A scalable time-domain biosensor array using a capacitor-less CMATC and logarithmic cyclic time-attenuation-based TDC with discharge acceleration for high-spatial-resolution bio-imaging

This paper presents a time-domain biosensor array that uses a capacitor-less current-mode analog-to-time converter (CMATC) and a logarithmic cyclic time-attenuation-based time-to-digital converter (TDC) with discharge acceleration. By combining the exponential function of the CMATC and the logarithmic function of the proposed TDC, linear input-output characteristics are provided. The TDC cyclically attenuates the input time difference to enable logarithmic time-to-digital conversion. In emerging high-speed operations, the discharge acceleration signal is employed for time attenuation. The timedomain property enables bio-imaging at a high spatial resolution and large scale while maintaining scalability. The measurement results from a 0.25-pm test chip exhibited linear input-output characteristics. Finally, we performed potentiometric measurements using a CMOS FET-based redox potential sensor.