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

The multi-channel waveform monitoring technique enhances the 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-μm CMOS technology, demonstrated on-chip waveform acquisition at 40-ps and 200-μV 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 μm × 600 μm was occupied by a single waveform acquisition kernel that was shared with eight front-end modules of 60 μm × 200 μm each. The developed on-chip multi-channel waveform monitoring technique is waveform accurate, area efficient, and low cost, which are all requisite factors for a diagnosing methodology toward mixed analog and digital signal integrity in the system-on-chip era.