Abstract
A voltage-controlled oscillator (VCO) is a key component to generate high-speed clock of mixed-mode circuits and local oscillation signals of the frequency conversion in wired and wireless application systems. In particular, the recent evolution of new high-speed wireless systems in the millimeter-wave frequency band calls for the implementation of the VCO with high oscillation frequency and low close-in phase noise. The effect of the flicker noise on the phase noise of the VCO should be minimized because the flicker noise dramatically increases as the deep-submicron complementary metal-oxide-semiconductor (CMOS) process is scaled down, and the flicker corner frequency also increases, up to several MHz, in the up-to-date CMOS process. The flicker noise induced by the current source is a major factor affecting the phase noise of the VCO. Switched-biasing techniques have been proposed to minimize the effect of the flicker noise at the output of the VCO with biasing AC-coupled signals at the current source of the VCO. Reviewing the advantages and disadvantages reported in the previous studies, it is analyzed which topology to implement the switched-biasing technique is advantageous for improving the performance of the CMOS VCOs.
Highlights
A voltage-controlled oscillator (VCO) is a key component in a frequency synthesizer that generates local oscillator (LO) signals for frequency conversion in a radio-frequency (RF) transceiver [1,2,3]
We review operations, features, and implementation examples of the VCO using the switched-biasing technique as a method to reduce the flicker noise effect generated by the current source
The switched-biasing technique in which the current source of the VCO is modulated with AC signals can reduce the closed-in phase noise of the VCO to minimize the generation of the flicker noise in the source
Summary
A voltage-controlled oscillator (VCO) is a key component in a frequency synthesizer that generates local oscillator (LO) signals for frequency conversion in a radio-frequency (RF) transceiver [1,2,3]. We review operations, features, and implementation examples of the VCO using the switched-biasing technique as a method to reduce the flicker noise effect generated by the current source. The effect of improvement in the phase noise by this technique is examined based on a comparison of the VCO performance obtained by the topologies implementing switched-biasing. It is analyzed whether the switched-biasing technique is useful for generating the millimeter-wave signals, which are increasingly used in various applications. Based on the discussion results, the applicability of the switched-biasing technique for the millimeterwave signal generation, which is mandatory to the high-resolution radar sensors operating at 20 GHz or more, is examined
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have