SIM868_RF_Design_Application Note

SIM868_RF_Design_Application Note_V1.00 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision Document Title: SIM868_RF_Design_Application Note_V1.00 Version: Date: Status: V1.00 2016-09-13 Released SIM868_RF Design Guide_V1.00 Document Control ID: General Notes SIMCom offers this information as a service to its customers, to support application and engineering efforts that use the products designed by SIMCom. The information provided is based upon requirements specifically provided to SIMCom by the customers. SIMCom has not undertaken any independent search for additional relevant information, including any information that may be in the customer’s possession. Furthermore, system validation of this product designed by SIMCom within a larger electronic system remains the responsibility of the customer or the customer’s system integrator. All specifications supplied herein are subject to change. Copyright This document contains proprietary technical information which is the property of SIMCom Limited., copying of this document and giving it to others and the using or communication of the contents thereof, are forbidden without express authority. Offenders are liable to the payment of damages. All rights reserved in the event of grant of a patent or the registration of a utility model or design. All specification supplied herein are subject to change without notice at any time. Copyright © Shanghai SIMCom Wireless Solutions Ltd. 2008 SIM868_RF_Design_Application Note_V1.00 2016-09-13 2 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision Contents Contents ..................................................................................................................................................................... 3 Version history .......................................................................................................................................................... 4 1 Introduction ......................................................................................................................................................... 5 2 SIM868 RF Interface overview .......................................................................................................................... 5 3 Circuit Design ..................................................................................................................................................... 5 3.1 GSM antenna interface ................................................................................................................................. 5 3.2 BT antenna interface ..................................................................................................................................... 7 3.3 GNSS antenna interface................................................................................................................................ 7 3.4 Power supply circuit design .......................................................................................................................... 8 3.5 Noise Suppression Consideration ................................................................................................................. 9 4 Components placement and PCB layout ............................................................................................................11 4.1 Antenna part ................................................................................................................................................11 4.2 Two-layer PCB RF trace design .................................................................................................................. 12 4.2.1 1.0mm Two-layer PCB ...................................................................................................................... 12 4.2.2 1.6mm Two-layer PCB ...................................................................................................................... 13 4.3 Power supply part ....................................................................................................................................... 14 SIM868_RF_Design_Application Note_V1.00 2016-09-13 3 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision Version history Version Description of change 1.00 Initial version Date 2016-09-13 Author Chen Xiaoxu SIM868_RF_Design_Application Note_V1.00 2016-09-13 4 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision 1 Introduction This document describes the SIM868 module RF antenna interface and recommended antenna performance specifications. In order to get better RF performance, the customer should follow antenna design guides in the document. 2 SIM868 RF Interface overview Designed for global market, SIM868 is integrated with a high performance GSM/GPRS engine , a BT engine and a GNSS engine. The following figure shows a functional diagram of SIM868: Figure 1: SIM868 functional diagram 3 Circuit Design 3.1 GSM antenna interface The following is the recommended GSM antenna circuit design. SIM868_RF_Design_Application Note_V1.00 2016-09-12 5 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision Module GND (Pin31) GSM_ANT (Pin32) GND (Pin33) R101 GSM Antenna C101 C102 D101 Figure 2: GSM antenna matching circuit without RF connector In above figure, the components R101, C101 and C102 are used for antenna matching, the value of components can only be got after the antenna tuning, usually, they are provided by antenna vendor. By default, the R101 is 0Ω resistors, and the C101, C102 are reserved for tuning. To get better ESD performance, a bidirectional TVS component D101 is placed near by the antenna port, which is used for ESD protection, the recommended part numbers of the TVS are listed in the following table: Table 1: The recommended TVS part Part Type LXES03AAA1-154 LXES15AAA1-153 Vendor Murata Murata Package Size 0201 0402 SIM868_RF_Design_Application Note_V1.00 2016-09-12 6 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision 3.2 BT antenna interface The following figure is the recommended BT antenna interface circuit design. Module GND (PIN19) BT_ANT (PIN20) GND (PIN21) 1.2nH C110 C108 0.5pF 2.7nH C111 L101 4.3nH C114 1.8pF C109 1.2pF C113 1.2pF C112 1.5pF L102 4.7nH BT Antenna 0R C115 C106 C107 Module output impedance matching. LC filter, close to module, and it is must if the terminal should PASS SIG spe BT Antenna impedance matching Figure 3: BT antenna matching circuit The C108 and C110 are used for RF Matching，The default values of these two components are shown in Figure 3, but must be tuned on different PCB. The LC filter is mandatory for SIG spec. and these components should be placed close to the module as can as possible. The default values of these components are shown in Figure 3, but must be tuned on different PCB. The components C106, C115, C107 are for antenna impedance matching. These components should be placed as close as possible to the antenna port. By default, the C115 is 0Ω resistors, and the C106, C107 are reserved for tuning 3.3 GNSS antenna interface For GNSS antenna interface design, there are two normal options: passive antenna and active antenna. The customer can choose passive antenna, if the path loss from the GNSS antenna to module’s GPS_ANT pin is not much. If the GNSS antenna is far away from the module’s GPS_ANT pin, then an active antenna should be a good choice. For both passive and active antenna, the recommended circuits are shown as below. MODULE GPS_ANT (PIN68) GND (PIN67) BPF Matching circuit R101 C101 C102 GNSS Passive Antenna Figure 1: GNSS passive antenna matching circuit SIM868_RF_Design_Application Note_V1.00 2016-09-12 7 SIMCOM CONFIDENTIAL FILE

Smart Machine Smart Decision MODULE VCC_ANT R102 10Ω L101 27nH BPF GPS_ANT (PIN68) GND (PIN67) Matching circuit R101 C101 C102 GNSS Active Antenna Figure 5: GNSS active antenna matching circuit In above figure, the components R101, C101 and C102 are used for antenna matching, the components’ value only can be got after the antenna tuning. For default, R101 is 0Ω, C101 and C102 are not mounted. The component R102 is used for current limiting under the situation that the active antenna was shorted. The component L101 is a RF choke inductor, to avoid the RF signal loss, and usually, the value of L101 is no less than 27nH. The component BPF is a SAW filter, which is used for out of band noise signal suppression. The recommended part numbers of the BPF are listed in Table 2: Table 2: The recommended GNSS BPF parts Package Size 1.35*1.05 1.4*1.1 1.1*0.9 1.1*0.9 Part Type SAFEB1G57KE0F00 B8313 SAFFB1G56KB0F0A B8813 Vendor Murata Epcos Murata Epcos 3.4 Power supply circuit design In order to suppress noise signal from power supply, a circuit for noise rejection should be added between the power supply and SIM868 GPS_VBAT/VBAT pad, shown as Figure 6. SIM868_RF_Design_Application Note_V1.00 2016-09-12 8 SIMCOM CONFIDENTIAL FILE

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