1-22 (No.RA018)2.4.9.2 GPS CircuitThe RF signal is received by the antenna matched by the matching circuit. The matching circuit consists of L905, C948 and C883.And this signal applied to a high-pass filter. The filter consists of C882, C881, C880, L859 and L858. The filtered RF signal is thenapplied to a SAW filter (L857).The output of the SAW filter is fed into the LNA (IC851). The LNA is enabled by GPS_EXT_LNA_EN (pin H6 of the BT/GPS IC, IC850).The LNA input match comprises of C879, C878 and L856. The LNA output match comprises of C874. And through the Attenuatorcomprised of R857, R856 and R855, the RF signal is further filtered by a second SAW filter (L853).The output of the second SAW filter is passed to pin L2 of the BT/GPS IC. The input match for pin L2 comprises of C867, C866 andL852. The control and data lines for the BT/GPS IC are GPS_PA_EN, BTFM_nSHUTDOWN, GPS_TX and GPS_RX. GPS_TX andGPS_RX are shared with the Bluetooth data line.Frequency configuration for GPS is following:Lo is GPS: 1571.324MHzFig.7 GPS circuit2.5 COMPONENTS DESCRIPTION2.5.1 Main unit (XC1-0331-80, XC1-0360-10)1.8V3.3VOSCILLATOR32.768kHzGPS_TXGPS_RXIC702IC850 BT/GPS ICIC700MPU/DSPHPF Pre-SAW LNAMatchingGPS antennaPost-SAWAttenuatorLNA SupplyLNA EnableTCXO19.2MHzClockBufferLevelConversionGPS IC(IC850)GPS_LNA_IN(L2)GPS_EXT_LNA_EN(H6)VDD_TCXO(G1)TCXO_CLK_LV(F1)BT_HCI_UART_TX(A4)BT_HCI_UART_RX(B5)RTC_CLK(H9)BTFM_nSHUTDOWN(A6)GPS PA EN(G3)VBAT1(A2)TCXO_LDO_IN(H1)VDDSRef. No. Part Name DescriptionIC20 IC ResetIC30 IC Voltage regulator (33SD)IC31 IC Voltage regulator (31BU)IC32 IC Voltage regulator (12BU)IC33 IC DC/DC converter (38M)IC34 IC DC/DC converter (18M)IC35 IC Voltage regulator (33M)IC36 IC Voltage regulator (50C)IC37 IC Voltage regulator (18BT)IC38 IC Voltage regulator (33BT)IC39 IC Voltage regulator (33A)IC60 IC DC/DC converter (130C)IC61 IC Voltage regulator (33C)IC63 IC Voltage regulator (50VCO)IC64 IC Voltage regulator (50R)IC65 IC Voltage regulator (50T)IC70 IC Voltage regulator (53AF)IC80 IC Voltage regulator (30M)IC81 IC Voltage regulator (33OPT)IC82 IC Voltage regulator (50A)IC100 IC PLL ICIC101 IC DC AMPIC102 IC Voltage regulator (DC AMP)IC200 IC PLL ICIC201 IC DC AMPIC300 IC Pre-drive AMP 1IC360 IC DC SW (Antenna SW)IC400 IC APCIC550,551IC DC AMPIC600 IC IF ICIC700 IC Clock bufferIC701 IC DC SW (18M)IC702 IC MPUIC703 IC SDRAMIC704 IC ResetIC705 IC Flash memoryIC706 IC Logic controlIC708 IC I/O controlIC709 IC Motion sensorIC711,712 IC Logic controlIC800 IC LED driverIC801 IC Voltage regulator (50U)IC802 IC Analog SWIC803 IC Level converterIC804~807IC Logic controlIC850 IC GPS/BluetoothIC851 IC GPS LNAIC852,853 IC Level converterIC900 IC A/D converterRef. No. Part Name Description
