Dual zero crossing analog-to-digital conversion

We present a new dual zero crossing analog-to-digital converter with a modified Cvetkovic, Daubechies and Logan interpolation algorithm (Cvetkovic, Z. et al., IEEE Computer Soc. Data Compression Conf., p.1-10, 2002). In a conventional zero crossing analog-to-digital converter, the zero crossing times of the input signal minus a reference signal are interpolated. A dual zero crossing analog-to-digital converter incorporates the zero crossings of the reference signal. In a dual zero crossing analog-to-digital converter, the reference signal chain consists of a low resolution analog-to-digital converter followed by a software phase-locked loop based narrow band filter. The reference sine wave signal´s bandwidth allows a narrow band digital filter to create an accurate estimate of the reference signal. The zero crossings of the input signal minus the reference signal trigger a digital latch, thereby capturing the current output value of the estimated reference signal. The zero crossing times are interpolated with a modified Cvetkovic, Daubechies and Logan interpolation algorithm. Simulation results are presented.