Primitive: Base Phase-Locked Loop (PLL)
- PRIMITIVE_GROUP: CLOCK
- PRIMITIVE_SUBGROUP: PLL
- Families: UltraScale, UltraScale+
Introduction
The PLLE3 is used for high-speed I/O clocking using Bitslice components as well as general clocking requirements. In general, the PLLE3 has less jitter and reduced power characteristics compared to the MMCME3 which makes it preferable for clocking behaviors that do not require features only available to the MMCME3.
Port Descriptions
Port | Direction | Width | Function |
---|---|---|---|
CLKIN | Input | 1 | Clock input. |
LOCKED | Output | 1 | An output from the PLL that indicates when the PLL has achieved phase alignment within a predefined window and frequency matching within a predefined PPM range. The PLL automatically locks after power on, no extra reset is required. LOCKED will be deasserted if the input clock stops or the phase alignment is violated (for example, input clock phase shift). The PLL must be reset after LOCKED is deasserted. |
Clock Outputs: User configurable clock outputs that can be divided versions of the VCO phase outputs (user controllable) from 1 (bypassed) to 256. The output clocks are phase aligned to each other (unless phase shifted) and aligned to the input clock with a proper feedback configuration. | |||
CLKOUTPHY | Output | 1 | General clock output connected to I/O Bitslice components. |
CLKOUT0 | Output | 1 | General clock output CLKOUT0. Generally connected to a global buffer. |
CLKOUT0B | Output | 1 | Inverted CLKOUT0. Generally connected to a global buffer. |
CLKOUT1 | Output | 1 | General clock output CLKOUT1. Generally connected to a global buffer. |
CLKOUT1B | Output | 1 | Inverted CLKOUT1. Generally connected to a global buffer. |
Control Ports: PLL control ports. | |||
CLKOUTPHYEN | Input | 1 | Enable signal for CLKOUTPHY. |
PWRDWN | Input | 1 | Powers down instantiated but unused PLLs. |
RST | Input | 1 | The RST signal is an asynchronous reset for the PLL. The PLL will synchronously re-enable itself when this signal is released and go through a new phase alignment and lock cycle. A reset is required when the input clock conditions change (for example, frequency). |
Feedback Clocks: Required ports to form the feedback path for the PLL phase alignment capabilities. | |||
CLKFBIN | Input | 1 | Feedback clock pin to the PLL. |
CLKFBOUT | Output | 1 | Dedicated PLL Feedback clock output. |
Design Entry Method
Instantiation | Yes |
Inference | No |
IP and IP Integrator Catalog | Recommended |
Available Attributes
Attribute | Type | Allowed Values | Default | Description |
---|---|---|---|---|
CLKFBOUT_MULT | DECIMAL | 1 to 19 | 5 | Specifies the amount to multiply all CLKOUT clock outputs if a different frequency is desired. This number, in combination with the associated CLKOUT#_DIVIDE value and DIVCLK_DIVIDE value, will determine the output frequency. |
CLKFBOUT_PHASE | 3 significant digit FLOAT | -360.000 to 360.000 | 0.000 | Specifies the phase offset in degrees of the clock feedback output. Shifting the feedback clock results in a negative phase shift of all output clocks to the PLL. |
CLKIN_PERIOD | FLOAT(nS) | 0.000 to 14.286 | 0.000 | Specifies the input period in ns to the PLL CLKIN input. Resolution is down to the ps (3 decimal places). For example, a value of 33.333 would indicate a 30 MHz input clock. This information is mandatory and must be supplied. |
CLKOUTPHY_MODE | STRING | "VCO_2X", "VCO", "VCO_HALF" | "VCO_2X" | Specifies the frequency of the CLKOUTPHY clock output. |
DIVCLK_DIVIDE | DECIMAL | 1 to 15 | 1 | Specifies the division ratio for all output clocks with respect to the input clock. Effectively divides the CLKIN going into the PFD. |
