A Monolithically Integrated Low-Dropout Regulator Based on a-InGaZnO TFTs With Ultralow Power Consumption

In this letter, a low dropout regulator (LDO) circuit based on an amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) is demonstrated for the first time. The LDO is realized through integrated enhancement- and depletion-mode (D-mode) TFTs, which are manufactured by local NH3 plasma treatment. Two-stage D-mode TFTs and a positive feedback technique are adopted in the error amplifier to enhance the output resistance and voltage gain. The LDO achieves a 1.79 V output across 2.3 V to 7 V supply voltage, with a low dropout voltage of 0.53 V and line regulation of 0.23%/V. It generated a quiescent current of
$0.94~\mu \text{A}$
at a supply voltage of 5 V, and the low power consumption of only
$4.7~\mu \text{W}$
is adopted. A maximum load current of
$176~\mu \text{A}$
and a load regulation of 0.19 mV/
$\mu \text{A}$
is obtained. It owns a power supply rejection ratio (PSRR) of up to 43 dB at low frequencies.