A 2.62 MHz 762 µW cascode amplifier in flexible a-IGZO thin-film technology for textile and wearable-electronics applications

Metal oxide semiconductor thin-film transistors for flexible electronics

“…42(a) and 43). 81,106,113,212,213,305,313,[318][319][320][321]323,329 The dynamic performance of a common-source amplifier (and of any other type of amplifier) is evaluated using the so-called Bode plot (amplitude and phase) shown in Figs. 46(a) and 46(b), which is a standard format for plotting the circuit frequency response.…”

“…212 whereas the largest occupied area is of 9.83 mm 2 (also shown for an operational amplifier constituted by 13 IGZO TFTs). 313 To date, the variety of flexible metal oxide semiconductor-based analog circuits reported ranges from single-to multiple-stage (e.g., commonsource, 113 transimpedance, 329 differential, 80,323 cascode, 318,321 operational, 212,313 and Cherry-Hooper 319 ) amplifiers, which at the same time often also include biasing circuits like current mirrors. 212 Similarly, new analog functions such as antenna channel select circuits, 337 X-ray readout circuits, 338 and digital to analog converters (DAC) 339 have been implemented recently.…”

“…The cascode amplifier by Shabanpour et al consumes 762 lW power during standard operation. 318 A second version of this cascode amplifier shows a higher DC gain (25 dB) at the cost of a lower cut-off frequency of 220 kHz, consuming 2.32 mW power at 6 V. 321 Even more TFTs (13 IGZO devices) have been utilized in an operational amplifier with a GBWP of 31 kHz and an open-loop gain G OL of 22.5 dB, resulting in a f c ¼ 5.6 kHz. 313 Furthermore, this operational amplifier consumes 160 lW power during standard operation.…”

A threshold voltage and drain current model for symmetric dual-gate amorphous InGaZnO thin film transistors

“…is the flat-band voltage in which W m and χ IGZO are gate metal work function and electron affinity of a-IGZO. In subthreshold region, most of the free carriers are trapped in tail states, thus we only consider the ionized trap states in (1) with (5) and (6), and integrate (1) from 0 to t IGZO /2 once and twice to obtain…”

“…Amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) are becoming preference for high-quality and large-size display applications, for their reasonably high electron mobility (>10 cm 2 • V −1 • s −1 ) even though fabricated at room temperature [1], good device uniformity, and relatively low fabrication costs [2]. Moreover, the high optical transmittance and flexibility of a-IGZO films have enabled various novel electronic applications based on a-IGZO TFTs, such as flexible transparent displays [3], virtual reality displays [4], transparent RFID logic chips [5], and wearable electronics [6]. However, the electrical stability, especially bias stability under illumination evaluated mainly by threshold voltage shifts turns out to be a great concern [7][8][9].…”