A 14GHz Cascade Differential-Capacitor-Based DCO with Resistor-Biased Buffer

Abstract

A 14GHz digitally controlled oscillator (DCO) is proposed for all-digital phase-locked loop (ADPLL). With a cascade differential-capacitor array, the resolution of DCO is enhanced, which leads to a decrease in quantization noise, while area cost and substrate noise are also significantly reduced. In addition, a resistor-biased DCO output buffer is used to cut down phase noise by eliminating flicker and thermal noise conventional current-mirror structure brings. The proposed DCO is designed in 14nm FinFET process, achieving a phase noise of -110dBc/Hz at 1MHz offset and a frequency resolution of 7kHz. DCO operates in a frequency range of 17.8%, with a 0.017 mm 2 core area. The DCO consumes 6.3mW from a 0.8V supply voltage.

A 3.83–5.55 GHz high frequency resolution DCO with optimized switched‐capacitor ladder and low‐coupled eight‐shaped transformer

“…This means that the proposed structure can reduce the SC resolution ΔC by a factor of 2 12 , which greatly improves the tuning accuracy.…”

“…Figure 1A shows the first stage of the cascaded differential SC array proposed in Yanchi et al 12 Each stage consists of two , two , and 15 SC units. and are capacitors connected in series and parallel in the SC units, respectively.…”

“…The single‐stage differential SC array proposed in Yanchi et al 12 (A) and proposed in this paper (B).…”

“…Another research in DCO adds coarse, medium, and fine-tuned switched-capacitor (SC) arrays to the traditional inductorcapacitor oscillator to achieve high resolution. [11][12][13][14][15][16][17][18] Luong presented a 54.79-63. 16 GHz DCO using an exponentially scaling SC ladder.…”

“…The measured resolution is 300 kHz, and the phase noise is less than −90.7 dBc/Hz, 11 whereas the DCO is still sensitive to substrate noise. To solve this problem, Yanchi 12 proposed a cascaded differential capacitor array to achieve low phase noise while significantly reducing substrate noise. The DCO provides a phase noise of −110 dBc/Hz, a frequency resolution of 7 kHz, and a frequency range of 17.8%.…”