Intel® Agilex™ Clocking and PLL User Guide

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ID 683761
Date 3/26/2022
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5.4.1. IOPLL IP Core Parameters - PLL Tab

Table 8.   IOPLL IP Core Parameters - PLL Tab for Intel® Agilex™ Devices
Parameter Value Description
Device Family Intel® Agilex™ Specifies the device family.
Component Specifies the targeted device.
Speed Grade Specifies the speed grade for targeted device.
IOPLL Type Fabric-Feeding, I/O Bank Select the type of the I/O PLL. The fabric-feeding I/O PLL locations have fewer outclks than the I/O bank I/O PLLs, and cannot be used as External I/O PLL in the LVDS SERDES Intel® FPGA IP core.
Reference Clock Frequency Specifies the input frequency for the input clock, refclk, in MHz. The default value is 100.0 MHz. The minimum and maximum value is dependent on the selected device.
Refclk source is global clock On or Off Specifies whether the reference clock source is a global clock. Intel recommends using a dedicated reference clock pin instead of a global clock to minimize jitter. If a global reference clock source is required, this clock must still be promoted using the Assignment Editor.
Enable Locked Output Port On or Off Turn on to enable the locked port.
Enable physical output clock parameters On or Off Turn on to enter physical PLL counter parameters instead of specifying a desired output clock frequency.
Compensation Mode direct, external feedback 6, normal, source synchronous, zero delay buffer 6, or lvds 6 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 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 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 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.
Compensated Outclk 7 06 Allows you to select which output clock (outclk) to be compensated. The feedback mode compensates for the clock network delay of the outclk selected. This feedback mode ensures correct phase relationship between I/O PLL input and output clocks only for the selected outclk.
Use Nondedicated Feedback Path 7 On or Off Turn on to conserve clock resources and improve timing analysis. However, this feature creates frequency limitations and disables phase shift.
Number of Clocks 13 (fabric-feeding), 17 (I/O bank) 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.
Multiply Factor (M-Counter) 8 4160 Specifies the multiply factor of M-counter.
Divide Factor (N-Counter) 8 1110 Specifies the divide factor of N-counter.
Specify VCO Frequency On or Off Allows you to restrict the VCO frequency to the specified value. This is useful when creating a PLL for LVDS external mode, or if a specific dynamic phase shift step size is desired.
Desired VCO Frequency 9 Specifies the VCO frequency for the PLL in MHz. The default value is 600.0 MHz.
Actual VCO Frequency
  • When Enable physical output clock parameters is turned on—displays the VCO frequency based on the values for Reference Clock Frequency, Multiply Factor (M-Counter), and Divide Factor (N-Counter).
  • When Enable physical output clock parameters is turned off and Specify VCO frequency is turned on—allows you to specify the requested value for the VCO frequency. The default value is 600.0 MHz.
Give clock global name On or Off Allows you to rename the output clock name.
Clock Name The user clock name for Synopsis Design Constraints (SDC).
Divide Factor (C-Counter) 8 1512 Specifies the divide factor for the output clock (C-counter).
Desired Frequency Specifies the output clock frequency of the corresponding output clock port, outclk[], in MHz. The default value is 100.0 MHz. The minimum and maximum values depend on the device used. The PLL only reads the numerals in the first six decimal places.
Actual Frequency Allows you to select the actual output clock frequency from a list of achievable frequencies. The default value is the closest achievable frequency to the desired frequency.
Phase Shift units ps or degrees Specifies the phase shift unit for the corresponding output clock port, outclk[], in picoseconds (ps) or degrees.
Desired Phase Shift Specifies the requested value for the phase shift. The default value is 0 ps.
Actual Phase Shift Allows you to select the actual phase shift from a list of achievable phase shift values. The default value is the closest achievable phase shift to the desired phase shift.
Desired Duty Cycle 0.0100.0 Specifies the requested value for the duty cycle. The default value is 50.0%.
Actual Duty Cycle Allows you to select the actual duty cycle from a list of achievable duty cycle values. The default value is the closest achievable duty cycle to the desired duty cycle.
6 This option is only available when selecting I/O Bank on the IOPLL Type.
7 This option is only available when either normal or source synchronous mode is selected.
8 This parameter is only available when Enable physical output clock parameters is turned on.
9 This parameter is only available when Specify VCO Frequency is turned on and Enable physical output clock parameters is turned off.

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