AN1833 Freescale Semiconductor / Motorola, AN1833 Datasheet - Page 12

• Manufacturer Part Number: AN1833
• Description: A Low-Power Wireless Remote Control Transmitter and Receiver
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
12
The oscillator tuning range is controlled by C resulting from the voltage
variable CV. The following equation by similarity to equation (2) above
shows this relationship.
The oscillator operating frequency may be estimated by the next
equation, which is derived by substituting equation (2) for C in equation
(1).
where C1 = C2 = 18 pF
For an oscillator center frequency of 394.7 MHz (high side LO is used),
the value of L is calculated to be 11.5 nH.
For a more in-depth study, Randall Rhea discusses several oscillator
circuits in his book on oscillator design [7].
Solving (4) for L, results in:
3.
4. f = (0.159) / [
5. L = (0.159)
Freescale Semiconductor, Inc.
For More Information On This Product,
CS = 4.7 pF
CV = 5 pF (at 2.2 Vdc)
CB = 11 pF
C = (CS + CV)(CB) / (CB + CS + CV)
[ (CS + CV )(CB) / (CB + CS + CV) ] * [L]
[ (CS + CV)(CB) / (CB + CS + CV) ] * f
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2
/
{
{
[ [(C1)(C2)] / [(C1 + C2)] +
[(C1)(C2)] / [(C1 + C2)] +
2
}
}
1/2]
MOTOROLA
AN1833