Only digital technology analog-to-digital converter circuit

In this paper we present a new analog-to-digital converter technique. The basic structure is completely implemented using the digital technology. The proposed ADC circuit is based on the CMOS time to digital converter (TDC) (Watanabe et al., 1993, Arai and Ikeno, 1996 and Watanabe et al., 2003). The ring gate delay is employed as a square wave voltage controlled oscillator (VCO). The VCO operation is based on the changing of the propagation delay time according to supply voltage variation. The proposed fully digital ADC is suitable for sensor applications. The proposed circuit is designed and simulated using 0.5μm CMOS parameters.