Linearity analysis and design optimisation for 0.18 μm CMOS RF mixer

Equations for the 1dB compression point and third-order intermodulation point as a function of circuit and technology parameters are derived using a Volterra series expansion. The linearity analysis for both single- and double-balanced CMOS Gilbert mixers is examined. The relation between the input third-order intercept point and source inductance is studied in depth. The gate to drain overlap capacitance, which is one of the dominant nonlinear elements in a MOSFET, is included in the model. The design methodology to satisfy the mixer noise figure and conversion gain while optimising linearity is summarized. The analytical predictions are verified with the Cadence SpectreRF circuit simulation and experimental data. Good agreement between the model predictions and experimental data is obtained