| As the rapid developments of communication technology and the industry, wireless communication technology have been widely applied to many areas in society, such as mobile communication, Radio Frequency Identification (RFID), Wireless Local Area Network(WLAN) and Global Positioning System (GPS). The monolithic integration in communication technology mainly refers to the integration of radio frequency front-end, and zero-intermediate frequency schemes is the first choice to achieve this integration. However, people have to solve the problems in flicker noise and DC offset accompanying with the integration. The current commutating passive sub-harmonic mixer described in this paper is an effective design to deal with these two problems.In the first place, this paper explicated the principles of superheterodyne receiver and zero-IF receiver and pointed out the advantages and disadvantages of them. Secondly, the introduction of general mixer and its performance index is given and the description of the category and the performance of the mixer is also presented in this paper. Then the operating principle of the current commutating sub-harmonic mixer is derived, and the various methods to realize the sub-harmonic mixer is introduced and the comparisons of these mixers performance are conducted. Further this paper designed the blocks used to realize the sub-harmonic mixer and simulated their performance. Finally, the performance simulation of the whole circuits is implemented .The mixer described in this paper operated at the frequency of 900MHz, applied to the zero-IF RFID reader. By UMC0.18μm process, the performance simulation is implemented in the Cadence Spectre simulator and the main performance indices are as following: operating voltage of 1.8V, operating frequency of 900MHz, the conversion gain of 10dB, 1dB compression point of -10.5dBm , third-order intermodulation intercept point of -2.4dBm, 2LO-RF isolation of -90dB, LO-RF isolation -85dB, noise figure of 16dB. |
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