Implementation of Active Inductors with Oxide Thin-Film Transistors and Integration into Oscillator Circuits

• Autor(a) principal: Viana, Hugo Filipe Matias
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/138705
• topic: a-IGZO TFT; Active inductor (aL); Simple grounded aL; Cross-couple pair LC-oscillator; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

This work aims to investigate the replacement of passive inductors with active inductors (aLs) using amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFT). The goal of aL is to emulate the inductive behavior associated with passive inductors. The advantage of the former is the small die area, high quality-factor, inductance, and self-resonant frequency tunability. A simple grounded n-type aL was used to replace the inductor in an inductance-capacitance (LC) oscillator. The LC oscillator is constituted by a cross-couple pair and two aLs. The simple grounded aL configuration was used due to a-IGZO being an n-type semiconductor and also owing to its simplicity, being only built with two transistors and two current sources. These factors allied with the lack of a counterpart p- type amorphous oxide semiconductor make this aL a good fit for the proposed work. The oscillator was simulated using metal-oxide-semiconductor field-effect transistor (MOSFET) and TFTs. The former was simulated with a channel length of 1 μm and the latter was simulated with two channel-lengths 10 μm and 20 μm. The MOS technology simulations were used as a proof-of-concept since these have more accurate models. The oscillation frequency (fOSC) and output peak-to-peak voltage swing (Vpp) were analyzed for both technologies. Temperature sensibility, and phase noise were also examined for the MOS technology. The MOS oscillators with three different aLs presented an fOSC between 917 MHz and 2.08 GHz, power consumption from 21 mW to 80 mW, a Vpp of 613 mV up until 1.78 V with a power supply voltage (VDD) of 5V. The maximum phase noise was - 92.86 dBc/Hz at an offset of 1 MHz. A 10 μm a-IGZO TFTs oscillator produced an fOSC of 1.21 MHz and a Vpp of 3.83 V, dissipating 533 μW for a VDD of 10V.