Boosted Gain of the Differential Amplifier Using the Second Gate of the Dual-Gate a-IGZO TFTs

A dual-gate amorphous InGaZnO
₄
(a-IGZO) thin-film transistor (TFT) has two gate electrodes. The primary gate electrode is at the bottom, and the other is on the top. The drain current of the TFT can be controlled by both the bottom and top gates. This phenomenon provides great flexibility for the circuit design. In this letter, we propose the differential amplifier circuit using the top gate of the dual-gate a-IGZO TFT as an input for positive feedback to boost the gain. It is experimentally verified that the gain of the differential amplifier circuit is increased three times larger than those without the feedback loop.