ADD/CMD/CTRL Line Analysis

Use ADD/CMD/CTRL Line Analysis to analyze interconnect network of command and control group nets of DDR BUS in time domain to obtain the eye diagrams and transient waveforms which are different views of the signal delay and distortion.

The analysis automatically measures setup/hold timing margin and creates a timing margin report.

Creating a network analysis model starts with selecting clock net and CMD/CTRL net from the net listing. The net name is initially assigned to the model name. In case of CMD/CTRL group of DDR BUS, CPU component can only be selected for CMD/CTRL analysis using Active Driver Pin button.

Click Import to select required DDR operation speed then all required timing parameters are automatically filled with pre-defined value in JEDEC specification.

Figure 1.
Click Device Models to view the device models selected for the output and input pins. You can change the device model selection when multiple models are available for the pin.

Figure 2.

The analysis is performed upon selecting Run Analysis menu.

Eye Diagram analysis is running transient circuit simulation on the network model to obtain eye diagrams at the input nodes. An eye diagram or eye pattern is obtained from overlapping multiple waveforms at the receiver node of a net generated by randomly selected high/low states of the input signals for the selected net and adjacent nets. The coupling effects from the adjacent nets are reflected in the waveforms. Prior to running analysis, users can change the analysis control parameters such as the number of random pulses and bit pattern style.

Upon completion of the analysis, the eye diagrams at input nodes are displayed in the waveform viewer. You can also view the required eye-mask and setup/hold margin of each output pin. The eye diagram waveform data can be saved in a file with the use of save menu. Save menu saves the file in Signal_Integrity/Waveform directory under the PCB design job folder. The model name plus .spe is used for the file name. The saved eye diagram waveform data can be read into the waveform viewer alone or together with other eye diagram waveform data.

Figure 3.
The analysis results can be listed in a table form by clicking Show Report tab. They can be also shown in MS Excel.

Figure 4.