MC145190 Datasheet, PDF (18/24 Pages) Motorola, Inc – 1.1GHz PLL Frequency Synthesizers

frequency (fR) at OUTPUT A as a function of supply voltage.
(REFout is not used because loading impacts the oscillator.)
The frequency should increase very slightly as the dc supply
voltage is increased. An overdriven crystal decreases in fre-
quency or becomes unstable with an increase in supply volt-
age. The operating supply voltage must be reduced or R1
must be increased in value if the overdriven condition exists.
The user should note that the oscillator start–up time is pro-
portional to the value of R1.
Through the process of supplying crystals for use with
CMOS inverters, many crystal manufacturers have devel-
oped expertise in CMOS oscillator design with crystals. Dis-
cussions with such manufacturers can prove very helpful
(see Table 4).
RECOMMENDED READING
Technical Note TN–24, Statek Corp.
Technical Note TN–7, Statek Corp.
E. Hafner, “The Piezoelectric Crystal Unit–Definitions and
Method of Measurement”, Proc. IEEE, Vol. 57, No. 2, Feb.
1969.
D. Kemper, L. Rosine, “Quartz Crystals for Frequency
Control”, Electro–Technology, June 1969.
P. J. Ottowitz, “A Guide to Crystal Selection”, Electronic
Design, May 1966.
D. Babin, “Designing Crystal Oscillators”, Machine
Design, March 7, 1985.
D. Babin, “Guidelines for Crystal Oscillator Design”,
Machine Design, April 25, 1985.
FREQUENCY
SYNTHESIZER
REFin _Rf
R1*
REFout
C1
C2
* May be needed in certain cases. See text.
Figure 19. Pierce Crystal Oscillator Circuit
REFin
Ca
Cin
Cout
Cstray
REFout
Figure 20. Parasitic Capacitances of the Amplifier
and Cstray
RS
LS
CS
1
2
1
2
CO
1
Re Xe
2
NOTE: Values are supplied by crystal manufacturer
(parallel resonant crystal).
Figure 21. Equivalent Crystal Networks
Table 4. Partial List of Crystal Manufacturers
Motorola — Internet Address http://motorola.com (Search for resonators)
United States Crystal Corp.
Crystek Crystal
Statek Corp.
Fox Electronics
NOTE: Motorola cannot recommend one supplier over another and in no way suggests
that this is a complete listing of crystal manufacturers.
MC145190•MC145191
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