Study Of Co-design Of Radio Frequency Oscillator And Filters

In recent years,with the development of wireless communication,mobile terminals have already evolved into personally intelligent equipments,which have the fundamental function of personal communication as well as other tips like listening to FM broadcast and watching TV.They are also palm computers that ensure a high-speed access to Internet anywhere and anytime. Moreover,the behind 3G system B3G)'s integration of different wireless communication standards make it possible to connect between multi-standards according to need and to switch among different systems seamlessly.Meanwhile,the cost pressure is still rising.The method of co-design can provide a satisfactory solution for this,which focuses on designing and realizing different devices on the same board simultaneously.The merits of different devices can compensate for each other's drawback that can result in a final product with good performance and small dimension.Oscillator is the core of every mobile terminal.This paper proposed a new configuration of negative impedance oscillator using the co-design method to improve the phase noise and harmonic rejection characteristic of the traditional type.The contents of this paper are as follows:First,the configuration of negative impedance oscillator is introduced,the mechanism of phase noise and harmonics in oscillator is described,the harmonic balance method which is employed to simulate oscillator is stated.Second,a new way of transistor modeling as well as a method to extract parameters of transistor is proposed.In this module,factors like bias, temperature and frequency response are taken into consideration.A set of formulae is proposed.Then,traditional negative impedance oscillator is co-designed with bandpass filters.Simulated results for the oscillator before and after co-design proves that the co-design can improve the oscillator's phase noise and harmonic rejection effectively.The oscillator's sensitivity is also analyzed.At last,measured results for oscillator before and after co-design is presented and analyzed,and good agreement with simulated results are obtained.