: CC1020, CC1120

Hi. Where in the reference schematic (CC112xEM_420_470) would I insert a  SAW and LNA, both with 50ohm in/out?

Thanks

 

  • 0
    TI__Mastermind 20210 points

    Can you give detail of what you intend to do?

    Thanks.

  • 0 in reply to FI
    Prodigy 80 points
    Hi. I just want to increase RX sensitivity, as I’ve done previously with CC1020, where I inserted a SAW followed by LNA after the antenna switch. But CC112x reference design has a different arrangement for switching between TX and RX and it’s not clear to me where I can insert the SAW and LNA, both of which are 50 ohm in/out, without affecting circuit’s impedance.
  • 0 in reply to RingMain
    TI__Mastermind 20210 points

    this should give an idea of how to integrate your particular solution. You can place the SAW filter after the LNA/PA

    http://www.ti.com/tool/cc112xsky65367em-rd

    if you have a specific LNA/PA and SAW in mind let us know and we can suggest a configuration.

  • 0 in reply to FI
    Prodigy 80 points

    Thank you Farrukh. I am familiar with the link you sent me, but taking that approach (which is for 169MHz application) would require component value changes for my 420-470MHz application, plus an antenna switch which I'm hoping to avoid with CC112x. Can I send you a schematic?

  • 0 in reply to RingMain
    TI__Mastermind 20210 points

    sure. Send the schematic and i will get back to you on this.

  • 0 in reply to FI
    Prodigy 80 points

    Thanks. The attached schematic is from TI's reference design (CC112xEM_420_470). I've highlighted capacitor C181 which taps off RX signals at point A. Ideally (unless you suggest otherwise) I'd like to remove C181 pin 2 from point A and instead connect my LNA/SAW circuit to point A. Then C181 would be connected to the output of my LNA/SAW circuit. However, for this scheme to work the impedance at point A needs to be 50 ohms as my LNA/SAW circuit has 50 ohms in/out. Any thoughts? Alternative solutions would involve an antenna switch, and component value changes, both of which I'd like to avoid if I can.

    Thanks

  • 0 in reply to RingMain
    TI__Mastermind 20210 points

    Ideally you could place the LNA where you have suggested and SAW instead of L173, C177, L174, and C175 to knock down harmonics.
    I believe the impedance at point A is 50ohm but i will verify this with simulation and get back to you.

  • 0 in reply to FI
    Prodigy 80 points

    Thank you for the speedy replies.

    Replacing the filter components with the SAW is a good idea, although the SAW then needs to handle the required TX power from CC112x.

    It would be great to know if point A is already at 50 ohms.

    Thanks.

  • 0 in reply to RingMain
    TI__Mastermind 20210 points

    I have attached the S11 file measured at point A by lifting L173 and setting the CC1120 in RX mode.
    Now this includes the effect of L172 and C176 portions of the network. This will help you with impedance calculations.


    Also, for your particular application, you may have to tweak the balun to have impedance looking into the LNA/SAW to be 50ohm. Please see this AN068 for reference.