REF_JITTER | 3 significant digit FLOAT | 0.000 to 0.999 | 0.010 | Allows specification of the expected jitter on CLKIN to better optimize PLL performance. A bandwidth setting of OPTIMIZED will attempt to choose the best parameter for input clocking when unknown. If known, then the value provided should be specified in terms of the UI percentage (the maximum peak to peak value) of the expected jitter on the input clock. |
STARTUP_WAIT | STRING | "FALSE", "TRUE" | "FALSE" | Delays configuration DONE signal from asserting until PLL is locked. |
CLKOUT0 Attributes: Sets the Divide, Phase, and Duty Cycle for the CLKOUT0 output. | ||||
CLKOUT0_DIVIDE | DECIMAL | 1 to 128 | 1 | Specifies the amount to divide the CLKOUT0 output. This number in combination with the CLKFBOUT_MULT and DIVCLK_DIVIDE values will determine the output frequency. |
CLKOUT0_DUTY_CYCLE | 3 significant digit FLOAT | 0.001 to 0.999 | 0.500 | Specifies the Duty Cycle of CLKOUT0 clock output in percentage (i.e., 0.500 will generate a 50% duty cycle). |
CLKOUT0_PHASE | 3 significant digit FLOAT | -360.000 to 360.000 | 0.000 | Specifies the phase offset in degrees of the CLKOUT0 output. |
CLKOUT1 Attributes: Sets the Divide, Phase, and Duty Cycle for the CLKOUT1 output. | ||||
CLKOUT1_DIVIDE | DECIMAL | 1 to 128 | 1 | Specifies the amount to divide the CLKOUT1 output. This number in combination with the CLKFBOUT_MULT and DIVCLK_DIVIDE values will determine the output frequency. |
CLKOUT1_DUTY_CYCLE | 3 significant digit FLOAT | 0.001 to 0.999 | 0.500 | Specifies the Duty Cycle of CLKOUT1 clock output in percentage (i.e., 0.500 will generate a 50% duty cycle). |
CLKOUT1_PHASE | 3 significant digit FLOAT | -360.000 to 360.000 | 0.000 | Specifies the phase offset in degrees of the CLKOUT1 output. |
Programmable Inversion Attributes: Specifies whether or not to use the optional inversions on specific pins of this component to change the active polarity of the pin function. When set to 1 on a clock input pin (CLKIN or CLKFBIN), the phase is effectively shifted 180 degrees. When set to 1 on other pins, it changes the function to behave active-Low rather than active-High. If an external inverter is specified on one of these associated pins, the Vivado Design Suite will automatically set this attribute during the opt_design stage so that additional logic is not necessary for changing the input polarity. | ||||
IS_CLKFBIN_INVERTED | BINARY | 1'b0 to 1'b1 | 1'b0 | Specifies whether or not to use the optional inversion on the CLKFBIN pin of this component. |
IS_CLKIN_INVERTED | BINARY | 1'b0 to 1'b1 | 1'b0 | Specifies whether or not to use the optional inversion on the CLKIN pin of this component. |
IS_PWRDWN_INVERTED | BINARY | 1'b0 to 1'b1 | 1'b0 | Specifies whether or not to use the optional inversion on the PWRDWN pin of this component. |
IS_RST_INVERTED | BINARY | 1'b0 to 1'b1 | 1'b0 | Specifies whether or not to use the optional inversion on the RST pin of this component. |
VHDL Instantiation Template
Unless they already exist, copy the following
two statements and paste them before the entity declaration.
Library UNISIM;
use UNISIM.vcomponents.all;
-- PLLE3_BASE: Base Phase-Locked Loop (PLL)
-- UltraScale
-- Xilinx HDL Language Template, version 2022.1
PLLE3_BASE_inst : PLLE3_BASE
generic map (
CLKFBOUT_MULT => 5, -- Multiply value for all CLKOUT, (1-19)
CLKFBOUT_PHASE => 0.0, -- Phase offset in degrees of CLKFB, (-360.000-360.000)
CLKIN_PERIOD => 0.0, -- Input clock period in ns to ps resolution (i.e., 33.333 is 30 MHz).
-- CLKOUT0 Attributes: Divide, Phase and Duty Cycle for the CLKOUT0 output
CLKOUT0_DIVIDE => 1, -- Divide amount for CLKOUT0 (1-128)
CLKOUT0_DUTY_CYCLE => 0.5, -- Duty cycle for CLKOUT0 (0.001-0.999)
CLKOUT0_PHASE => 0.0, -- Phase offset for CLKOUT0 (-360.000-360.000)
-- CLKOUT1 Attributes: Divide, Phase and Duty Cycle for the CLKOUT1 output
CLKOUT1_DIVIDE => 1, -- Divide amount for CLKOUT1 (1-128)
CLKOUT1_DUTY_CYCLE => 0.5, -- Duty cycle for CLKOUT1 (0.001-0.999)
CLKOUT1_PHASE => 0.0, -- Phase offset for CLKOUT1 (-360.000-360.000)
