VCO Design Tutorial: “How to design RF Circuits” – Oscillators
This Articles goes over the Design of a Clapp oscillator, using a  varactor tuned ceramic coaxial resonator for voltage control of the output frequency. The frequency under consideration will be around 1.4 GHz. Includes some Small & Large Signal Design Techniques.

By Andrew Dearn

Understanding VCO Concepts
Fundamentals of Oscillator design with various example circuits. 

VCO Concepts from Mini Circuits

Voltage Controlled Oscillators
This Articles discusses various aspects of VCO Design such as Input Impedance Calculation of negative resistance oscillators, Small Signal Circuit Models, Wideband VCOs Vs Narrowband VCOs, Phase Noise, Oscillator Noise and more…

Fundamentals of VCOs from Synergy Microwave

The Design Of Single-Ended & Differential MMIC VCOs

This paper describes design techniques for both single-ended and differential VCOs, with examples shown fabricated in GaAs MMIC processes. The potential uses and advantages of the differential over the conventional single-ended approach are discussed.

By Andy Dearn and Liam Devlin, Plextek Ltd.

Advanced VCO Design using Ansoft Designer

This Article goes over the design of a VCO using Ansoft Designer. The VCO has an oscillation frequency of 1800 MHz +/- 30 MHz, an output power of 4 dBm, a voltage supply of 3 V and a Current consumption of 8 mA.

By Moriaki Ueno from AnsoftJapan

Enhancement of VCO Linearity and Phase Noise by Implementing Frequency Locked Loop

This paper investigates the implementation of a Frequency Locked Loop (FLL) over a VCO. The FLL decreases phase noise and linearizes the transfer function. The FLL is fabricated on a 0.35um BiCMOS process and has an operation frequency of 10 GHz.

By Emre Ayranci , Kenn Christensen, Pietro Andreani From The Center for Physical Electronics, Oersted.DTU, Kgs. Lyngby, Denmark

Low-Phase-Noise CMOS VCO with harmonically tuned LC Tank

A low phase noise VCO has been demonstrated using a harmonically tuned LC Resonance tank. The VCO has an operating frequency of 1 GHz and a Phase noise of -111 dBc/Hz at 100 KHz offset. The VCO has been fabricated on a 0.35um CMOS process.

From The Department of Electronic and Electrical Engineering, Microwave Application Research Center, Pohang University of Science and Technology, Korea

VCO Phase Noise
This Articles Discusses VCO phase noise in detail.

Application Note from Mini Circuits