Silicon Laboratories EFR32, Matching Manual

Page 1: ...er 2 4 GHz operation refer to AN928 EFR32 Layout Design Guide Refer to AN933 EFR32 2 4 GHz Minimal BOM for information on minimizing the bill of materials For information on the matching pro cedure fo...

Page 2: ...aders simply seeking recommended values topologies and RF performance data should skip to Appendix 2 2 4 GHz RF Network Schematics and Technical Data The presented matches are tested with three EFR32...

Page 3: ...GND vias Radio Transciever 2G4RF_IOP 2G4RF_ION RF Frontend PA I Q LNA BALUN RFSENSE Frequency Synthesizer DEMOD AGC IFADC CRC BUFC MOD FRC RAC PGA Figure 2 1 2 4 GHz Front End Configuration The on chi...

Page 4: ...harmonic content in TX mode or the sensitivity in RX mode As part of the design process the goal is to deliver maximum power to a 50 output termina tion e g to a 50 antenna in TX mode In addition prop...

Page 5: ...Bm with FCC compliance It applies a series film type SMD LQP15TN series from Murata inductor and so has a higher cost than the paral lel LC match Moreover it has slightly higher insertion loss The adv...

Page 6: ...utions U S Patent US9780757B1 The matching circuit should show the Zload_opt 23 j11 5 impedance at the input while it is terminated by 50 at its output The general lumped two reactive element matching...

Page 7: ...ccount the parasitics of the discrete components For Silicon Labs reference designs 0402 or 0201 sized surface mount device SMD elements are used With 0201 elements one can expect lower parasitics but...

Page 8: ...st so they are a good compromise at 2 4 GHz in terms of price and Q SMD parasitics are investigated in the ladder two element match employing 0402 SMD elements and a film type inductor Simplified equi...

Page 9: ...pass prototype matching elements series in ductance and parallel capacitance There are three approaches to simulating PCB parasitics lumped element distributed element and EM based Since the trace len...

Page 10: ...ired The gap to the side ground metal are given by the G parameters in the figure The easi est way to make that estimation is to use a grounded coplanar calculator which computes the unit parallel cap...

Page 11: ...onic restrictions of the ETSI and FCC standards However below 10 dBm power levels the ladder two element match is advantageous because it has lower cost and lower insertion loss compared to the ladder...

Page 12: ...ement and four element matches Here the 2G4RF_IOP pin of the EFR32 chip is connected to Port 2 The L0 inductor is connected between Ports 3 and 4 the C0 capacitor be tween Ports 5 and 6 the L1 inducto...

Page 13: ...ement Matching Network Schematic Reference Designator Component Value Tolerance Part Number Manufacturer LH0 1 9 nH 0 05 nH LQP15MN1N9W02 Murata CH0 1 5 pF 0 1 pF GRM1555C1H1R5BA01D Murata Figure 3 10...

Page 14: ...lement match is as expected only proper for the lower 10 dBm power regimes Figure 3 12 Measured S11 and S21 Transfer Characteristic of the Ladder 2 element SMD Match The measured ladder two and four e...

Page 15: ...much larg er even at the highest 20 dBm power level It should be noted that in the spectrum measurements the Spectrum Analyzer is used as a wideband 50 termination With a real antenna the termination...

Page 16: ...amples and are typical Large test sample sensitivity results are only avail able for the 7x7 mm dual band package with a four element lumped element match and are provided in the data sheet Table 4 1...

Page 17: ...wer variation is usually less than 0 5 dB which is less than the chip to chip variation 5 All matches with all EFR32 package versions have less than 0 5 dB power variation across the entire 2 4 GHz ba...

Page 18: ...ure rf 3 http wcalc sourceforge net cgi bin coplanar cgi Copyright 2001 2009 Dan McMahill CGIC copyright 1996 1997 1998 1999 2000 by Thomas Boutell and Boutell Com Inc Permission is granted to use CGI...

