MC33493DTBR2 Datasheet, PDF (14/22 Pages) Freescale Semiconductor, Inc – PLL Tuned UHF Transmitter for Data Transfer Applications

Complete Application Schematic and PCB for OOK Modulation
Figure 11 shows the output power versus the R_ext resistor value with 50 Ω load and with matching network.
Output power measurement in typical conditions (434MHz - Vcc=3V - 25°C)
8
REXT SPECIFIED RANGE
6
Output power when matched (dBm)
4
-0.35dB/kΩ # -0.35mA/kΩ
2
RFOUT
Level (dBm)
0
-2
-4
Output power on 50Ω load (dBm)
-6
6
9
12
15
18
21
24
Rext (kΩ)
Figure 11. Output Power at 434 MHz Band vs R_ext Value
The 50 Ω matching network used for the 868 MHz band is similar to the 434 MHz, excepting components values: L1 is changed
to 8.2 nH and C3 to 470 pF in Figure 11. The typical gain of this 868 MHz matching network is 4 dB compared to unmatched
configuration.
12 Complete Application Schematic and PCB for OOK
Modulation
Figure 12 shows a complete application schematic using a MC68HC908RK2 microcontroller. OOK modulation is selected,
f_carrier = 433.92 MHz. The C₂ to C₅ capacitors can be removed if switch debounce is done by software.
PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 1.7
14
Freescale Semiconductor