This paper gives a description of a modulator for burst-by-burst carrier frequency hopping in time-division multiple-access (TDMA) systems. The architecture consists of a digital frequency synthesizer/modulator for continuousphase modulations (CPM’s) and a fast frequency settling RF synthesizer consisting of one phase-locked loop (PLL). The performance of the digital frequency synthesizer/CPM m...

A new automatic tuning scheme for continuous-time high-Q-bandpass filters is presented. It is conducted by amplitude comparison at three frequencies generated by an on-chip frequency synthesizer. Theoretical analysis and experimental results are provided. Analysis shows the tuning method is suitable for bandpass filters with 10. A m second-order filter is designed to demonstrate the proposed tu...

This paper presents a new fractional frequency synthesizer architecture and its semi-global stability and robustness analysis tool. The proposed analysis tool takes into account the switched and non linear characteristics of the system components. In order to validate this study, simulation results were obtained with electronics simulators. c opyright © 2005 IFAC

A fully integrated frequency synthesizer that generates multiple frequencies for use in frequency channelized receivers is designed in 0.25μm CMOS technology. Many of the unique features of this receiver have been exploited to design a highly integrated and power efficient multi-output frequency synthesizer including the poly-phase filters. The synthesizer generates 4, 5, 6, and 7 GHz signals w...

A scheme of frequency hopping spread spectrum (FHSS) frequency synthesizer suitable for synthesis of radio-frequency (RF) carrier signal in very high frequency (VHF) band is proposed, implemented and tested. The synthesizer is based on the direct digital frequency synthesis (DDFS or DDS) and phase locked loop (PLL) with dynamic monitoring of varicap’s voltage to reduce switching time. The resul...

Phase locked loops (PLL) are used in almost every communication system. Some of the uses include recovering clock from digital data signals, performing frequency, phase modulation and demodulation, recovering the carrier from satellite transmission signals and as a frequency synthesizer. It is very well known that there are many designs in communication that require frequency synthesizers to ge...

This paper proposes a new stable design strategy for 1bit high order digital ∆Σ modulator for multistandard fractionalN frequency synthesizer. The proposed digital ∆Σ modulator presents simplicity, low power consumption and controls a dualmodulus divider instead of multi-modulus one as in existing ∆Σ fractional-N frequency synthesizer. Simulation results illustrate the ∆Σ modulator good perform...

A 2.4GHz frequency synthesizer is proposed as a part of a low cost RF front end for ISM band applications. The frequency synthesizer employed a new dual loop architecture to improve the settling time, while keeping a fine frequency resolution. With a settling time of 30µs, the frequency synthesizer is able to hop at 2k hop/s with less than 10% overhead. When utilized in a digital wireless syste...