The Design Of The Broadband Voltage Controlled Oscillators

With the development of broadband communication technology , the requirement for broadband Voltage Controlled Oscillators(VCO) is more and more. Because of small size, low cost and easy to design,the broadband VCOs based on transistors Occupy very large proportion.This paper introduces the principle of the negative resistance oscillator,and analyses the factors of affected phase noise, and then .discusses the optimization of the phase noise.In order to reduce the phase noise,the ways of select transistors and varactors are given .A 3GHz to 4GHz broadband VCO and related design are presented. The measure results indicate that the VCO reach the ami of the design.