Altera Phase-Locked Loop User Manual
Page 3
Parameter
Legal Value
Description
Operation Mode
direct,
external
feedback,
normal,
source
synchronous,
zero delay
buffer, or lvds
Specifies the operation of the PLL. The default operation is
direct mode.
• If you select the direct mode, the PLL minimizes the
length of the feedback path to produce the smallest
possible jitter at the PLL output.The internal-clock and
external-clock outputs of the PLL are phase-shifted with
respect to the PLL clock input. In this mode, the PLL
does not compensate for any clock networks.
• If you select the normal mode, the PLL compensates for
the delay of the internal clock network used by the clock
output. If the PLL is also used to drive an external clock
output pin, a corresponding phase shift of the signal on
the output pin occurs.
• If you select the source synchronous mode, the clock
delay from pin to I/O input register matches the data
delay from pin to I/O input register.
• If you select the external feedback mode, you must
connect the
fbclk
input port to an input pin. A board-
level connection must connect both the input pin and
external clock output port,
fboutclk
. The
fbclk
port is
aligned with the input clock.
• If you select the zero delay buffer mode, the PLL must
feed an external clock output pin and compensate for the
delay introduced by that pin. The signal observed on the
pin is synchronized to the input clock. The PLL clock
output connects to the
altbidir
port and drives
zdbfbclk
as an output port. If the PLL also drives the
internal clock network, a corresponding phase shift of
that network occurs.
• If you select the lvds mode, the same data and clock
timing relationship of the pins at the internal SERDES
capture register is maintained. The mode compensates
for the delays in LVDS clock network, and between the
data pin and clock input pin to the SERDES capture
register paths.
Enable locked output port
Turn on or
Turn off
Turn on to enable the
locked
port.
Enable physical output
clock parameters
Turn on or
Turn off
Turn on to enter physical PLL counter parameters instead of
specifying a desired output clock frequency.
Number of Clocks
Stratix V and
Arria V: 1–18,
Cyclone V: 1–
9
Specifies the number of output clocks required for each
device in the PLL design. The requested settings for output
frequency, phase shift, and duty cycle are shown based on
the number of clocks selected.
UG-01087
2015.05.04
Altera PLL IP Core Parameters - General Tab
3
Altera Phase-Locked Loop (Altera PLL) IP Core User Guide
Altera Corporation