Low Jitter Time Research Articles

A 346 µm 2 VCO-Based, Reference-Free, Self-Timed Sensor Interface for Cubic-Millimeter Sensor Nodes in 28 nm CMOS

We present a 346 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> reference-free, asynchronous VCO-based sensor interface circuit demonstrated in 28 nm LP bulk CMOS. This design is specifically for sensor node interfaces which do not have the power or volume available for the high accuracy current sources, voltage sources, or low jitter timing references needed for traditional ADCs. By using a straightforward VCO design, it achieves wide resolution, voltage scalability, and process portability while consuming only ~1/100th the area of prior approaches and avoiding costly reference circuitry. In the design measured for this paper, resolution can be scaled from 2.8 to 11.7 bits and VDD from 500 mV to 1.0 V. The design contains a single-point calibration scheme that works across temperature, voltage, and resolution settings. Minimum power consumption is 11.7 μW at 0.6 V VDD and minimum energy per conversion step is 41.2 fJ/b at 0.6 V VDD and 9.42 bits of effective resolution.

High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits

Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18 ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics.

A CMOS 1&amp;lt;tex&amp;gt;$times$&amp;lt;/tex&amp;gt;–16&amp;lt;tex&amp;gt;$times$&amp;lt;/tex&amp;gt;Speed DVD Write Channel IC

Optical recording demands a meticulous write strategy to control the laser beam power and regulate the phase change layer temperature tightly. The width, height, and delay of a string of short pulses applied to the laser diode need to be adjusted in fine steps, and the writing speed varies widely per applications. A multi-phase phase-locked loop (PLL) tracks a wide range of clock frequencies, and provides a low-jitter time base for write pulses. With two enabling circuit concepts, PLL loop filter voltage folding/unfolding and switch-in of parallel MOS resistors in delay cells, it is possible to operate a PLL to cover a frequency range spanning over three octaves with one VCO. A 10-stage differential VCO is phase-locked to the input channel clock ranging from 26 to 420 MHz (1/spl times/-16/spl times/ DVD speed), and its 20-phase outputs are used to generate write pulses. The pulsewidth and delay are programmed with 120 /spl plusmn/ 40 ps time resolution. The prototype chip fabricated in 0.35 /spl mu/m CMOS occupies 3.5/spl times/3.3 mm/sup 2/, and consumes 294 mW at 3.3 V.

Data sequence coding for low jitter timing recovery

The letter considers the timing content of a random data sequence and presents a line coding technique to achieve reliable, low-jitter timing recovery.

KrF Laser-Triggered SF6 Spark Gap for Low Jitter Timing

KrF laser-triggered spark gaps exploit the high dc-dielectric strength and low ultraviolet (UV) breakdown threshold of SF6 gas. Detailed measurements using a dc-charged pulser demonstrate subnanosecond jitter for switching a 0.5-cm gap operated at 80 kV with 7 mJ in 20 ns of 248-nm KrF radiation. A 200-kV pulse-charged 0.7-cm gap gives similar performance.