EVB7108
868/915MHz Transmitter
Evaluation Board Description
390120710801 6 of 8 EVB Description
Rev. 007 Aug/02
Board Component Values
Part Size
Value
868.3 MHz
Value
915 MHz
Tolerance Description
CF1 0805 5.6 nF 4.7 nF
±10%
loop filter capacitor
CF2 0805 27 pF 27 pF
±10%
loop filter capacitor
CX1
_FSK
0603 56 pF 56 pF
±5% XOSC capacitor for FSK (∆f = ±30 kHz)
CX1
_ASK
0603 18 pF 18 pF
±5%
XOSC capacitor for ASK, trimmed to f
C
CX2 0603 1 nF 1 nF
±5%
XOSC capacitor, only needed for FSK
CX3 0603 1 nF 1 nF
±10%
XOSC capacitor,
only needed for FM
C1 1206 2.2 pF 2.2 pF
±2%
antenna resonance capacitor
C2 0805 1.2 pF 1 pF
±2%
antenna resonance capacitor
C3 0603 330 pF 330 pF
±10%
blocking capacitor
C4 0603 330 pF 330 pF
±10%
blocking capacitor
C5 1206 220 nF 220 nF
±20%
blocking capacitor
L1 0603 150 nH 150 nH
±10%
biasing inductor
L2 0603 150 nH 150 nH
±10%
biasing inductor
RF1 0805
1.6 kΩ 1.6 kΩ±10%
loop filter resistor
RF2 0805
2.0 kΩ 2.0 kΩ±10%
loop filter resistor
RPS 0805
47 kΩ 47 kΩ±10%
power-select resistor
R1 0805
470 kΩ 470 kΩ±10%
optional pull-up resistor, typically not needed
R2 0805
30 kΩ 30 kΩ±10%
varactor bias resistor,
only needed for FM
R3 0805
0 Ω 0 Ω±10%
ASK jumper, only needed for ASK
V1 SOD323 BB535
varactor diode, only needed for FM
XTAL HC49/S
27.1344 MHz
fundamental
wave
28.5938 MHz
fundamental
wave
±30ppm
calibration
±30ppm
temp.
crystal, C
load
= 12 pF to 15 pF, C
0, max
= 7 pF,
R
m, max
= 40 Ω
PCB
loop
antenna
long side
length
18 mm 18 mm
on FR4 PCB material
side length including length of C1 and C2
PCB
loop
antenna
small side
length
9 mm 9 mm on FR4 PCB material
PCB
loop
antenna
Line width 2 mm 2 mm on FR4 PCB material
The listed component values are default values. All values might be changed to fit to any specific application.
As for example FSK deviation can be set by varying CX1 and CX2, output power at FSK/FM transmission
can be changed through RPS or through RPS and R3 at ASK transmission, respectively.
Pads for C1 are for population of a fixed-value capacitor with size 1206 or a to use trimming capacitor either.
