Radio-Frequency Variable Frequency Oscillator

• Main Authors: Wei-Zen Chen, 陳巍仁
• Other Authors: Jieh-Tsrong Wu
• Format: Others
• Language: en_US
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/79120145394351841135

碩士 === 國立交通大學 === 電子研究所 === 82 === Variable-Frequency Oscillators (VFO's), or Voltage Con- rolled Oscillators (VCO's), are widely used in communicationystems. Categorically, oscillators can be divided into twolasses :(1) tuned oscillators which provide nearly sinusoidalutputs; and (2) multivibrators circuits which switch back andorth between two astable states. In this thesis, oscillators implemented with differentechniques, such as LC-sinusoidal oscillators in the firstategory and relaxation type oscillators in the second cate-ory, are presented and compared. Besides, a prototype of ope-ational transconductance amplifier-capacitor (OTA-C) typescillator is also studied and discussed. Most important of all, we invented a novel monolithic ne-ative-resiatance LC VFO' s for use in the microwave range. Its composed of (1) negative impedance converter; (2) variableapacitance converter; and (3) monolithically fabricated induc-ors. By simulation results, the oscillator can operate at fre-uency from 1.7 GHz to 2.25 GHz. This circuit theoreticallyxhibits the benefits of both the two classes of oscillatorsentioned above.