AND JEFFREY L. CUTCHER Motorola Inc. Plantation, FL Fractional-N synthesizers are highly desirable in communication systems because of their high frequency resolution output. This resolution is made possible by dithering the divide value using the output of a sigma-delta modulator. A typical sigma-delta fractional-N frequency synthesizer is shown in Figure 1. The tri-state phase frequency detec...

A femtosecond laser-based optical frequency synthesizer is referenced to an optical standard, and we use it to demonstrate the generation and control of the frequency of electromagnetic fields over 100 terahertz of bandwidth with fractional uncertainties approaching 1 part in 10(19). The reproducibility of this performance is verified by comparison of different types of femtosecond laser-based ...

Current-mode-logic circuits play an important role in the design of CMOS frequency synthesizers for modern wireless digital communication systems. They provide the building blocks for frequency dividers with input frequencies in the range of the desired carrier frequencies. In this communication we estimate the upper limit frequency as a function of the gate length using voltage swing considera...

Frequency synthesizers find use in all high frequency applications such as communications, radar, digital communications, electronic imaging and spectroscopy [1]. There are three main techniques commonly used 1) PLL synthesizers based on a feedback mechanism to lock to a reference frequency. The popularity of the PLL is due to their extended tracking range and low cost. 2) Direct analog frequen...

Introduction: Fractional-N frequency dividers allow PLL Synthesizers to have frequency resolutions finer than the reference frequency. However, there are two disadvantages in a fractional-N divider, namely, fractional spurs generation and frequency range limitation. A fractional-N divider generates fractional spurs due to the fixed pattern of the dual-modulus divider [1]. The frequency range of...

A methodology is presented for predicting the jitter performance of a PLL using simulation that is both accurate and efficient. The methodology begins by characterizing the noise behavior of the blocks that make up the PLL using transistor-level simulation. For each block, the jitter is extracted and provided as a parameter to behavioral models for inclusion in a high-level simulation of the en...

We report on a compact optical frequency comb, operating in the wavelength range from 670 to 1500 nm, based diode-pumped low-noise femtosecond Yb:CALGO amplified laser system. Both carrier-envelope offset and repetition rate are phase-locked reference synthesizers. A full characterization of terms stability, phase noise analysis, beating against single-frequency non-planar ring oscillator Nd:YA...