To our knowledge, this paper presents the first high-gain amplifiers fabricated in flexible self-aligned amorphous indium gallium zinc oxide (a-IGZO) thin-film-transistor (TFT) technology. For the common source amplifier applying positive feedback a voltage gain of 17 dB, a bandwidth of 79 kHz and a DC power of only 0.76 mW were measured. For the cascode amplifier a voltage gain of 25 dB voltage gain, a bandwidth of 220 kHz and a DC power of 2.32 mW were measured. The simulations based on a RPI-aTFT model are compared with measurements. The chip areas are 8 and 10 mm2, respectively.