A Study on Linearity of Mixers for Homodyne Receivers

In this thesis the linearity characteristics of passive mixers for wide band homodyne receivers are studied. The circuits are simulated using Cadence Spectre with models from a 65 nm RF/Analogue CMOS process. Linearity dependence of common mode voltage, load impedance, switch network arrangement and local oscillator drive circuitry is studied and analysed. The thesis also covers methods for the linearisation of baseband ampli ers. Three linearised ampli ers for frequencies down to DC are demonstrated. The linearised ampli ers are then used in passive mixer circuits to analyse the e ects of baseband linearity improvement on complete mixer linearity. The results from this test show that improving the open loop linearity of the baseband ampli er has an appreciable impact on mixer linearity. The work presented in this thesis was performed at Ericsson AB in Kista, Stockholm, Sweden during the period January to June 2013.