The evolution of CMOS technology demands new approaches to implement radio-frequency integrated circuits. This paper presents two digital-intensive frequency synthesizers implemented in 65-nm CMOS: a digital period frequency synthesizer and an all-digital phase-locked loop. The experimental circuits cover frequency ranges of 0.1 4.3 GHz and 2.7 6.1 GHz.

The main function of a frequency synthesizer is to deliver a stable and clean signal. However, many applications require not only a fixed frequency signal but also various modulation functions ranging from simple pulse, amplitude, frequency and phase modulation to complex digital modulation formats. Although modulators are usually realized as external devices, they can also be incorporated into...

In this article the contribution of the digital RD modulator in fractional frequency synthesizers is explored. Due to the circuit’s non linear behavior, the spur tones generated by the digital RD modulation degrade the synthesizer’s phase noise even in regions where the charge pump noise is dominant. A new method to dither digital MASH RD modulators for fractional frequency synthesizers is prop...

Historically, physical models have led to prohibitively expensive synthesis algorithms, and commercially available synthesizers do not yet appear to make use of them. These days, most synthesizers use either processed digital recordings (\sampling synthesis") or an abstract algorithm such as Frequency Modulation (FM). However, as computers become faster and cheaper, and as algorithms based on p...

-The proposed paper shows existing problems in VCO’s and synthesizers due to the nonlinearities in the active devices and external integrated circuits. This paper proposes a design guidance on how to minimize such effects in oscillators by using nonlinear, rather than linear, tools. In synthesizers, the reference frequency and its harmonics will mix with the output frequency in the phase detect...

The aim of this paper is to minimize output phase noise for the pure signal synthesis in the frequency synthesizers. For this purpose, first, an exact mathematical model of phase locked loop (PLL) based frequency synthesizer is described and analyzed. Then, an exact closed-form formula in terms of synthesizer bandwidth and total output phase noise is extracted. Based on this formula, the phase ...