On-chip multi-channel waveform monitoring for diagnostics of mixed-signal VLSI circuits

Multi-channel waveform monitoring technique enhances built-in test and diagnostic capability of mixed-signal VLSI circuits. An 8-channel prototype system incorporates adaptive sample time generation with a 10-bit variable step delay generator and algorithmic digitization with a 10-bit incremental reference voltage generator The prototype in a 0.18-mu m CMOS technology demonstrated on-chip waveform acquisition at 40-ps and 200-mu V resolutions. The waveforms were as accurate as those by an off-chip measurement technique, while more than 95% reduction of the waste time in waveform monitoring was achieved. The area of 700 mu m x 600 mu m was occupied by a single waveform acquisition kernel that was shared with 8 front-end modules of 600 mu m x 200 mu m each. The developed on-chip multi-channel waveform monitoring technique is waveform accurate, area efficient, and low cost, which are all requisite factors for diagnosing methodology toward mixed analog and digital signal integrity in a systems-on-a-chip era.