# mc13176d ETC-unknow, mc13176d Datasheet - Page 11

#### mc13176d

Manufacturer Part Number

mc13176d

Description

Fm/am Transmitter

Manufacturer

ETC-unknow

Datasheet

1.MC13176D.pdf
(18 pages)

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**mc13176d**R2

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MOT

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Reference Crystal Oscillator (Pins 8 and 9)

number of mechanical modes. The lowest resonant

frequency mode is its fundamental while higher order modes

are called overtones. At each mechanical resonance, a

crystal behaves like a RLC series–tuned circuit having a

large inductor and a high Q. The inductor L s is series

resonance with a dynamic capacitor, C s determined by the

elasticity of the crystal lattice and a series resistance R s ,

which accounts for the power dissipated in heating the

crystal. This series RLC circuit is in parallel with a static

capacitance, C p which is created by the crystal block and by

the metal plates and leads that make contact with it.

resonant mode. It is assumed that other modes of resonance

are so far off frequency that their effects are negligible.

Series resonant frequency, f s is given by;

and parallel resonant frequency, f p is given by;

MOTOROLA RF/IF DEVICE DATA

Selection of Proper Crystal: A crystal can operate in a

Figure 24 is the equivalent circuit for a crystal in a single

f s = 1/2 (L s C s ) 1/2

f p = f s (1 + C s /C p ) 1/2

– 20

– 30

– 40

–10

(dBc)

(dBc)

Figure 22. Modulation Spectrum

Figure 20. Input Data Waveform

MC13175 MC13176

the frequency separation at resonance is given by;

Usually f p is less than 1% higher than f s , and a crystal exhibits

an extremely wide variation of the reactance with frequency

between f p and f s . A crystal oscillator circuit is very stable

with frequency. This high rate of change of impedance with

frequency stabilizes the oscillator, because any significant

change in oscillator frequency will cause a large phase shift

in the feedback loop keeping the oscillator on frequency.

f = f p –f s = f s [1 – (1 + C s /C p ) 1/2 ]

Figure 24. Crystal Equivalent Circuit

Figure 23. Unmodulated Carrier

Figure 21. Frequency Deviation

Cp

R 3

C 3

L 3

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