    1440.CC1120_S11_RX_MODE.txt 
    !Agilent Technologies,E5071B,MY42301378,A.09.10
!Date: Mon Jan 27 10:56:58 2014
!Data & Calibration Information:
!Freq	S11:SOLT2(ON)
# Hz S RI R 50
1000000	1.007842e+000	-3.018761e-002
8495000	9.794376e-001	-2.223932e-001
15990000	8.988328e-001	-3.995303e-001
23485000	7.813489e-001	-5.482725e-001
30980000	6.372680e-001	-6.600929e-001
38475000	4.786313e-001	-7.347236e-001
45970000	3.257477e-001	-7.691408e-001
53465000	1.814904e-001	-7.804286e-001
60960000	4.629389e-002	-7.650353e-001
68455000	-7.779147e-002	-7.319126e-001
75950000	-1.870427e-001	-6.846595e-001
83445000	-2.841654e-001	-6.242324e-001
90940000	-3.661583e-001	-5.559456e-001
98435000	-4.378267e-001	-4.793573e-001
105930000	-4.990920e-001	-3.939862e-001
113425000	-5.445066e-001	-3.008449e-001
120920000	-5.775430e-001	-2.054364e-001
128415000	-5.964366e-001	-1.110044e-001
135910000	-6.036824e-001	-1.833236e-002
143405000	-6.011330e-001	7.295605e-002
150900000	-5.881021e-001	1.617695e-001
158395000	-5.647467e-001	2.470435e-001
165890000	-5.312455e-001	3.253840e-001
173385000	-4.884129e-001	4.004427e-001
180880000	-4.357656e-001	4.708021e-001
188375000	-3.759391e-001	5.379769e-001
195870000	-3.104287e-001	5.888780e-001
203365000	-2.388480e-001	6.247313e-001
210860000	-1.618439e-001	6.536637e-001
218355000	-8.675141e-002	6.723324e-001
225850000	-8.974189e-003	6.831244e-001
233345000	6.843458e-002	6.833537e-001
240840000	1.440602e-001	6.767645e-001
248335000	2.160658e-001	6.617604e-001
255830000	2.840896e-001	6.390865e-001
263325000	3.460645e-001	6.075020e-001
270820000	4.050573e-001	5.677713e-001
278315000	4.616769e-001	5.222914e-001
285810000	5.125314e-001	4.729287e-001
293305000	5.547675e-001	4.207547e-001
300800000	5.888801e-001	3.626216e-001
308295000	6.159181e-001	2.985376e-001
315790000	6.379865e-001	2.310715e-001
323285000	6.502531e-001	1.620659e-001
330780000	6.542675e-001	9.172249e-002
338275000	6.484505e-001	2.099162e-002
345770000	6.307869e-001	-4.778258e-002
353265000	6.027022e-001	-1.124444e-001
360760000	5.622040e-001	-1.710058e-001
368255000	5.113984e-001	-2.171823e-001
375750000	4.615063e-001	-2.541952e-001
383245000	4.142667e-001	-2.941241e-001
390740000	3.566298e-001	-3.391435e-001
398235000	2.842529e-001	-3.740269e-001
405730000	2.010064e-001	-3.909288e-001
413225000	1.117949e-001	-3.827220e-001
420720000	2.647961e-002	-3.516100e-001
428215000	-4.879086e-002	-3.025658e-001
435710000	-1.081839e-001	-2.398557e-001
443205000	-1.495600e-001	-1.662975e-001
450700000	-1.730113e-001	-8.723126e-002
458195000	-1.766439e-001	-6.553512e-003
465690000	-1.621899e-001	6.961996e-002
473185000	-1.304597e-001	1.359967e-001
480680000	-8.741305e-002	1.909126e-001
488175000	-3.622605e-002	2.328851e-001
495670000	1.762499e-002	2.635397e-001
503165000	7.180017e-002	2.823422e-001
510660000	1.242918e-001	2.913006e-001
518155000	1.762402e-001	2.876118e-001
525650000	2.263408e-001	2.780850e-001
533145000	2.721791e-001	2.655717e-001
540640000	3.101192e-001	2.493837e-001
548135000	3.388125e-001	2.276192e-001
555630000	3.631035e-001	2.028248e-001
563125000	3.883331e-001	1.795810e-001
570620000	4.144656e-001	1.558527e-001
578115000	4.384317e-001	1.285384e-001
585610000	4.579000e-001	9.840369e-002
593105000	4.722568e-001	6.533107e-002
600600000	4.832729e-001	3.196577e-002
608095000	4.897862e-001	-3.481691e-003
615590000	4.909019e-001	-3.666215e-002
623085000	4.859049e-001	-7.072732e-002
630580000	4.773446e-001	-1.044817e-001
638075000	4.648002e-001	-1.357526e-001
645570000	4.516420e-001	-1.658454e-001
653065000	4.319958e-001	-1.890366e-001
660560000	4.040327e-001	-2.077566e-001
668055000	3.669744e-001	-2.246698e-001
675550000	3.264447e-001	-2.377809e-001
683045000	2.845800e-001	-2.387352e-001
690540000	2.407875e-001	-2.214204e-001
698035000	2.009844e-001	-1.861636e-001
705530000	1.766607e-001	-1.340979e-001
713025000	1.800154e-001	-7.272292e-002
720520000	2.174306e-001	-1.823407e-002
728015000	2.822662e-001	1.373893e-002
735510000	3.560008e-001	1.578245e-002
743005000	4.224425e-001	-8.951018e-003
