ML145170
LANSDALE Semiconductor, Inc.
PHASE–LOCKED LOOP—LOW PASS FILTER DESIGN
φ
(A)
ω
ω
ζ
φ
φ
(B)
ω
ζ
ω
φ
(C)
φ
ω
φ
φ
ω
ζ
NOTES:
1. For (C), R is frequently split into two series resistors; each resistor is equal to R divided by 2. A capacitor C is then placed from
1
1
C
the midpoint to ground to further filter the error pulses. The value of C should be such that the corner frequency of this network
C
does not significantly affect ω .
n
2. The φR and φV outputs swing rail–to–rail. Therefore, the user should be careful not to exceed the common mode input range of
the op amp.
3. For the latest information on MC33077 or equivalent, contact ON Semiconductor.
DEFINITIONS:
N = Total Division Ratio in Feedback Loop
K (Phase Detector Gain) = V / 4π volts per radian for PD
φ
DD
out
K (Phase Detector Gain) = V /2π volts per radian for φ and φ
φ
DD
V
R
2π∆f
∆V
VCO
K
VCO
(VCO Gain) =
VCO
For a nominal design starting point, the user might consider a damping factor ζ ≈ 0.7 anda natural loop frequency ω ≈ (2πf /50) where
n
R
f
is the frequency at the phase detector input. Larger ω values result in faster loop lock times and, for similar sideband filtering,higher
R
n
f –related VCO sidebands.
R
RECOMMENDED READING:
Gardner, Floyd M., Phaselock Techniques (second edition). New York, Wiley–Interscience, 1979.
Manassewitsch, Vadim, Frequency Synthesizers: Theory and Design (second edition). New York, Wiley–Interscience, 1980.
Blanchard, Alain, Phase–Locked Loops: Application to Coherent Receiver Design, New York, Wiley–Interscience, 1976.
Egan, William F.,Frequency Synthesis by Phase Lock, New York, Wiley–Interscience, 1981
Rohde, Ulrich, L., Digital PLL Frequency Synthesizers Theory and Design, Englewood Cliffs, NJ, Prentice–Hall 1983.
Berlin, Howard M., Design of Phase–Locked Loop Circuits with Experiments, Indianapolis, Howard W. Sams and Co. 1978.
Kinley, Harold., The PLL Synthesizer Cookbook, Blue Ridge Summit, PA, Tab Books, 1980.
Seidman, Arthur H., Integrated Circuits Applications Handbook, Chapter 17, pp. 538-586. New York, John Wiley & Sons.
Fadrhons, Jan, “Design and Analyze PLLs on a Programmable Calculator,”EDN. March 5, 1980.
AN535, Phase–Locked Loop Design Fundamentals, Motorola Semiconductor Products, Inc.
AR254, Phase–Locked Loop Design Articles, Motorola Semiconductor Products, Inc., Reprinted with permission from Electronic Design,
1987.
AN1207, The MC145170 in Basic HF and VHF Oscillators, Motorola Semiconductor Products, Inc., 1992.
AN1671, MC145170 PSpice Modeling Kit, Motorola Semiconductor Products, Inc., 1998.
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