The Design Of S Band Small Step Into Frequency Source

Frequency synthesizer is the key modules in communication and mearsuring system. The indicators of frequency synthesizer extently decided the function of communication system and measuring equipment would realized or not. Frequency synthesis technique started in the 1930 s, and had made rapid development. But as the development of technology, higher requirement of frequency synthesier was put forward.Accompanied by the coming forthd and developing of new frequency synthesis techniques, the initial direct frequency synthesis developed to indirect, direct digital and mixed frequency synthesis. Our country’s frequency synthesis technique was originated in the 1970 s, and has made some achievements.But compared with Europe and the america the key technology still has large gap.The main purpose of this thesis is to develop a s-band step into frequency source by applying the hybrid frequency synthesis technique. The main works of this thesis include the followings:1. This thesis expounds the phase-locked type(PLL) frequency synthesis technique’s basic theory and indicators of noise, trapping, andtracking, also analysis the math model of the phase locked loop phase noise and the VCO oscillating principle.2. This thesis expounds the basic principle of direct digital frequency synthesis(DDS) technique and analysis its reasons of the poor stray index.3. This thesis analysis the commonly used hybrid frequency synthesis technique’s scheme, and select the scheme to realize frequency source, and carries on the system that if it can be realized.4. Based on the principle of feedback oscillator to design the S band VCO that frequency is 2.0GHz-2.2GHz.5. By analyzing and designing the DDS and PLL circuit and, and simulating the whole system, this thesis design the s-band step into frequency source, finally. Phase noise is better than-95dBc/Hz @ 10 KHz, frequency step is 5Hz.