A High Performance Operational Amplifier Using Coplanar Dual Gate a-IGZO TFTs

Abstract

We fabricate an operational amplifier (op-amp) composed with the coplanar amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The circuit consisted of 19-TFTs and designed on a glass substrate in both dual gate (DG) and single gate (SG) structure for performance evaluation. Having the yield of a total voltage gain (A v ) of 23.5 dB, a cutoff frequency (f c ) of 500 kHz, a unit gain frequency (f ug ) of 2.37 MHz, gain-bandwidth product (GBWP) of 7500 kHz, a slew rate (up/down) of (2.1/1.2) V/µs, and a phase margin (PM) of 102 • at a supply voltage of ±10 V, the fabricated DG TFT op-amp demonstrates good performance among all a-IGZO-based literature. INDEX TERMSCoplanar a-IGZO TFTs, dual gate, single gate, operational amplifier (op-amp).

High gain operational amplifier and a comparator with a‐IGZO TFTs

“…From the frequency response of the circuit, unity gain frequency () of 215 kHz is reported which is higher than [9, 22–24]. However, a higher value of is reported in [8, 11] due to advancement in technology and fabrication process. While [8] uses dual gate technology, the circuit reported in [11] employs a self‐alignment fabrication process, which decreases overlap capacitances of the device.…”

“…However, a higher value of is reported in [8, 11] due to advancement in technology and fabrication process. While [8] uses dual gate technology, the circuit reported in [11] employs a self‐alignment fabrication process, which decreases overlap capacitances of the device. Furthermore, the circuit reported in [11] employs aluminium oxide () as gate insulator, which offers a high dielectric constant and hence capable of operating at lower power supply voltage.…”

“…Different works have already been reported viz. amplifiers [6][7][8][9][10][11] and comparators [12,13] using a-IGZO TFTs. However, for amplifiers, the power consumption is significantly high with limited voltage gain.…”

Significant Performance and Stability Improvements of Low-Temperature IGZO TFTs by the Formation of In-F Nanoparticles on an SiO2 Buffer Layer

“…It is noted that the quality of SiO 2 depends on its substrate process temperature; the density and leakage through SiO 2 and electrical breakdown voltage could be improved by increasing the deposition temperature of SiO 2 . The buffer SiO 2 of coplanar structures and the gate dielectric SiO 2 of back-channel-etch (BCE) structures are usually deposited at 300 to 400 • C by plasma-enhanced chemical vapor deposition (PECVD) for display applications [7,8]. The coplanar structure of IGZO TFTs has the advantage of negligible overlap capacitance between the gate and source/drain electrodes, and thus, the RC (resistance-capacitance product) delay can be remarkably reduced for display applications [5][6][7] [9][10][11].…”

Low-voltage and fully flexible analogue/digital mixed-signal circuits based on carbon nanotubes for epidermal sensor applications

“…The Monte Carlo method was used for the circuit simulation to account for device variability. The Monte Carlo method ( Figure 2i We compared the performance of the present CNT op-amp with those of various differential amplifiers [32][33][34][35][36][37][38][39] and op-amps: [40][41][42][43][44][45][46] single-polarity TFTs on a flexible substrate [32][33][34][35][36][37][38][39][40][41][42] or glass substrate [43][44][45][46][47] and with oxide semiconductors, [32][33][34][40][41][42][43][44][45]47 organic semiconductors, [35][36][37][38][39] or amorphous Si 46 . The prese...…”