A stand-alone integrated test core for time and frequency domain measurements

An area efficient and robust integrated test core for mixed-signal circuits is described. The core consists of a completely digital implementation, except for a simple reconstruction filter and a comparator. It is capable of both generating arbitrary band-limited waveforms (for excitation purposes) and coherently digitizing arbitrary periodic analog waveforms (for DSP-based test and measurement). A prototype IC was fabricated in a 3.3 V 0.35 μm CMOS process. It was demonstrated to perform various curve tracing, timing, and spectrum analysis tasks at a sampling frequency of 20 MHz (which was only limited by our experimental setup) while taking up an area equivalent to only about five thousand standard-cell 2-input NAND gates