MB15A01 Fujitsu Microelectronics, MB15A01 Datasheet - Page 9

• Manufacturer Part Number: MB15A01
• Description: Bi-cmos 1.1 GHZ PLL Frequency Synthesizer
• Manufacturer: Fujitsu Microelectronics

MB15A01
3. Relation between FC Pin Inputs and Phase Characteristics
The FC pin is the phase switching pin for the phase comparator. Controlling the FC pin inverts the characteristics
of the internal charge pump output (D
parator input monitor pin (fout) is also controlled via the FC pin. The following table lists relation between FC pin
inputs and D
Z: High impedance
When designing a synthesizer, control the FC pin depending on the VCO polarity.
fr > fp
fr < fp
fr = fp
Note: When using an active lowpass filter, pay attention to its polarity
O
• When the VCO polarity is (1)
• When the VCO polarity is (2)
, øR, øP, and fout:
FC: “H” or open
FC: “L”
D
H
L
Z
O
O
) and phase comparator outputs (øR, øP). In addition, the phase com-
FC: “H” (or open)
øR
H
L
L
øP
Z
Z
L
VCO input voltage
fout
fr
D
H
L
Z
O
øR
H
L
L
FC: “L”
(1)
(2)
øP
Z
L
Z
fout
fp
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