AN 822: Intel® FPGA Configuration Device Migration Guideline

ID 683340
Date 4/29/2020
Document Table of Contents IBIS Simulation Example

In this board design guidelines, the following IBIS simulation was performed to provide recommendation on the topology to estimate the minimum and maximum delays that can be achieved on the DCLK and DATA signals.

The FPGA26 and EPCQ-A IBIS models are used in the following IBIS simulation example by adding extra RC network or buffer on the DCLK signal. The simulation result is used to ensure the delay added on the DCLK is sufficient to meet the actual FPGA tDH and tDSU specifications and ensure the signal quality is good.

IBIS Simulation Setup for Arria® V, Cyclone® V, and Stratix® V Devices

  • Cyclone® V LVTTL-3.0V I/O model is used in the IBIS simulation example shown below
    • DCLK: lvttl30_ctnio_d12s1
    • DATA: lvttl30_ctnio_d8s1
  • Arria® V LVTTL-3.0V I/O model
    • DCLK: lvttl30_ctio_d12s1
    • DATA: lvttl30_ctio_d8s1
  • Stratix® V LVTTL-3.3V I/O model
    • DCLK: lvttl_ctnio_d12s1
    • DATA: lvttl_ctnio_d8s1
  • Table 22.  RLC Value Used for the DCLK and DATA PinsThe RLC value could be varied depending on the package size.
    Pin Name R (mΩ) L (nH) C (pF)
    DCLK 252.71 2.26 1.07
    DATA 633.45 5.61 1.74
  • Intel® EPCQ64ASI16N model is used
  • VCC at 3.3V ±5% is used for both the FPGA and flash devices
  • One inch trace with 50Ω trace impedance on the typical FR4 board is used
  • Simulation is done on both the Slow and Fast IC corners

In addition, Hyperlynx IBIS simulation is used to predict the effects of a given link. The delay of a given link can be estimated accurately using the technique of comparing the simulated delay between the default setup (Configuration 1) and the actual system setup (Configuration 2) as shown in the figure below. The actual use of this methodology to measure the AS configuration timing are performed in the following section.

Figure 8. Simulated Delay Comparison
Note: When measuring the delay of a signal at 50% of the voltage level as shown in the figure below, the IBIS simulation was performed by measuring the voltage at 50% of the voltage level. You can measure at the voltage input high (VIH ) or voltage input low (VIL ) level.
Figure 9. Voltage Level Delay Measurement
26 The Cyclone® V FPGA is used in the following IBIS simulation example.