This section of the MIG Design Assistant focuses onCalibrated Input Termination IBIS Simulation for Spartan-6 MCB designs.
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MIG can provide calibrated on-die input termination for DDR2 and DDR3 memory interfaces. When this option is selected, the mcb_soft_calibration module calibrates the input termination for the bidirectional memory interface signals dq, ldqs_p/n, udqs_p/n to an external 100 Ohm pull-up resistor on the RZQ pin. This results in an input termination value that is close to the UNTUNED_SPLIT_50 uncalibrated input termination.
To simulate the MCB interface using Calibrated Input Termination, you mustseparate write and read interfaces in the IBIS simulations and simulate them independently.
To simulate the input, use the SSTL15_IN50M_* model for DDR3 interfaces and the SSTL18_IN50M_* model for DDR2 interfaces.
To simulate the output, use only the driver model and exclude the input buffer mode.
Example: for a standard DDR3 interface on a Spartan-6 MCB with calibrated input termination selected and Vccaux = 2.5 Volts, you use the following models for the DQ/DQS interface: