JultikaUniversity of Oulu repository

Abstract

This thesis introduces the linearity analysis of the beamforming phased array receiver. The receiver is consisting of many parallel RF and IF modules. The IF module is working at frequency from 2–4 GHz. The analysis in this thesis is mainly concentrated on how we can take advantage of the parallelism to improve the linearity of both the LNA and the passive mixer. This can be achieved by introducing a minor offset in the output operating point of the parallel blocks, so that the 3rd order nonlinearity coefficients would have opposite signs. This would then cause some cancellation of distortion in the combined output. The analysis shows that the GM stage linearity can be improved up to 30 or 50 dB by slight deviations in the biases of neighbouring GM stages. The previous cancellation needs very good matching so 10–15 dB cancellation is probably a realistic to achieve. The linearity of the passive mixer can be further improved by 10 dB. The linearity analysis is made by building up a polynomial model of the block and then study the first, second and third order coefficients.

Some other design parameters for both the GM stage and passive mixer are analysed such as noise figure, input and output impedance.