1-22 (No.RA018<Rev.002>)
2.4.9.2 GPS Circuit
The 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 then
applied 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 Attenuator
comprised 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 and
L852. The control and data lines for the BT/GPS IC are GPS_PA_EN, BTFM_nSHUTDOWN, GPS_TX and GPS_RX. GPS_TX and
GPS_RX are shared with the Bluetooth data line.
Frequency configuration for GPS is following:
Lo is GPS: 1571.324MHz
Fig.7 GPS circuit
2.5 COMPONENTS DESCRIPTION
2.5.1 Main unit (XC1-0331-80, XC1-0360-10)
1.8V
3.3V
OSCILLATOR
32.768kHz
GPS_TX
GPS_RX
IC702
IC850 BT/GPS IC
IC700
MPU/DSP
HPF
Pre-SAW LNAMatching
GPS antenna
Post-SAWAttenuator
LNA Supply
LNA Enable
TCXO
19.2MHz
Clock
Buffer
Level
Conversion
GPS 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)
VDDS
Ref. No. Part Name Description
IC20 IC Reset
IC30 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 IC
IC101 IC DC AMP
IC102 IC Voltage regulator (DC AMP)
IC200 IC PLL IC
IC201 IC DC AMP
IC300 IC Pre-drive AMP 1
IC360 IC DC SW (Antenna SW)
IC400 IC APC
IC550,
551
IC DC AMP
IC600 IC IF IC
IC700 IC Clock buffer
IC701 IC DC SW (18M)
IC702 IC MPU
IC703 IC SDRAM
IC704 IC Reset
IC705 IC Flash memory
IC706 IC Logic control
IC708 IC I/O control
IC709 IC Motion sensor
IC711,712 IC Logic control
IC800 IC LED driver
IC801 IC Voltage regulator (50U)
IC802 IC Analog SW
IC803 IC Level converter
IC804~
807
IC Logic control
IC850 IC GPS/Bluetooth
IC851 IC GPS LNA
IC852,853 IC Level converter
IC900 IC A/D converter
Ref. No. Part Name Description
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