Low Cost High Accuracy Stimulus Generator for On-chip Spectral Testing

On-chip testing for analog/mixed signal circuits helps improve reliability of safety-critical systems by enabling infield testing. It also alleviates the problems of increasing test costs. A low-cost high accuracy stimulus generator for on-chip spectral testing is proposed. The generator uses a low-cost DAC which requires minimal design and re-engineering efforts, in conjunction with INL based digital pre-distortion to calibrate its linearity performance. DAC output measurement, DAC INL estimation and DAC linearity calibration are all performed on-chip. Measurement results in 40nm bulk CMOS technology demonstrate that the circuit is capable of producing a rail-to-rail differential signal with THD of -75 dB and SFDR of 79dB. The proposed solution is a major step forward in demonstrating the feasibility of synthesizable built-in-test solutions for high-accuracy embedded analog and mixed signal functions.