NEW NON-LINEAR APPROACH FOR THE EVALUATION OF THE LINEARITY OF HIGH GAIN HARMONIC SELF OSCILLATING MIXERS

In this work, the linearity of a high gain Harmonic Self Oscillating Mixer (HSOM) is analyzed. In order to obtain high conversion gain, the working point of the HSOM is established close to a Hopf bifurcation point. The traditional flgures of merit used to characterize the linearity of conventional mixers cannot be directly applied to characterize the behavior of autonomous circuits, because of the in∞uence of the input RF signal power on the autonomous signal parameters. The 1dB compression point and the third order distortion will be analyzed as a function of the harmonic content and maximum gain of the circuit. From the collected data, the optimum harmonic content and the maximum conversion gain of the HSOM can be selected, for a particular application, in order to minimize the output IF signal distortion. Modern microwave communication systems, and specially wireless and portable implementations, have to comply with strict requirements about size, weight, power comsumption and cost. These goals can be achieved by using multi-functional circuits, which enable the implementation of several blocks of the communication system using a reduced number of components. From this point of view, the Harmonic Self Oscillating Mixer (HSOM) is a multi-functional circuit which results an attractive option to be used in front-end stages of microwave