A Low-Power Fully Dynamic Latched Comparator Using Flexible Oxide TFT Technology

This letter presents a novel low-power, fully dynamic, latched comparator using only n-type, single-gate amorphous-indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) on a $27~\mu $ m thick polyimide substrate. This circuit demonstrates a stable performance up to an input signal frequency of 15 kHz with 1-MHz clock. By employing a pseudo-CMOS bootstrapped load, it achieved an output voltage swing of around 90%, an input-referred offset and noise voltages of 28 mV and 14 mV, respectively from measurements. In addition, it can reliably detect a minimum differential input voltage of 50 mV at a $V_{\mathrm { DD}}$ of 4 V, while consuming only $8~\mu $ W power. Therefore, this design is well-suited in biomedical wearable devices which typically needs low-power.