An on-glass a-IGZO TFT operational amplifier for local voltage regulation in display driving systems

This work presents an on-glass amorphous indium-gallium-zinc oxide thin-film transistor (a-IGZO TFT) operational amplifier to achieve an integrated local voltage-regulation for reference-voltage stabilization in display driving systems. The fabricated op-amp adopts compact n-type-only two-stage architecture to reduce circuit complexity and internal high-impedance nodes for closed-loop operation. Under ± 15 V supply voltages, the measured op-amp exhibits a voltage gain of 35.5 dB, a cut-off frequency of 5.8 kHz, and a unit-gain frequency of 39 kHz. To examine closed-loop controllability, the op-amp was combined with external pass/load components in a prototype regulation setup. The measured output voltages were 1.82 V, 3.79 V, and 5.55 V for reference voltages of 2 V, 4 V, and 6 V, respectively. Circuit-level simulations were further used to analyze line-ripple suppression and load-transient recovery. The results indicate that a-IGZO TFT op-amps can be useful analog building blocks for low-current local voltage regulation in system-on-glass display platforms.