CLKOUTPHY_MODE => "VCO_2X", -- Frequency of the CLKOUTPHY (VCO, VCO_2X, VCO_HALF)
DIVCLK_DIVIDE => 1, -- Master division value, (1-15)
-- Programmable Inversion Attributes: Specifies built-in programmable inversion on specific pins
IS_CLKFBIN_INVERTED => '0', -- Optional inversion for CLKFBIN
IS_CLKIN_INVERTED => '0', -- Optional inversion for CLKIN
IS_PWRDWN_INVERTED => '0', -- Optional inversion for PWRDWN
IS_RST_INVERTED => '0', -- Optional inversion for RST
REF_JITTER => 0.0, -- Reference input jitter in UI (0.000-0.999)
STARTUP_WAIT => "FALSE" -- Delays DONE until PLL is locked (FALSE, TRUE)
)
port map (
-- Clock Outputs outputs: User configurable clock outputs
CLKOUT0 => CLKOUT0, -- 1-bit output: General Clock output
CLKOUT0B => CLKOUT0B, -- 1-bit output: Inverted CLKOUT0
CLKOUT1 => CLKOUT1, -- 1-bit output: General Clock output
CLKOUT1B => CLKOUT1B, -- 1-bit output: Inverted CLKOUT1
CLKOUTPHY => CLKOUTPHY, -- 1-bit output: Bitslice clock
-- Feedback Clocks outputs: Clock feedback ports
CLKFBOUT => CLKFBOUT, -- 1-bit output: Feedback clock
LOCKED => LOCKED, -- 1-bit output: LOCK
CLKIN => CLKIN, -- 1-bit input: Input clock
-- Control Ports inputs: PLL control ports
CLKOUTPHYEN => CLKOUTPHYEN, -- 1-bit input: CLKOUTPHY enable
PWRDWN => PWRDWN, -- 1-bit input: Power-down
RST => RST, -- 1-bit input: Reset
-- Feedback Clocks inputs: Clock feedback ports
CLKFBIN => CLKFBIN -- 1-bit input: Feedback clock
);
-- End of PLLE3_BASE_inst instantiation
Verilog Instantiation Template
// PLLE3_BASE: Base Phase-Locked Loop (PLL)
// UltraScale
// Xilinx HDL Language Template, version 2022.1
PLLE3_BASE #(
.CLKFBOUT_MULT(5), // Multiply value for all CLKOUT, (1-19)
.CLKFBOUT_PHASE(0.0), // Phase offset in degrees of CLKFB, (-360.000-360.000)
.CLKIN_PERIOD(0.0), // Input clock period in ns to ps resolution (i.e., 33.333 is 30 MHz).
// CLKOUT0 Attributes: Divide, Phase and Duty Cycle for the CLKOUT0 output
.CLKOUT0_DIVIDE(1), // Divide amount for CLKOUT0 (1-128)
.CLKOUT0_DUTY_CYCLE(0.5), // Duty cycle for CLKOUT0 (0.001-0.999)
.CLKOUT0_PHASE(0.0), // Phase offset for CLKOUT0 (-360.000-360.000)
// CLKOUT1 Attributes: Divide, Phase and Duty Cycle for the CLKOUT1 output
.CLKOUT1_DIVIDE(1), // Divide amount for CLKOUT1 (1-128)
.CLKOUT1_DUTY_CYCLE(0.5), // Duty cycle for CLKOUT1 (0.001-0.999)
.CLKOUT1_PHASE(0.0), // Phase offset for CLKOUT1 (-360.000-360.000)
.CLKOUTPHY_MODE("VCO_2X"), // Frequency of the CLKOUTPHY (VCO, VCO_2X, VCO_HALF)
.DIVCLK_DIVIDE(1), // Master division value, (1-15)
// Programmable Inversion Attributes: Specifies built-in programmable inversion on specific pins
.IS_CLKFBIN_INVERTED(1'b0), // Optional inversion for CLKFBIN
.IS_CLKIN_INVERTED(1'b0), // Optional inversion for CLKIN
.IS_PWRDWN_INVERTED(1'b0), // Optional inversion for PWRDWN
.IS_RST_INVERTED(1'b0), // Optional inversion for RST
.REF_JITTER(0.0), // Reference input jitter in UI (0.000-0.999)
.STARTUP_WAIT("FALSE") // Delays DONE until PLL is locked (FALSE, TRUE)
)
PLLE3_BASE_inst (
// Clock Outputs outputs: User configurable clock outputs
.CLKOUT0(CLKOUT0), // 1-bit output: General Clock output
.CLKOUT0B(CLKOUT0B), // 1-bit output: Inverted CLKOUT0
.CLKOUT1(CLKOUT1), // 1-bit output: General Clock output
.CLKOUT1B(CLKOUT1B), // 1-bit output: Inverted CLKOUT1
.CLKOUTPHY(CLKOUTPHY), // 1-bit output: Bitslice clock
// Feedback Clocks outputs: Clock feedback ports
.CLKFBOUT(CLKFBOUT), // 1-bit output: Feedback clock
.LOCKED(LOCKED), // 1-bit output: LOCK
.CLKIN(CLKIN), // 1-bit input: Input clock
// Control Ports inputs: PLL control ports
.CLKOUTPHYEN(CLKOUTPHYEN), // 1-bit input: CLKOUTPHY enable
.PWRDWN(PWRDWN), // 1-bit input: Power-down
.RST(RST), // 1-bit input: Reset
// Feedback Clocks inputs: Clock feedback ports
.CLKFBIN(CLKFBIN) // 1-bit input: Feedback clock
);
// End of PLLE3_BASE_inst instantiation
Related Information
- See the UltraScale Architecture Clocking Resources User Guide (UG572).