Phase-locked Loop Applications Research Articles

Korišćenje fazne petlje za potiskivanje prostoperiodične smetnje kod sistema sa direktnom sekvencom

Korišćenje fazne petlje za potiskivanje prostoperiodične smetnje kod sistema sa direktnom sekvencom

Linear Drive Systems and their Related Technologies. Application of Phase-Locked Loops to Magnetic Suspension Systems.

This paper demonstrates that phase-locked loop techniques can be applied to stabilize an active magnetic suspension system with displacement sensors of frequency type. Feeding back the difference of frequency in addition to PLL control is proposed to speed up the process of phase-locking. It is also pointed out that the self-sensing magnetic suspension is realized with a hysteresis amplifier, which is a switching power amplifier whose switching frequency varies with the position of the suspended object. In the experiments, a PLL control feeding back the switching signal of a hysteresis amplifier is successfully implemented in a magnetic suspension system with a conventional PD controller. The measured responses to step and sinusoidal disturbances show that an integral feedback arises automatically in the magnetic suspension system because the control input is produced from the difference in phase between the reference and feedback signals in the PLLs.

Cell-based fully integrated CMOS frequency synthesizers

A family of standard cells for phase-locked loop (PLL) applications is presented. The applications are processed using a 1.5 /spl mu/m, n-well, double-polysilicon, double-layer metal CMOS process. Applications include frequency synthesis for computer clock generation, disk drives, and pixel clock generators for computer monitors, with maximum frequencies up to 80 MHz. The synthesizers require no external components since the loop filter and oscillator are on chip with the phase frequency detector and the charge pump. Special voltage and current reference cells are discussed. Analysis of noise sources in the PLL demonstrates the need for reducing the phase noise of the system. A low phase noise is achieved through supply rejection techniques and by placing the oscillator in a high-gain feedback loop to minimize its noise contributions. Laboratory measurements of completed silicon show synthesizers with exceptionally linear gain, as well as transient responses and phase noise similar to predicted results. >

A highly stable VCO for application in monolithic phase-locked loops

The characteristics of the voltage-controlled oscillator (VCO) are generally the most important in determining the overall system performance of phase-locked loops. A new VCO is described which achieves a better combination of temperature stability, speed, and power dissipation than could previously be obtained in a monolithic integrated circuit.