A SHA-less 14-bit, 100-MS/s pipelined ADC with comparator offset cancellation in background

A 14-bit 100-MS/s pipelined analog-to-digital converter（ADC） without dedicated front-end sampleand-hold amplifier（SHA） is presented. In addition to elaborate matching of the sampling network in the first stage,a background offset cancellation circuit is proposed in this paper to suppress the offset of the comparators in the first-stage sub-ADC, which ensures the overall offset does not exceed the correction range of the built-in redundant structure. Fabricated in a 0.18- m CMOS technology, the presented ADC occupies a chip area of 12 mm2, and consumes 237 mW from a 1.8-V power supply. Measurement results with a 30.1-MHz input sine wave under a sampling rate of 100 MS/s show that the ADC achieves a 71-d B signal-to-noise and distortion ratio（SNDR）,an 85.4-d B spurious-free dynamic range（SFDR）, a maximum differential nonlinearity（DNL） of 0.22 LSB and a maximum integral nonlinearity（INL） of 1.4 LSB.

Similarities and differences of city-size distributions in three main urban agglomerations of China from 1992 to 2015： A comparative study based on nighttime light data

Comparing the city-size distribution at the urban agglomeration（UA） scale is important for understanding the processes of urban development. However, comparative studies of city-size distribution among China＇s three largest UAs, the Beijing-Tianjin-Hebei agglomeration（BTHA）, the Yangtze River Delta agglomeration（YRDA）, and the Pearl River Delta agglomeration（PRDA）, remain inadequate due to the limitation of data availability. Therefore, using urban data derived from time-series nighttime light data, the common characteristics and distinctive features of city-size distribution among the three UAs from 1992 to 2015 were compared by the Pareto regression and the rank clock method. We identified two common features. First, the city-size distribution became more even. The Pareto exponents increased by 0.17, 0.12, and 0.01 in the YRDA, BTHA, and PRDA, respectively. Second, the average ranks of small cities ascended, being 0.55, 0.08 and 0.04 in the three UAs, respectively. However, the average ranks of large and medium cities in the three UAs experienced different trajectories, which are closely related to the similarities and differences in the driving forces for the development of UAs. Place-based measures are encouraged to promote a coordinated development among cities of differing sizes in the three UAs.