Evaluation of the Beyond-fT Operation of an IGZO TFT-Based RF Self-Mixing Circuit
The objective of this study is to show the potential of amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFT) for designing RF communication systems operating in the GHz regime. For that purpose, the self-mixing operation of in-house fabricated IGZO-TFTs beyond their transit frequency (fT ) is reported. The bottom-gate, top-contact TFTs have an fT of 40 MHz including the device interconnects. A differential RF self-mixing circuit was fabricated to act as an RF detector and frequency doubler. The detector shows a peak voltage responsivity (RV ) and a minimum noise equivalent power (NEP) of 445 V/W and 0.1 nW/√Hz at 50 MHz and 2 V/W and 30 nW/√Hz at 1 GHz respectively, at a chopping frequency of 28 kHz. As a frequency doubler, the circuit can generate a second harmonic output voltage up to −36 dBV for an 8 dBV RF input voltage at 100 MHz.
This document is an accepted manuscript version that has been published in final form in IEEE Microwave Wireless and Component Letters. https://doi.org/10.1109/LMWC.2018.2886068
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