Abstract
This paper presents a fully integrated operational amplifier (OPAMP) with positive feedback fabricated in a flexible amorphous indium gallium zinc oxide (a-IGZO) thin film transistor (TFT) technology. The OPAMP is implemented by using a 5 mu m nMOS a-IGZO TFT process, and is operated from a dc supply voltage of 6 V. The circuit relies on positive feedback in the input differential pair to improve gain. The measured open-loop gain is 19 dB over a 3 dB bandwidth of 25 kHz with 70 degrees PM (phase margin). The measured unity-gain frequency, output swing voltage, and dc power consumption are 330 kHz, 3.7 Vpp, and 6.78 mW, respectively. The total chip area of the proposed OPAMP is 4.2x6 mm(2). To the best of our knowledge the proposed amplifier has the highest PM among OPAMPs in TFT technology.