(No.RA015<Rev.001>)1-19
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 TX-RX unit (XC1-0341-8X)
1.8V
3.3V
OSCILLATOR
32.768kHz
GPS_TX
GPS_RX
IC702
IC850
BT/GPS IC
IC700
MPU/DSP
HPF
Pre-SAW
LNA
Matching
GPS antenna
Post-SAW
Attenuator
LNA Supply
LNA Enable
TCXO
19.2MHz
Clock
Buffer
LEVEL
SHIFT
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 (200C)
IC61
IC
Voltage regulator (33C)
IC63~65
IC
Voltage regulator (50R/50T/
50VCO)
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 (53AF)
IC200
IC
PLL IC
IC201
IC
DC AMP
IC300
IC
Pre-drive AMP 1
IC360
IC
DC SW (Antenna SW)
IC400,
401
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
IC804,805 IC
Logic control
IC806
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