A 1-V Supply a-InGaZnO-Based Voltage Reference With Enhancement- and Depletion-Mode Thin-Film Transistors

In this letter, a voltage reference circuit based on amorphous InGaZnO-based (a-IGZO) thin-film transistors (TFTs) is reported for the first time. Both enhancement-mode and depletion-mode TFTs in the circuit were fabricated by the use of local hydrogen doping. The 1-V reference voltage (
$\text{V}_{\text {REF}}$
) was achieved with an operating voltage ranging from 1.2 V to 5 V, where the line sensitivity of
$\text{V}_{\text {REF}}$
was 0.9%/V and the quiescent consumption was as low as 90 nW. The proposed voltage reference circuit was able to generate complementary- to-absolute temperature coefficients, resulting in stable temperature characteristics. The temperature coefficient (TC) of
$\text{V}_{\text {REF}}$
and
$\text{I}_{\text {REF}}$
was studied experimentally, where the TC of
$\text{V}_{\text {REF}}$
was 2.3 mV/° at a temperature spanning from 27 ° to 77 °.