Fully-differential transimpedance amplifier for reliable wireless communications

The demand of mobile and wireless devices has been continuously growing over the last years, driving the development of new wireless communication systems to provide high data capacity and good accessibility at high data transmission rates. Wireless communication systems must also show high immunity to interference, and in this context distributed systems formed by several remote antenna units (RAU) fed by multi-mode fibers are becoming the preferred solution. At high transmission data rate increases, issues brought by the variability in the fabrication of the circuits and ambient conditions (PVT variations) become more important, and it is necessary to design the systems to minimize their effect. In this work, a fully-differential transimpedance amplifier (TIA) for the receiver in a RAU is presented. The TIA has been designed in a 180-nm RF CMOS technology with a 1.8-V voltage supply and it achieves a bandwidth of 2.5 GHz with a power consumption of 26 mW. To overcome the effect of PVT variations, the TIA features a programmable transimpedance of 20-dB linear-in-dB programmable transimpedance, also increasing the input dynamic range to improve the overall linear range of operation.