In-Panel 31.17dB 140kHz 87µW Unipolar Dual-Gate In-Ga-Zn-O Charge-Sense Amplifier for 500dpi Sensor Array on Flexible Displays

In this paper a charge sense amplifier (CSA) using a 5µm In-Ga-Zn-O transistor technology on 15µm thick flexible substrate is presented for readout of a 500dpi fingerprint sensor array targeting direct integration with active matrix organic light emitting displays (AMOLED). The CSA achieves a linear input range of 0.8V for rail to rail output at V DD =15V. The CSA comprises of a high gain and stable dual-ended output dual-stage amplifier. The n-type load is driven by a dual-stage buffer and start-up circuit to increase the performance and ensure stability. The amplifier operates down to 6V supply voltage. It achieves 31.17dB DC-gain, 140kHz gain-bandwidth, 53° phase margin and dissipates 87µW at 15V. The footprint of the CSA is 0.3mm 2 and enables 1fps readout of 1 megapixel 500dpi sensor array.