This paper presents a compact transistor model for circuit design in a flexible amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) technology. The presented model is technology specific and builds upon the Verilog-A Rensselaer Polytechnic Institute amorphous silicon TFT (RPI-aTFT) model. On the basis of extensive device characterization, we introduce appropriate new equations and parameters that enable an accurate and efficient behavioral representation of a-IGZO TFTs. In this work, we address the modelling of short channel effects, the scalability for channel lengths from 5 µm to 50 µm, as well as the presence of process variation. Using this model, a Cherry-Hooper amplifier is designed, analyzed, implemented in a flexible a-IGZO TFT technology, and characterized. Finally, to validate the presented transistor model, we compare circuit simulations and measurements of the Cherry-Hooper amplifier circuit. The amplifier provides a voltage gain of 9.5 dB and has a GBW of 7.2 MHz from a supply voltage of 6 V. The simulation using our new compact transistor model resembles the measured characteristics very well. It predicts a voltage gain of 10.4 dB and a GBW of 7.0 MHz.