This article proposes a voltage-to-frequency converter (VFC) design using unipolar metal-oxide thin film transistor (TFT) technology. The proposed VFC has an integrator and Schmitt trigger based structure. This structure has the advantages of constant power consumption, full-swing output, and low circuit complexity compared to the early designs. To verify the proposed design, SmartSpice simulation based on a Rensselaer Polytechnic Institute (RPI) model whose parameters are turned to fix the measured characteristics of our indium tin oxide- (ITO-) stabilized ZnO TFTs is carried out. The ITO-stabilized ZnO TFT has a single-gate staggered structure. Its typical field-effect mobility, threshold voltage, on/off current ratio, and subthreshold-slope are 14.5 cm ² /Vs, 0.5 V, $1.2{\mathrm {\times }} 10^{8}$ , and 77 mV/decade, respectively. Simulation results show that the proposed VFC has maximum linearity error less than 1.8%, tuning sensitivity about 1 kHz/V, and power consumption less than $130~{\mu }\text{W}$ even under device variations. These performances are competitive compared to the state-of-the-arts. When configured to an analog-to-digital converter (ADC), 6 bit resolution and 14 S/s sampling rate can be realized. These results indicate that the VFC can find potential applications in flexible large-area low-voltage sensor interfaces for quasi-static signals.

中文翻译：

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使用单极金属氧化物薄膜晶体管的基于积分器和施密特触发器的电压频率转换器

本文提出了一种使用单极金属氧化物薄膜晶体管（TFT）技术的电压至频率转换器（VFC）设计。拟议的VFC具有基于积分器和施密特触发器的结构。与早期设计相比，该结构具有恒定功耗，全摆幅输出和低电路复杂度的优点。为了验证所提出的设计，基于Rensselaer Polytechnic Institute（RPI）模型进行SmartSpice仿真，该模型的参数经过调整以固定我们的氧化铟锡（ITO）稳定的ZnO TFT的测量特性。ITO稳定的ZnO TFT具有单栅交错结构。其典型的场效应迁移率，阈值电压，开/关电流比和亚阈值斜率分别为14.5 cm ² /Vs、0.5 V， $ 1.2 {\ mathrm {\ times}} 10 ^ {8} $ 和77 mV /十倍频。仿真结果表明，提出的VFC的最大线性误差小于1.8％，调谐灵敏度约为1 kHz / V，功耗小于 $ 130〜{\ mu} \ text {W} $ 即使在设备变化的情况下。与最先进的技术相比，这些性能具有竞争力。当配置为模数转换器（ADC）时，可以实现6位分辨率和14 S / s采样率。这些结果表明，VFC可以在用于准静态信号的灵活的大面积低压传感器接口中找到潜在的应用。