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Synchronous demodulation based on time shifted subtraction. The V p, V n samples are identified according to the value of SC′ signal.
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Low frequency 1/f noise is one of the key limiting factors of high precision measurement instruments. In this paper, digital correlated double sampling is implemented to reduce the offset and low frequency 1/f noise of a data acquisition system with 24-bit sigma delta (Σ-Δ) analog to digital converter (ADC). The input voltage is modulated by cross-...
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... subtraction. It is based on the fact that the low frequency noise is self-correlated. By shifting the original signal SM by half a period, which is 16 samples, we can divide the original sample series into two complete series, positive phase samples V p , which express V in , and negative phase samples V n , which express −V in , as shown in Fig. 6. The two complete sample series V p and V n can be expressed ...Similar publications
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Citations
... This fact is either due to special features like built-in auto-zeroing or chopping stages, or is a merit of the circuit realization. Techniques like correlated double sampling (CDS) can be employed to effectively suppress 1/f noise [26], at the expense of extra circuitry and added latency [27]. ...
... The dominance of the Sigma-Delta architecture is evident, although a number of SAR ADCs are catching up. Customized and hybrid digitizers [5] [27] are still capable of achieving higher dynamic range than fully integrated solutions. ...
Analog-to-digital converters with resolution exceeding 20 bits are widely available today. They exist in two forms-flexible laboratory instruments and monolithic integrated circuits. We present an overview of application fields for such digitizers, the hardware architectures that implement them, and their limitations. We review the state of the art by comparing the best-performing devices reported in scientific literature, as well as those available commercially. Our focus is particularly on integrated circuit solutions, and among our aims are the disambiguation of the multiple performance metrics in use, as well as the presentation of a clear perspective on basic performance trade-offs. Finally, we provide a discussion on the future prospects for high-resolution digitizing measurement systems.
The metal magnetic memory (MMM) non-destructive testing method is widely accepted for its strong environmental adaptability, high sensitivity, and simple measurement operation. Nevertheless, due to the complex environmental factors, and the influence of detection distance, it is still a technical challenge to perform high-accuracy pipeline inspection at high lift-off values, where the lift-off value is the distance between the magnetic probe and the surface of the pipe. To better study the MMM field model, this paper puts forward the high lift-off distance MMM - three dimensional (HDMMM-3D) differential method of
G<sub>z</sub>
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The dynamic range of the currently most widely used 24-bit seismic data acquisition devices is 10–20 dB lower than that of broadband seismometers, and this can affect the completeness of seismic waveform recordings under certain conditions. However, this problem is not easy to solve because of the lack of analog to digital converter (ADC) chips with more than 24 bits in the market. In this paper, we propose a method in which an adder, an integrator, a digital to analog converter chip, a field-programmable gate array, and an existing low-resolution ADC chip are used to build a third-order 16-bit oversampling delta-sigma modulator. This modulator is equipped with a digital decimation filter, thus facilitating higher resolution and larger dynamic range seismic data acquisition. Experimental results show that, within the 0.1–40 Hz frequency range, the circuit board’s dynamic range reaches 158.2 dB, its resolution reaches 25.99 bits, and its linearity error is below 2.5 ppm, which is better than what is achieved by the commercial 24-bit ADC chips ADS1281 and CS5371. This demonstrates that the proposed method may alleviate or even completely resolve the amplitude-limitation problem that so commonly occurs with broadband observation instruments during strong earthquakes.
