Kenwood NX-3400 Service Manual page 18

2.3.9.1 Bluetooth Circuit
The Bluetooth/GPS IC (IC351) support Bluetooth 4.0 up to HCI level.
Basic Rate
TX/RX frequency is 2400-2483.5MHz (79ch Hopping, 2402-2480MHz, 1MHz step). Transmitting power is +0dBm (Max.: +4dBm) at
Bluetooth antenna input.
Low Energy
TX/RX frequency is 2400-2483.5MHz (40ch (3 advertising channels: Single carrier, 37data channels: Hopping), 2402-2480MHz,
2MHz step). Transmitting power is +0dBm (Max.: +4dBm) at Bluetooth antenna input.
Common
Bluetooth antenna is made of sheet metal, and connected to the Bluetooth/GPS IC (IC351) through the LC filter (L361).
IC401
MPU/DSP
X401
TCXO
19.2MHz
Frequency configuration for Bluetooth is following:
There are two LO modes: 2X and Offset LO (OSLO). 2X where LO is 2*RF_FREQ (e.g. when transmitting at 2441MHz it is at
4882MHz). OSLO where LO is at (2/3)*RF_FREQ (e.g. when transmitting at 2441MHz it is at 1627.333MHz).
In RX the 2X is always used.
In GFSK TX if power is >10dBm then OSLO is used
In EDR2 TX if power is >-12dBm then OSLO is used
In EDR3 TX if power is >-12dBm then OSLO is used
Otherwise 2X is used for TX as well.
2.3.9.2 GPS Circuit
The RF signal is received by the antenna matched by the matching circuit. The matching circuit consists of L173, C172 on DISPLAY
Unit. And this signal applied to a high-pass filter. The filter consists of C175, C177, C179, L176 and L178 on DISPLAY Unit. The filtered
RF signal is then applied to a LNA Module (A151).
The output of the LNA Module is fed into the SAW Filter (L359) after through the Attenuator comprised of R354, R355 and R356.
The output of the second SAW filter is passed to pin L2 of the GPS IC. The input match for pin L2 comprises of C369, C395 and L353.
The control and data lines for the GPS IC are GPS_PA_EN, BTFM_nSHUTDOWN, GPS_TX and GPS_RX. GPS_TX and GPS_RX
are shared with Bluetooth data line.
Frequency configuration for GPS is following:
Lo is GPS: 1571.324MHz
GPS antenna
C175, C177
C179, L176
C172, L173
L178
Matching
HPF
1-18 (No.RA070<Rev.001>)
IC352
Level
Conversion
BT/GPS
IC353
Level
Conversion
Q401
Clock
Buffer
Fig.8 Bluetooth circuit
LNA Supply
Pre-SAW LNA
Post-SAW
LNA Module
TCXO
19.2MHz
X401
Fig.9 GPS circuit
IC351
L361
LC
Filter
IC
X351
32.768kHz
Clock
IC351
VDD_TCXO(G1)
GPS_EXT_LNA_EN(H6)
GPS IC(IC850)
GPS_LNA_IN(L2)
BT_HCI_UART_TX(A4)
Post-SAW BT_HCI_UART_RX(B5)
BTFM_nSHUTDOWN(A6)
Clock
TCXO_CLK_LV(F1)
Buffer
Q401
Bluetooth
Antenna
VBAT1(A2)
3.2V
TCXO_LDO_IN(H1)
VDDS
1.8V
IC352,
IC353
GPS_TX
Level
GPS_RX
Conversion
GPS PA EN(G3)
OSCILLATOR
RTC_CLK(H9)
32.768kHz
X351
IC401
MPU/DSP