A High-Gain CMOS Operational Amplifier Using Low-Temperature Poly-Si Oxide TFTs

A high-performance CMOS operational amplifier (op-amp) has been demonstrated with the low-temperature poly-Si oxide (LTPO) thin-film transistors (TFTs). The p-type TFT exhibits the maximum field-effect mobility of 80 cm²/V.s and subthreshold swing (SS) of 0.7 V/decade. The n-type amorphous indium-gallium-zinc oxide (a-IGZO) TFT exhibits the SS of 0.3 V/decade and the mobility of 11.5 cm²/V.s. The op-amp consisting of 13 TFTs functions in two stages. It exhibits a high voltage gain of 50.7 dB, a cutoff frequency of 200 kHz, a unit gain frequency of 7 MHz, and a very high gain-bandwidth product of 68.5 MHz. The first LTPO CMOS op-amp with low-power consumption of 0.6 mW demonstrates the potentiality of this emerging technology.