This paper proposes a digital-to-time converter (DTC)-assisted fractional-N wide-bandwidth all-digital phase-locked loop (ADPLL) with a fine-resolution time-to-digital converter (TDC). The TDC employs a two-channel time-interleaved time-domain register with an implicit adder/subtractor realizing an error-feedback topology. Such an error-feedback unit of a first-order Δ Σ -TDC can be cascaded as a multi-stage noise shaping configuration to achieve higher-order noise-shaping and, thereby, low in-band phase noise (PN) of the ADPLL. A digitally controlled oscillator with a transformer and a pair of cross-coupled NMOS amplifiers exploits magnetic and capacitive coupling to achieve nearly an octave frequency coverage, i.e., 1.73-3.38 GHz (after a ÷2 division). Fabricated in 40-nm CMOS, the ADPLL achieves better than -110-dBc/Hz in-band PN and occupies an active area of 0.5 mm². With a 50-MHz reference clock, a 2-GHz output RF clock, and a loop bandwidth of 800 kHz, this prototype achieves 420-fsrms jitter, integrated from 1-kHz to 30-MHz offset, while drawing 10.7 mW.

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This brief presents a two-dimensional (2-D) Vernier time-to-digital converter (TDC) which uses two 3-stage gated ring oscillators (GROs) in the X/Y Vernier branches. The already small Vernier quantization noise (∼10.6 ps) is improved by the first-order noise shaping of the GRO. Moreover, since all the delay differences between the X and Y phases can be used (rather than only the diagonal line of the one-dimensional architecture), the intrinsic large latency time of the Vernier architecture is dramatically reduced. The TDC is implemented in a 65-nm CMOS process and consumes 2.3 mA from 1.0 V. The measured total noise integrated over a bandwidth of 1.25 MHz yields an equivalent TDC resolution of 2.2 ps, whereas the average latency time (within 2 ns) is less than 1/6 of that in a standard Vernier TDC.

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We present a digital-to-time converter (DTC)-assisted fractional-N wide-bandwidth all-digital PLL (ADPLL). It employs a MASH ΔΣ time-to-digital converter (TDC) to achieve low in-band phase noise, and a wide-tuning range digitally-controlled oscillator (DCO). Fabricated in 40nm CMOS, the ADPLL consumes 10.7 mW while outputting 1.73 to 3.38 GHz (after a ÷2 division) and achieves better than -109 dBc/Hz in-band phase noise and 420fsrms integrated jitter.@en