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RF Front End
MC13192EVB Reference Manual, Rev. 1.2
Freescale Semiconductor
3-7
Figure 3-8. Optional Bias Control Schematic
Adding the circuit around Q102 and Q103 stabilizes the bias. R112 should be changed to 22 kOhm. As the
collector current ramps up, the voltage drop across R108 reaches 0.6 V and Q103 turns on. This causes
Q102 to shunt away excess base bias and stabilizes the collector current at 3.7 mA. Slight temperature
dependence is still present due to the temperature drift of the B-E path of Q103. By employing an NTC
resistor as part of R108, this drift can be compensated for. Adding R106 turns off the LNA in TX mode.
Switching the base feed to GPIO1 turns the LNA off in standby and sleep mode. This is accomplished by
removing R112 and adding R119. Because the GPIO1 does not work properly in some test modes, the
default configuration has R112 mounted.
3.6
Reference oscillator
Figure 3-9. Simplified Oscillator Schematic
Q101
MBC13900
2
4
1,
3
C1 28
10pF
Input, 5 0 Ohm
L104
5.6nH
C1 32
100pF
L105
1.5nH
R1 40
220R
C1 05
1.0pF
Output, 50 Ohm
C1 15
10pF
R1 08
150R
VCC_LNA 2-3.6V
Q103
MMBT39 06
Q102
MMBT39 04
R1 06 470K
AntCtrl
R1 07 470K
R1 19 22K
Not Mounted
GPIO1
R1 05 22K
Not Mounted
LNACtrl
R1 12 22K
LNA
Bias control
Biasing options
Содержание FREESCALE MC13192
Страница 1: ...Document Number MC13192EVBRM Rev 1 2 09 2006 MC13192 Evaluation Board Reference Manual...
Страница 8: ...MC13192EVB Reference Manual Rev 1 2 vi Freescale Semiconductor...
Страница 10: ...Safety Information MC13192EVB Reference Manual Rev 1 2 1 2 Freescale Semiconductor...
Страница 18: ...System Overview MC13192EVB Reference Manual Rev 1 2 2 8 Freescale Semiconductor...
Страница 32: ...RF Front End MC13192EVB Reference Manual Rev 1 2 3 14 Freescale Semiconductor...
Страница 34: ...PCB and MC13192EVB Interfaces MC13192EVB Reference Manual Rev 1 2 4 2 Freescale Semiconductor...