Wuhuang Huang

Timing Skew Calibration Method for TIADC-Based 20 GSPS Digital Storage Oscilloscope

Time-interleaved technique is widely used to increase the sampling rate of analog-to-digital converter (ADC). However, the channel mismatches degrade the performance of time-interleaved ADC (TIADC). When input signal frequency is very high, timing skews have significant effect on distortion. Therefore, a new timing skew calibration method is proposed in this paper. This method is based on the truth that timing skews are related to the product of the outputs of sub-ADCs. After timing skews are estimated, the digital controlled delay elements (DCDE) in ADC and phase locked loop (PLL) are utilized to calibrate timing skews. No auxiliary circuit and digital filter are needed for this calibration method. Simulation results show that the proposed method can estimate timing skew accurately. It is also proved that an accurate estimation can be obtained even the signal to noise ratio (SNR) of input signal is 20dB. The proposed method is employed to calibrate timing skews in a 16-channel TIADC-based 20GSPS digital storage oscilloscope (DSO). The experiment results demonstrate the usefulness of the proposed method. We can see that after timing skews are calibrated, the spectrum spurs have been effectively eliminated.

Analysis on multiple-component synchronization of ultra-fast time-interleaved analog-to-digital conversion systems and its novel parameterized hardware solution.

Parallelism-based technique of time-interleaved analog-to-digital conversion (TIADC) has become an effective solution for the higher sampling rate acquisition system to acquire non-repetitive waveforms. With the increase of sampling frequency, the indeterminacy of combining sequence of sampled data among multiple components has become a highlighted barrier for the reset operation of high-speed acquisition systems, and this is especially obvious for the ultra-fast TIADC systems. In this paper, we clarify the root of the problem in multiple-component synchronization (MCS) caused by such reset operation. Also we propose a novel and reliable hardware solution to precisely condition each reset signal, including three key circuit design parameters, i.e., the best time interval, required edge uncertainty, and the minimum delay precision. Besides, the designing scheme and debugging procedures are presented in detail in a generalized platform of this system type. Finally, in order to demonstrate the feasibility, parametric materialization and testing verification are gradually accomplished in a 20 Giga Samples Per Second (GSPS) TIADC system composed of four 5 GSPS ADC components. The results show that the proposed method is feasible and effective for ensuring the combined determinacy of multiple groups of sampled data and solving the MCS problem. In comparison with other existing solutions, it adopts some simple logic components more easily and flexibly, and this is significant for the development of congeneric systems or instruments featuring the MCS.

A new method for measuring properties of liquid by using a single quartz crystal microbalance

As an ultra-sensitive mass sensing device, quartz crystal microbalance (QCM) can also be used to detect a variety of analytes in liquid environment. Previous works reported separate density and viscosity measurements of liquid by using dual QCMs. In this work, we present a novel theoretical model and a new method to separate density and viscosity measurements of liquid only using a single QCM, based on the frequency response analysis. Experimental results demonstrate the merit of the single QCM setup in determining the physical properties of liquid is an exciting new solvent.

Seamless measurement technology of transient signals based on approximate entropy

The acquisition of waveforms and the analysis of transient characteristics of signals are the fundamental tasks for time-domain measurement, while the reduction of the measuring gap till seamless measurement is extremely important to the acquisition, measurement, and analysis of transient signals. This paper, aimed at the seamless time-domain measurement of non-stationary transient signals, proposes an approximate entropy-based characteristic signal extraction algorithm on the basis of information entropy theories. The algorithm quantitatively describes the complexity (amount of information) of sampled signals using the approximate entropy value, self-adaptively captures characteristic signals under the control of the approximate entropy in real time, extracts the critical or useful information, and removes redundant or useless information so as to reduce the time consumption of processing data and displaying waveforms and realize the seamless time-domain measurement of transient signals finally. Experimental results show that the study could provide a new method for the design of electronic measuring instrument with seamless measurement capability.