A high-speed, direct up-conversion transmitter for cable applications using very linear 0.5 µm "Cold" CMOS mixers

This paper presents a CMOS, very linear, quadrature direct up-conversion transmitter. All distortion and intermodulation spurious signals have been measured to be lower than -50dBc. Up to -60dBc mirror frequency suppression has been achieved. The measurements have been performed without any additional tuning or trimming. The excellent linearity performance has been obtained by exploiting the superior linear behaviour, the low LO feedthrough and the conversion gain insensitivity to the VTmatching of CMOS transistors biased in the linear region with a 0V mean drain-source voltage:"Cold CMOS transistors". The high quadrature accuracy required to obtain this very low mirror signal, has been obtained using a 6^thorder polyphase circuit. The external output load is driven by a true single-ended output stage. The transmitter\´s operating voltage is 3V. The chip has been processed in a standard 0.5µm CMOS technology.