A WCDMA variable-gain up-conversion mixer using bias-offset technique

This paper presents the design and simulated performance of a novel variable-gain up-converter based on a bias-offset input transconductor. The proposed topology allows the current reuse and reduces the overall transmitter power consumption in wideband code-division multiple access applications. Temperature compensation and decibel-linear characteristic are achieved by means of a control circuit providing a lower than ±1 dB gain error over a 50-dB dynamic range. A 18-dBm output third order intercept, 11.2-dB noise figure, and -50-dB adjacent-channel leakage power ratio are obtained under maximum gain conditions. Circuit simulations are based on a 0.8-μm 46-GHz-f_T silicon bipolar technology.