A field-programmable-gate-array based high time resolution arbitrary timing generator with a time folding method utilizing multiple carry-chains.

A carry-chain based high time resolution arbitrary timing generator, which is fully implemented using field-programmable-gate-array resources, is reported in this paper. The arbitrary timing generator channel operates with two alternative carry-chains to achieve non-dead-time timing sequence generation, and a 45.3 ps time resolution with a 383 ps minimum pulse width can be obtained. The time resolution is further improved to 11.3 ps by employing four parallel carry-chains in a single arbitrary timing generator channel to realize "time folding." The timing generator has a high time stability, and the time uncertainty is below 12 ps within a wide time range of 1 ns-108 ns. The arbitrary timing generator can be used to generate continuous spike timing sequences with a picosecond time resolution.

A high resolution time-to-digital-convertor based on a carry-chain and DSP48E1 adders in a 28-nm field-programmable-gate-array.

A field-programmable-gate-array (FPGA) based time-to-digital-converter (TDC), which combines different types of delay chains in a single time measurement channel, is reported in this paper. A new TDC architecture is developed, and both a carry-chain and the DSP48E1 adders, which are integrated inside the FPGA chip, are employed to achieve high resolution time tagging. A single channel TDC has a 3.3 ps averaged bin size, a 5.4 ps single-shot precision, and a maximum sampling rate of 250 MSa/s. The differential-non-linearity of the single TDC channel is -3.3 ps/+24.1 ps, and the integral-non-linearity is within -10.4 ps/+68.6 ps. The TDC performance can be improved by using four TDC channels to measure one input signal, and a 3.4 ps single-shot precision can be obtained. Due to the implementation of the delicated TDC structure, only a small amount of digital resources is required to achieve the picosecond time measurement resolution. Therefore, the reported TDC architecture is suitable for multi-channel applications that require high time resolution measurements of multiple input signals.

A fully-adjustable picosecond resolution arbitrary timing generator based on multi-stage time interpolation.

We report a fully adjustable arbitrary timing generator (ATG) that is based on a multistage time interpolation method. A 3 ps timing adjustment resolution is achieved using a three-stage time interpolation module. The output signal amplitude of the ATG is adjustable, as a current controlled output module is designed to adjust the output voltage of driver circuits. A field programmable gate array is used to realize the main logic of the ATG. A 3.2 ps short term jitter, a pulse width dynamic range from 6.25 ns to 5 s, and an output voltage range between -1 and +5 V are obtained. The arbitrary timing generator can be used in the applications that require high precision timing control and adjustable output capacity.

A pico-second resolution arbitrary timing generator based on time folding and time interpolating.

We report a pico-second resolution arbitrary timing generator which is implemented with a field-programmable-gate-array. The arbitrary timing/pattern generator is based on a time folding method which is combined with a delay chain for fine time interpolating. The time folding method can not only break the limitation of sequence time resolution contributed by the minimum chain cell delay but also improve the chain linearity. The arbitrary timing generator which is based on the time folding technique is integrated in a printed-circuit board, and a 5 ps time resolution with enhanced output linearity is obtained. The dynamic range of output pulses from the arbitrary timing generator is from 5 ns to 10 s. In this paper, we describe the principle, the circuit design, and the characterizations of the arbitrary timing generator. We also discuss the improvement of performance in timing generation using the time folding method. The high-performance arbitrary timing generator has a bright future to be used in the applications that require high-resolution timing sequence generation.

[Effects of Heat and Heat-alkaline Treatments on Disintegration and Dissolved Organic Matter in Sludge].

The hydrolysis of sludge organic matter is the rate-limiting step of anaerobic sludge digestion. Because pretreatments can effectively convert the solid organic matter into dissolved organic matter, it can improve the degradation rate and methane conversion rate of organic matter. In this study, the effects of heat and heat-alkaline treatments (two common pretreatments) on the composition, relative molecular weight distribution, and structure of dissolved organic matter in sludge were studied. The results showed that the heat and heat-alkaline treatments released a large amount of organic matter, which resulted in the SCOD increasing 21.9 times (heat treatment) and 47.8 times (heat-alkaline treatment). These pretreatments changed the molecular weight distribution of dissolved organic matter and decreased the molecular weight of the organic matter to the greatest degree. The results of three-dimensional fluorescence spectroscopy showed that both of the pretreatments can hydrolyze protein, the main component of sludge soluble organic matter, with the heat-alkaline treatment being more significant. In dissolved organic matter, the byproducts of the microorganisms and humic acids are not easily hydrolyzed further by the two pretreatments. In addition, the two pretreatments led to the appearance of new organic structures and the change and even disappearance of the original organic matter.