Analysis and design of a regenerative differential voltage-controlled oscillator for high frequency integrated circuit applications

An investigation into the feasibility of designing a monolithic high frequency voltage controlled oscillator is performed. With design constraints of an oscillator Q between 5 and 10 and minimal chip area, the resonant LC tank and negative resistive cross coupled differential amplifier circuit is analyzed and design guidelines are developed. Analysis of the circuit encompasses both linear and non-linear modes of operation of the circuit, predicts the fundamental frequency of oscillation, and highlights design limitations for the resonant elements in terms of meeting the Q specifications at higher frequencies. Experimental results on a fixed frequency version of the VCO circuit yielded good agreement with theoretical analysis. For the parameters tested, the error was on the order of 10% in most cases