CMOS frequency mixers for application in third-generation W-CDMA receivers

Two architectures of CMOS frequency mixers---switching and multiplying are presented. For the proposed switching mixer, two pairs of transistors are switched on and off alternatively at the frequency of a local oscillator, generating a square wave. Frequency translation is facilitated by the modulation of the input signal with the generated square wave. In contrast, the multiplier mixer proposed is an active load Gilbert multiplier cell that achieves the frequency translation by multiplying the input signal with a local oscillator signal. The work in this thesis involves a module to be used as the receiving link at the front-end of a third-generation code division multiple access wireless system. The feasibility of such a transceiver on a single chip in a 0.18mum CMOS environment was investigated. Two mixer modules with the aforementioned architectures have been designed, fabricated, and tested using performance measures such as voltage conversion gain and linearity as a guide. Theoretical analyses of conversion gain were verified using software simulations, while the linearity performances were taken experimentally. A discussion is presented to account for discrepancies between the actual results and theoretical expectations such as the lower-than-expected conversion gains, third intercept and 1 dB points for both mixers modules.