A mixed-monotonic capacitor switching scheme which can provide stable common-mode voltage (Vcm) without any additional voltage regulator and compensation capacitor array is proposed for the successive approximation register (SAR) analog-to-digital (ADC). The proposed scheme contains two equal amplitude but opposite monotonicity switched capacitor arrays, the stabilization of the common mode voltage is achieved with self-complementation of the differential voltage. Based on this technique, a 10-bit 50 MS/s prototype is designed in CMOS 0.18 μm technology. A window opening SAR logic is used to reduce the transmission time from the comparator out to DAC control signal. An adaptive delay chain is used in the comparator loop to reduce the conversion time of lower bit in the SAR ADC. Measurement result shows that the SAR ADC can achieve a SNDR equal to 57.31 dB, and INL and DNL are equal to 1.81 LSB and 0.98 LSB respectively.
How to apply the Lagrange equation to the continuous medium mechanics has been a theoretical issue of academic circles. Using variational derivative concepts and operational rules, the properties of variational derivative in Lagrange equation are studied. The Lagrange equation is applied to linear elastic dynamics and nonlinear elastic dynamics, and some corresponding numerical examples are given. The result shows that it is a feasible way to solve the problem of the application of Lagrange equation to the mechanics of continuous media by using the variational integral calculus.
This study targets on the practical process of travel survey in Qianmen, Beijing and examines the problems derived from the survey. Their characteristics and the reasons of being generated are stated. The paper focuses on survey organization and its institutional obstacles, the survey design, survey sampling techniques, the choice and training of surveyors and the survey timing. Based on the theoretical researches, the advices towards the innovation of travel survey methods are proposed.