This paper demonstrates a low-voltage wideband downconverter along with an integrated transformer RF balun using the 2-μm GaInP/GaAs HBT technology. This transformer is a symmetric type and plays a role as a single-to- differential balun. Without the parasitics between the transformer and the substrate, the transformer can work at higher frequencies. This transformer downconverter operates from 1.5 GHz to 14 GHz with around 20-dB conversion gain and 1.8-GHz IF 3-dB bandwidth. The frequency range of the mixing operation is wide and covers the digital video broadcasting via satellite (DVB-S) bands. This mixer hence is useful for DVB-S applications. Since there is no dc voltage drop on the transformer, the voltage supply of the mixer core is only 2.4 V and the current consumption is approximately 8.6 mA. The chip size of the entire mixer is 1 mm × 1 mm while the transformer occupies the estate of 150 μm × 150 μm.