750500000	4.737895e-001	-4.877276e-002
757995000	5.086948e-001	-9.584210e-002
765490000	5.306559e-001	-1.466346e-001
772985000	5.412595e-001	-1.911618e-001
780480000	5.417446e-001	-2.317316e-001
787975000	5.362782e-001	-2.685262e-001
795470000	5.278398e-001	-3.015678e-001
802965000	5.157453e-001	-3.331783e-001
810460000	5.018201e-001	-3.647934e-001
817955000	4.873858e-001	-3.914984e-001
825450000	4.713382e-001	-4.159916e-001
832945000	4.552017e-001	-4.395907e-001
840440000	4.391339e-001	-4.598970e-001
847935000	4.229283e-001	-4.793702e-001
855430000	4.073442e-001	-4.960679e-001
862925000	3.887538e-001	-5.093563e-001
870420000	3.716368e-001	-5.212362e-001
877915000	3.550534e-001	-5.329529e-001
885410000	3.540432e-001	-5.532765e-001
892905000	3.389667e-001	-5.627825e-001
900400000	3.222886e-001	-5.741426e-001
907895000	3.047238e-001	-5.835895e-001
915390000	2.862568e-001	-5.930636e-001
922885000	2.687077e-001	-6.009395e-001
930380000	2.519209e-001	-6.083554e-001
937875000	2.344602e-001	-6.124959e-001
945370000	2.150655e-001	-6.154478e-001
952865000	1.973219e-001	-6.196401e-001
960360000	1.800217e-001	-6.251374e-001
967855000	1.682732e-001	-6.291853e-001
975350000	1.584804e-001	-6.329920e-001
982845000	1.459393e-001	-6.343707e-001
990340000	1.321483e-001	-6.364620e-001
997835000	1.166278e-001	-6.390403e-001
1005330000	1.019080e-001	-6.408590e-001
1012825000	8.942946e-002	-6.427868e-001
1020320000	7.727289e-002	-6.421950e-001
1027815000	6.467434e-002	-6.430131e-001
1035310000	5.312757e-002	-6.433391e-001
1042805000	4.240543e-002	-6.433661e-001
1050300000	3.297438e-002	-6.415625e-001
1057795000	2.285930e-002	-6.410707e-001
1065290000	1.344756e-002	-6.398472e-001
1072785000	4.238346e-003	-6.395630e-001
1080280000	-7.409365e-003	-6.392074e-001
1087775000	-1.795186e-002	-6.374767e-001
1095270000	-3.027717e-002	-6.383291e-001
1102765000	-4.156180e-002	-6.401361e-001
1110260000	-5.277962e-002	-6.408040e-001
1117755000	-6.194143e-002	-6.397862e-001
1125250000	-6.989401e-002	-6.400067e-001
1132745000	-7.713530e-002	-6.414013e-001
1140240000	-8.385048e-002	-6.425828e-001
1147735000	-8.866252e-002	-6.423241e-001
1155230000	-9.586628e-002	-6.440939e-001
1162725000	-1.052673e-001	-6.455920e-001
1170220000	-1.136002e-001	-6.457345e-001
1177715000	-1.238168e-001	-6.453423e-001
1185210000	-1.341564e-001	-6.459491e-001
1192705000	-1.464338e-001	-6.483331e-001
1200200000	-1.584321e-001	-6.566872e-001
1207695000	-1.644602e-001	-6.607217e-001
1215190000	-1.714919e-001	-6.608551e-001
1222685000	-1.832431e-001	-6.588636e-001
1230180000	-1.984478e-001	-6.567244e-001
1237675000	-2.123578e-001	-6.588195e-001
1245170000	-2.245838e-001	-6.609159e-001
1252665000	-2.368790e-001	-6.611867e-001
1260160000	-2.472521e-001	-6.620909e-001
1267655000	-2.592491e-001	-6.621102e-001
1275150000	-2.726080e-001	-6.599914e-001
1282645000	-2.845990e-001	-6.574910e-001
1290140000	-2.945408e-001	-6.571488e-001
1297635000	-3.068871e-001	-6.539222e-001
1305130000	-3.200983e-001	-6.701902e-001
1312625000	-3.350713e-001	-6.645423e-001
1320120000	-3.505509e-001	-6.585349e-001
1327615000	-3.635382e-001	-6.515324e-001
1335110000	-3.772109e-001	-6.444973e-001
1342605000	-3.899686e-001	-6.390850e-001
1350100000	-4.020178e-001	-6.353947e-001
1357595000	-4.143854e-001	-6.322563e-001
1365090000	-4.276603e-001	-6.284030e-001
1372585000	-4.411410e-001	-6.237909e-001
1380080000	-4.526844e-001	-6.185533e-001
1387575000	-4.639767e-001	-6.113834e-001
1395070000	-4.739066e-001	-6.030308e-001
1402565000	-4.843223e-001	-5.914376e-001
1410060000	-4.949272e-001	-5.825582e-001
1417555000	-5.063346e-001	-5.719366e-001
1425050000	-5.164178e-001	-5.630565e-001
1432545000	-5.282720e-001	-5.541469e-001
1440040000	-5.394350e-001	-5.468517e-001
1447535000	-5.484637e-001	-5.388999e-001
1455030000	-5.595073e-001	-5.315796e-001
1462525000	-5.690326e-001	-5.226736e-001
1470020000	-5.780341e-001	-5.146892e-001
1477515000	-5.869369e-001	-5.063125e-001
1485010000	-5.945885e-001	-4.966533e-001
1492505000	-6.029553e-001	-4.878864e-001
1500000000	-6.134860e-001	-4.773476e-001