TDK5111 Просмотр технического описания (PDF) - Infineon Technologies

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производитель

TDK5111

ASK/FSK Transmitter 315 MHz

Infineon Technologies 

TDK 5111

Applications

Example for the FSK-Mode:

FSK modulation is achieved by switching the load capacitance of the crystal as

shown below.

FSKDTA

FSKOUT

Csw

-R

L

COSC

f, CL Cv1

IC

Cv2

The frequency deviation of the crystal oscillator is multiplied with the divider

factor N of the Phase Locked Loop to the output of the power amplifier. In case

of small frequency deviations (up to +/- 1000 ppm), the two desired load

capacitances can be calculated with the formula below.

CL # C0 ∆f (1 + 2(C0 + CL) )

CL± =

N* f1

C1

1 ± ∆f (1 + 2(C0 + CL) )

N* f1

C1

CL: crystal load capacitance for nominal frequency

C0: shunt capacitance of the crystal

f: frequency

ω: ω = 2πf: angular frequency

N: division ratio of the PLL

df: peak frequency deviation

Because of the inductive part of the TDK 5111, these values must be corrected

by formula (1). The value of Cv± can be calculated.

Wireless Components

4-7

Specification, October 2002

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