As Nature Chemical Biology approaches its third decade we asked a collection of chemical biologists, “What do you think are the most exciting frontiers or the most needed developments in your main field of research?” — here is what they said.

This article proposes a power-efficient highly linear capacitor-array-based digital-to-time converter (DTC) using a charge redistribution constant-slope approach. A fringe-capacitor-based digital-to-analog converter (C-DAC) array is used to regulate the starting supply voltage of the constant discharging slope fed to a fixed-threshold comparator. The DTC operation mechanism is analyzed and design tradeoffs are investigated. The proposed DTC consumes merely 31 μW from a 1-V supply when clocked at 40 MHz, while achieving a fine resolution of 148 fs over a 9-bit range. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) are 0.96/1.07 LSB.

In this paper, we propose a 60-GHz fractional-N digital frequency synthesizer aimed at reducing its phase noise (PN) at both the flicker (1/f ³ ) and thermal (1/f ² ) regions while minimizing its power consumption. The digitally controlled oscillator (DCO) fundamentally resonates at 20 GHz and co-generates a strong third harmonic at 60 GHz which is extracted to the output while canceling the 20-GHz fundamental. The latter component is fed back to the frequency dividers in an all-digital phase-locked loop for phase detection, which comprises a pair of digital-to-time and time-to-digital converters with dithering to attenuate fractional spurs. The mechanism of flicker noise upconversion to 1/f ³ PN in the DCO is investigated, and a reduction technique is proposed. The 28-nm CMOS prototype achieves 213-277-fs rms jitter in the 57.5-67.2-GHz tuning range while consuming only 40 mW. The DCO flicker PN corner is record low at 300-400 kHz.

The digital-to-time converter (DTC)-based all-digital phase locked loop (ADPLL) attracts more and more attention due to its ultra-lower power consumption characteristic [1]. With DTC, the time-to-digital converter's (TDC) requirements are relaxed, not only for its range but also for its nonlinearity. However, the shortened TDC range, which is less than one digital controlled oscillator (DCO) output period in the new architecture makes the settling time longer and the TDC gain calibration difficult. This work introduces a technique to extend the TDC range by 16 times to accelerate the settling process, while the extended part can be disabled when ADPLL is in lock. Furthermore, the TDC gain calibration is easier.