Stratix® V Device Handbook: Volume 1: Device Interfaces and Integration

ID 683665
Date 10/18/2023
Public
Document Table of Contents

6.2.2.2. Altera_PLL Parameter Values for External PLL Mode

The following examples show the clocking requirements to generate output clocks for ALTLVDS_TX and ALTLVDS_RX using the Altera_PLL IP core. The examples set the phase shift with the assumption that the clock and data are edge aligned at the pins of the device.

Note: For other clock and data phase relationships, Altera recommends that you first instantiate your ALTLVDS_RX and ALTLVDS_TX interface without using the external PLL mode option. Compile the IP cores in the Intel® Quartus® Prime software and take note of the frequency, phase shift, and duty cycle settings for each clock output. Enter these settings in the Altera_PLL IP core parameter editor and then connect the appropriate output to the ALTLVDS_RX and ALTLVDS_TX IP cores.
Table 56.  Example: Generating Output Clocks Using an Altera_PLL IP Core (No DPA and Soft-CDR Mode) This table lists the parameter values that you can set in the Altera_PLL parameter editor to generate three output clocks using an Altera_PLL IP core if you are not using DPA and soft-CDR mode.
Parameter

outclk0

(Connects to the tx_inclock port of ALTLVDS_TX and the rx_inclock port of ALTLVDS_RX)

outclk1

(Connects to the tx_enable port of ALTLVDS_TX and the rx_enable port of ALTLVDS_RX)

outclk2

(Used as the core clock for the parallel data registers for both transmitter and receiver, and connects to the rx_synclock port of ALTLVDS_RX)

Frequency

data rate

data rate/serialization factor

data rate/serialization factor

Phase shift

–180°

[(deserialization factor – 2)/deserialization factor] x 360°

–180/serialization factor

(outclk0 phase shift divided by the serialization factor)

Duty cycle

50%

100/serialization factor

50%

The calculations for phase shift, using the RSKM equation, assume that the input clock and serial data are edge aligned. Introducing a phase shift of –180° to sampling clock (c0) ensures that the input data is center-aligned with respect to the outclk0, as shown in the following figure.

Figure 114. Phase Relationship for External PLL Interface Signals


Table 57.  Example: Generating Output Clocks Using an Altera_PLL IP Core (With DPA and Soft-CDR Mode)This table lists the parameter values that you can set in the Altera_PLL parameter editor to generate four output clocks using an Altera_PLL IP core if you are using DPA and soft-CDR mode. The locked output port of Altera_PLL must be inverted and connected to the pll_areset port of the ALTLVDS_RX IP core if you are using DPA and soft-CDR mode.
Parameter

outclk0

(Connects to the tx_inclock port of ALTLVDS_TX and the rx_inclock port of ALTLVDS_RX)

outclk1

(Connects to the tx_enable port of ALTLVDS_TX and the rx_enable port of ALTLVDS_RX)

outclk2

(Used as the core clock for the parallel data registers for both transmitter and receiver, and connects to the rx_synclock port of ALTLVDS_RX)

outclk3

(Connects to the rx_dpaclock port of ALTLVDS_RX)

Frequency

data rate

data rate/serialization factor

data rate/serialization factor

data rate

Phase shift

–180°

[(deserialization factor - 2)/deserialization factor] x 360°

–180/serialization factor

(outclk0 phase shift divided by the serialization factor)

–180°

Duty cycle

50%

100/serialization factor

50%

50%