3. Wideband Voltage Controlled Oscillator

In this chapter, we explore techniques to increase the tuning-range of VCOs while maintaining adequate phase noise and power dissipation performance over the tuning range. Two popular oscillator architectures: LC tank based, and ring based, are considered for SDR signaling and spectrum scanning applications. Of these, LC tank VCOs are traditionally well suited for their superior phase noise and low power consumption at radio frequencies, and are therefore the preferred choice. However, LC tank VCOs are notorious for their lower tuning range as compared to ring oscillators. In this work, we select the LC tank oscillator and devise a scheme based on switched inductors, and capacitor array optimization, to extend the desirable power and phase noise properties of LC VCOs over a wide tuning range for use in SDR signaling (and sensing) applications.