Mostly-digital design of sinusoidal signal generators for mixed-signal BIST applications using harmonic cancellation

This work proposes a novel approach for the design of high-quality on-chip sinusoidal signal generators using digital circuitry. The proposed generation technique is based on a simple digital shift-register that provides a set of phase-shifted versions of a digital square-wave signal. These square-wave signals are conveniently combined using a harmonic cancellation strategy to yield a spectrally pure sinusoidal output signal. The proposed strategy allows cancelling low-frequency harmonics close to the fundamental component of the generated sinusoidal signal, while a simple first order low-pass filter is used to attenuate higher order harmonic components. A simple one-shot calibration strategy is also presented in order to compensate the effects of the main non-idealities affecting the dynamic linearity of the generator. Statistical behavioral simulations are provided to demonstrate the feasibility of the proposed generator.