Page 19: ...x7 mm 48 pin dual band EFR version at the TX pin Here the optimum impedance is approximately 23 j11 5 At 2 45 GHz the optimum is slightly lower 21 j10 4 Figure C below shows the measured 20 dBm 2 4 GH...

Page 20: ...23 j11 5 Further the optimum impedance does not depend much on the power level At a power level of 10 dBm the optimum termination is only slightly off Zload_opt_10dBm 20 j10 6 for the 7x7 mm dual band...

Page 21: ...ches use GRM1555 type SMD capacitors from Mura ta The ladder two element and four element matches use film type LQP15MN series inductors while the hybrid Tline and parallel LC matches apply low cost m...

Page 22: ...2 Low Second harmonic strongly violates FCC at high power levels 2 element ladder 10 dBm 9 7 42 8 63 5 Low Up to 10 dBm ETSI FCC compliant Hybrid LC Tline C 19 1 51 5 60 Low Middle ETSI FCC Compliant...

Page 23: ...Ladder Four Element Match with the Three EFR Package Versions d T line Match with 7x7 mm Dual Band EFR Version AN930 EFR32 2 4 GHz Matching Guide 2 4 GHz RF Network Schematics and Technical Data sila...

Page 24: ...to 20 dBm power levels 2 The LC parallel minimal BOM match is ETSI and FCC compliant up to 13 dBm power level while the ladder two element lumped element match complies up to 10 dBm 3 Due to the appl...

Page 25: ...o the load impedance that the match should show at the IC side is Zload_opt 23 j11 5 if the antenna side is terminated by 50 A ladder four element match can be designed in two ways using the ladder tw...

Page 26: ...yout Parasitics on page 10 are used The figure below shows the tuned ladder four element match locus and schematic with parasitics The endpoint at the IC side denoted by TP11 in the Smith chart and by...

Page 27: ...Element and PCB Parasitics Table 3 1 Final SMD Values for the Ladder Four Element Match Ladder Four Element Matching Network Schematic refer ence designator Component value Tolerance Part Number Manu...

Page 28: ...unt SMD Capacitor Self Resonating Close to the Second Harmonic The transfer characteristic is shown in Figure 4 1 Effect of a Shunt SMD Capacitor Self Resonating Close to the Second Harmonic on page 2...

Page 29: ...critical harmonics The transmission line is only several mm long which is much shorter than the wavelength at the fundamental frequency and can therefore be modeled as a lumped inductor with some par...

Page 30: ...ents PCB Parasitics are Neglected a b Figure 4 4 Impedances of Differently Tuned Tline Matches on the 2G4RF_IOP Pins AN930 EFR32 2 4 GHz Matching Guide Transmission Line Tline Match for Minimal BOM So...

Page 31: ...s shown in Figure 4 5 EM Simulation of the Tline Match on page 31 part a value is chosen which resonates with C0 close to the fundamental frequency results in low insertion loss and if possible also t...

Page 32: ...d Setting the Tline Length to Get Good Impedance at the 2G4RF_IOP Pin Figure 4 7 Characteristic of the Final EM Tuned Tline Match AN930 EFR32 2 4 GHz Matching Guide Transmission Line Tline Match for M...

Page 33: ...F GRM1555C1H1R2BA01 Murata As shown in part A of the figure below the impedance at the fundamental frequency is 20 j12 which is close to the optimum 23 j11 5 Also second and third harmonic suppression...

Page 34: ...in TX Mode with Different EFR32 Packages The fundamental power second and third harmonic variations across the 2 4 2 48 GHz band are also shown in Appendix 1 According to Appendix 1 PA Optimum Impedan...

Page 35: ...20 dBm Power Level a b Figure 4 12 Measured Spectrum Plots of the Single Band EFR32 Versions with Tline Match at 20 dBm Power State a 7x7 mm BRD4101A b 5x5 mm BRD4111A AN930 EFR32 2 4 GHz Matching Gu...

Page 36: ...ply or express copyright licenses granted hereunder to design or fabricate any integrated circuits The products are not designed or authorized to be used within any Life Support System without the spe...