Voltage-controlled oscillator

About: Voltage-controlled oscillator is a research topic. Over the lifetime, 23896 publications have been published within this topic receiving 231875 citations. The topic is also known as: VCO.

Microwave MEMS-based voltage-controlled oscillators

Abstract: A microwave voltage-controlled oscillator (VCO) based on coupled bonding wire inductors and microelectromechanical system (MEMS)-based variable capacitors for frequency tuning is demonstrated in this paper. The MEMS-based variable capacitors were fabricated in a standard polysilicon surface micromachining technology. The variable capacitors have a nominal capacitance of 1.4 pF and have a Q factor of 23 at 1 GHz and 14 at 2 GHz. The capacitance is variable from 1.4 to 1.9 pF as the tuning voltage is swept from 0 to 5 V. The VCO, fabricated in a 0.5 /spl mu/m CMOS technology, was assembled in a ceramic package where MEMS and CMOS dice were bonded together. The oscillator operates at 2.4 GHz, achieves a phase noise of -122 dBc/Hz at 1 MHz offset from the carrier, and exhibits a tuning range of 3.4%.

Multi-loop control for quasi-resonant converters

Abstract: A multiloop control scheme for quasi-resonant converters (QRCs) is described. Like current-mode control for pulse width modulation (PWM) converters, this control offers excellent transient response and replaces the voltage-controlled oscillator (VCO) with a simple comparator. In this method, referred to as current-sense frequency modulation (CSFM), a signal proportional to the output-inductor current is compared with an error voltage signal to modulate the switching frequency. The control can be applied to either zero-voltage-switched (ZVS) or zero-current-switched (ZCS) QRCs. Computer simulation is method applied to a ZCS buck QRC. A circuit implementation is presented that allows multiloop control to be used on circuits switching up to 10 MHz. This circuit requires few components and produces clean control waveforms. Experimental results are presented for zero-current flyback and zero-voltage buck QRCs, operating at up to 7 MHz. Good small-signal characteristics have been obtained. >

Large-signal analysis of MOS varactors in CMOS -G/sub m/ LC VCOs

Abstract: MOS varactors are used extensively as tunable elements in the tank circuits of RF voltage-controlled oscillators (VCOs) based on submicrometer CMOS technologies. MOS varactor topologies include conventional D = S = B connected, inversion-mode (I-MOS), and accumulation-mode (A-MOS) structures. When incorporated into the VCO tank circuit, the large-signal swing of the VCO output oscillation modulates the varactor capacitance in time, resulting in a VCO tuning curve that deviates from the dc tuning curve of the particular varactor structure. This paper presents a detailed analysis of this large-signal effect. Simulated results are compared to measurements for an example 2.5-GHz complementary -G/sub m/ LC VCO using I-MOS varactors implemented in 0.35-/spl mu/m CMOS technology.

Wireless power feeder, wireless power receiver, and wireless power transmission system

Abstract: Power is fed from a feeding coil L2 to a receiving coil L3 by magnetic resonance. A VCO 202 alternately turns ON/OFF switching transistors Q1 and Q2 at a drive frequency fo, whereby AC power is fed to the feeding coil L2, and then the AC power is fed from the feeding coil L2 to the receiving coil L3. A phase detection circuit 114 detects a phase difference between the current phase and voltage phase, and the VCO 202 adjusts the drive frequency fo such that the phase difference becomes zero. When load voltage is changed, the detected current phase value is adjusted with the result that the drive frequency fo is adjusted.