****************************************************************************** ********************* IBIS GOLDEN PARSER BUG REPORT FORM ********************* ****************************************************************************** INSTRUCTIONS To report a bug in the IBIS golden parser. Please fill out the top part of the following form and send the complete form to ibis-bug@eda.org. A list of reported bugs will be maintained on eda.org. ****************************************************************************** PARSER VERSION NUMBER: 5.0.6 PLATFORM (SPARC, HP700, PC, etc.): ALL OS AND VERSION: WIN7, Linux RHL REPORTED BY: Lance Wang, I/O Methodology DATE: July 21, 2011 DESCRIPTION OF BUG: ibischk5 gives errors when [composite Current] table time points are not identical with VT curve time points as shown below. ERROR - Model Model1: Rising Waveform [1] and its Composite Current don't have identical time points ERROR - Model Model1: Falling Waveform [1] and its Composite Current don't have identical time points These errors are based on the spec statement: | The I-T table data must be time-correlated with the V-T data | above it. That is, the currents documented in the I-T table | correspond to the voltages in the V-T table at the identical | time points and for the given *_fixture load. It is not critical for EDA tools to use these data if given enough points for interpolation. There are few simulators that support this feature now (currently they remove these errors in the parser messages). These error messages should be downgraded to NOTE. Some background: 1. VT and IT curves in the same IBIS Model needs to cover the same time period to insure the accuracy for using IT curves in the simulations. It should not be the identical time step points. (a BIRD for clarification will be issued later.) 2. Recently, IBIS 3.2 is still the mainstream for IBIS model distributions due to simulator support. Point reduction is needed for IBIS 3.2 IV and VT curves. For ease of version downgrade, IBIS 5.0 file would best use 100 VT points but 1000 points for IT curves. 3. This is a blocking bug for chip vendors to distribute IBIS 5.0 models due to double support needed for both 3.2 and 5.0 models. ------ Added note from Bob Ross: The IBIS Version 5.0 Specification requires that V-T and I-T times be exactly aligned. This appears to be unnecessary. However, this BUG129 report demotes the time alignment check from an Error to a Caution message for ibischk5.0.x to support existing tools and models. If BIRD141 is accepted, then ibischk5.1.x would remove the check entirely. INSERT IBIS FILE DEMONSTRATING THE BUG: |************************************************************************** | [IBIS Ver] 5.0 [File name] bug129.ibs [Date] July 25, 2011 [File Rev] 0.0 [Source] From silicon level SPICE model [Notes] This is a dummy IBIS file for buffer model holding [Disclaimer] provided as is |*************************************************************************** | COMPONENT: BUFFERHODLER |*************************************************************************** | [Component] BUG129_TEST [Manufacturer] TestCase [Package] | typ min max R_pkg 0 0 0 L_pkg 0 0 0 C_pkg 0 0 0 | [Pin] signal_name model_name R_pin L_pin C_pin 1 Signal Model1 0 0 0 | |*************************************************************************** | [Model] Model1 Model_type I/O Polarity Non-Inverting Enable Active-Low Vinl = 0.8 Vinh = 2 Vmeas = 1.65 Vref = 1.65 Cref = 15pF Rref = 50 | | typ min max | C_comp 2.588e-012 2.373e-012 2.656e-012 |C_comp (ON state) 3.508e-012 3.029e-012 3.676e-012 |C_comp (OFF state) 1.668e-012 1.717e-012 1.636e-012 [Voltage Range] 3.3 3.1 3.5 [Temperature Range] 25 100 0 [Pullup Reference] 3.3 3.1 3.5 [Pulldown Reference] 0 0 0 [Power Clamp Reference] 3.3 3.1 3.5 [GND Clamp Reference] 0 0 0 | |*************************************************************************** | [Pulldown] | | | Voltage I(typ) I(min) I(max) | 0 -3.38738e-008 -6.87524e-009 -6.36258e-008 1.96 0.0253159 0.0180257 0.0311249 6.6 0.0269179 0.0192363 0.0329351 | [Pullup] | | Voltage I(typ) I(min) I(max) | 0 -1.00312e-008 -1.00249e-008 -7.29422e-009 2.0405 -0.024349 -0.0166121 -0.0303963 6.6 -0.0305378 -0.0210585 -0.0376153 | |*********************************************************************** | [Ramp] R_load = 50 | | typ min max | dV/dt_r 0.732026/1.62512e-009 0.504507/2.22397e-009 0.90718/1.39336e-009 dV/dt_f 0.760214/1.73429e-009 0.542235/2.45827e-009 0.933557/1.45171e-009 | |************************************************************************ | [Falling Waveform] V_fixture = 3.3V V_fixture_min = 3.1V V_fixture_max = 3.5V R_fixture = 50Ohm C_fixture = 0F | | Time V(typ) V(min) V(max) | 0 3.3 3.1 3.5 | Extra V-T Point. Comment out to remove error. 1.4e-9 2.0 2.0 1.9 | Extra | V-T Point 1.5e-009 2.03298 2.19628 1.94407 | [Composite Current] | Time I(typ) I(min) I(max) | 0 8.88178e-011 8.92619e-009 8.88178e-011 1.5e-009 4.89505e-005 0.00010379 0.00010379 | [Rising Waveform] V_fixture = 0V V_fixture_min = 0V V_fixture_max = 0V R_fixture = 50Ohm C_fixture = 0F | | Time V(typ) V(min) V(max) | 0 0 0 0 1.5e-009 1.22004 0.840845 1.51197 | [Composite Current] | Time I(typ) I(min) I(max) | 0 8.88178e-011 7.77156e-009 4.44089e-011 | Extra I-T Point. comment out to remove error. 1.4e-009 0.0 0.0 0.0 1.5e-009 0.0244501 0.0303743 0.0303743 | [End] ****************************************************************************** ******************** BELOW FOR ADMINISTRATION AND TRACKING ******************* ****************************************************************************** BUG NUMBER: 129 SEVERITY: [FATAL, SEVERE, MODERATE, ANNOYING, ENHANCEMENT] MODERATE PRIORITY: [HIGH, MEDIUM, LOW] MEDIUM STATUS: [OPEN, CLOSED, WILL NOT FIX, NOT A BUG] CLOSED FIXED VERSION: 5.0.7 FIXED DATE: October 7,2011 NOTES ON BUG FIX: Classified at the August 5, 2011 meeting. To be fixed in a future release. BIRD141, approved September 16, 2011 removed the time point alighment requirement. The mismatch is reduced to a Caution message. When BIRD141 is added to the IBIS Specification, the test will be removed. ****************************************************************************** ******************************************************************************