Programmable phase/frequency generator for system debug and diagnosis using the IEEE 1149.1 test bus

A method of analog signal generation is presented that is suitable for most digital test methodologies such as that described by the IEEE 1149.1 test standard. The method can be used to produce a wide range of phase and frequency signals for system test debug and diagnosis. The method involves the generation of a 1-bit periodic bit stream through an off-chip software encoding procedure involving a delta-sigma modulator, followed by an on-chip hardware decoding procedure using a phase-locked loop and a circular register or memory. An experimental hardware prototype operating at 4 GHz implemented in a 0.13 μm CMOS process will be used to illustrate the signaling capabilities of this generator under different test situations.