Mixer Performance Research And Development Of A Programmable Signal Source

The noise and linearity of mixer were analyzed, the design method and realization of the program-controlled direct digital synthesis signal generator were summarized.In the sections about mixer, first, two realizing methods of mixer, its major performance parameters, the design and optimization flow of the double balanced mixer were explained briefly. Second , the noise of double balanced mixer was analyzed, which involved analysis of low frequency flicker noise and high frequency thermal noise. The improvement measure on the noise performance was deduced. In the end, the linearity improvement on the transconductance stage of the double balanced mixer was researched. In order to got the detail information on circuit's linearity improvement by using negative feedback, its general expressions on third-order intermodulation were concluded, and a new type of mixer circuit with its improved linearity was analyzed.In the sections about signal generator, the realizing project was brought forward based on its specification. The major chip and its function, the realizing circuits of the signal generator and its SCM control programs were depicted. In the end, the performance test and analysis of the signal generator were given.