In this paper, the flicker noise properties of bottom-gate ESL structured amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) from two different technologies have been studied and modeled. Model development is carried out by adapting the Unified Model parameter Extraction Method (UMEM), developed for parameter extraction and compact modeling of TFT devices, and the unified 1/f noise model. Furthermore, comparative study of device figures of merits is performed to point out the device performance enhancements that the different fabrication technologies have brought about. It is found out that both devices have low deep state density, whereas the second device demonstrated higher performance in terms of carrier mobility and subthreshold slope. Both the DC and noise models are validated by matching them against experimental data obtained in different regimes of device operation.