Noise-cancelling switched-capacitor (SC) filtering technique

A method of reducing the 1/f noise in SC filters is shown using an initialising technique. This technique also removes the input offset of the operational amplifier, and thus gives an offset-free SC building block. Experimental results for a first-order lowpass filter illustrating the above are presented.     

A low-noise chopper-stabilized differential switched-capacitor filtering technique

Describes the implementation of a wide dynamic range voiceband switched-capacitor filter using a differential chopper-stabilized configuration. The noise behavior of switched-capacitor filters is discussed qualitatively, and the effects of the chopper stabilization on the noise performance is analyzed. Experimental results from a fifth-order low-pass voiceband prototype are presented.     

Technological design considerations for monolithic MOS switched-capacitor filtering systems

In this paper, various technological and topological considerations for the design of monolithic MOS switched-capacitor (SC) filtering systems are described. The properties of the passive and active devices typically available in depletion-load NMOS and CMOS technologies are presented as they relate to various SC peformance parameters. Layout techniques for improving specific performance parameters are also given. An overview of MOS operational-amplifier design emphasizes technological considerations in the design of high-performance SC systems. Finally, several important techniques are reviewed for maximizing dynamic range in SC circuits.     

Integrated MOS four-quadrant analogue multiplier using switched-capacitor technique

A fully integrated four-quadrant analogue multiplier based on switched-capacitor technique for realisation of high-speed and high-density analogue LSIs was developed using a MOS VLSI process. Excellent characteristics such as low total harmonic distortion of ?50 dB for two input signals of 1 Vp-p, large dynamic range of 80 dB and fast operation speed of 2 MHz clock rate were obtained. Application to convolvers and correlators is also demonstrated.     

Floating integrator technique for switched-capacitor circuits employing reset cycles

A simple `floating? integrator technique is presented that is applicable to both single-ended and differential switched-capacitor circuits which employ reset cycles. This method is useful in eliminating the effects of any input offset or interstage differential or common-mode offsets in DC-coupled circuits. A monolithic circuit is demonstrated which uses this technique to achieve accurate differential integration of low-level signals in the presence of substantial differential and common-mode input offsets.     

Frequency shift filtering technique

A heterodyne continuous time active filter is described. Control over the operating has been achieved without external components, through a tunable local oscillator. It has been possible to build a single chip filter that may be tuned from very low frequencies up to 70 kHz in a single range     

一种用于SAR ADC开关电容比较器的失调消除技术

论文阐述了一种用于逐次逼近ADC开关电容比较器的失调消除技术。采用预放大加再生锁存的比较结构,基于0.18μm 1P5M CMOS工艺设计实现了一种伪差分比较器。通过采用前级预放大器输入失调消除技术以及低失调再生锁存技术进行设计,整个比较器的输入失调电压小于0.55mV。通过采用预放大加再生锁存的比较模式,整个比较器的功耗有效减小,不足0.09mW。在电源电压为1.8V、ADC采样速率为200kS/s、时钟频率为3MHz的情况下,比较器能达到13位的转换精度。最后,通过设计讨论、后仿真分析及其在一种10位200kS/s的触摸屏SAR ADC中的成功应用验证了本文比较器的实用性和优越性。     

BEACON: an adaptive set-membership filtering technique with sparseupdates

This paper deals with adaptive solutions to the so-called set-membership filtering (SMF) problem. The SMF methodology involves designing filters by imposing a deterministic constraint on the output error sequence. A set-membership decision feedback equalizer (SM-DFE) for equalization of a communications channel is derived, and connections with the minimum mean square error (MMSE) DFE are established. Further, an adaptive solution to the general SMF problem via a novel optimal bounding ellipsoid (OBE) algorithm called BEACON is presented. This algorithm features sparse updating, wherein it uses about 5-10% of the data to update the parameter estimates without any loss in mean-squared error performance, in comparison with the conventional recursive least-squares (RLS) algorithm. It is shown that the BEACON algorithm can also be derived as a solution to a certain constrained least-squares problem. Simulation results are presented for various adaptive signal processing examples, including estimation of a real communication channel. Further, it is shown that the algorithm can accurately track fast time variations in a nonstationary environment. This improvement is a result of incorporating an explicit test to check if an update is needed at every time instant as well as an optimal data-dependent assignment to the updating weights whenever an update is required     

Multichannel fast QRD-LS adaptive filtering: new technique andalgorithms

A direct, unified approach for deriving fast multichannel QR decomposition (QRD) least squares (LS) adaptive algorithms is introduced. The starting point of the new methodology is the efficient update of the Cholesky factor of the input data correlation matrix. Using the new technique, two novel fast multichannel algorithms are developed. Both algorithms comprise scalar operations only and are based exclusively oh numerically robust orthogonal Givens rotations. The first algorithm assumes channels of equal orders and processes them all simultaneously. It is highly modular and provides enhanced pipelinability, with no increase in computational complexity, when compared with other algorithms of the same category. The second multichannel algorithm deals with the general case of channels with different number of delay elements and processes each channel separately. A modification of the algorithm leads to a scheme that can be implemented on a very regular systolic architecture. Moreover, both schemes offer substantially reduced computational complexity compared not only with the first algorithm but also with previously derived multichannel fast QRD schemes. Experimental results in two specific application setups as well as simulations in a finite precision environment are also included     

Harmonic analysis via Kalman filtering technique

A recursive computer method for harmonic analysis of a noisy periodic signal is presented. It is shown that with a suitable model for harmonic coefficients, a simple application of Kalman filtering technique can yield minimum variance estimates of the coefficients. The proposed method is illustrated with the help of simulation results.     

An adaptive filtering technique for pilot-aided transmissionsystems

One of the main design tradeoffs of pilot-based techniques of combating the effects of multipath fading is the pilot filter bandwidth. The approach presented is to store a precalculated bank of pilot filters and automatically select the best one as the signal-to-noise, (SNR) or vehicle speed change. The authors address the issue of adjusting the filter bandwidth as speed changes. They call this technique the filter switching algorithm. This technique can provide a 1.0 dB improvement for a normalized Doppler frequency of 2%; up to 2.0 dB can be gained when operating at a lower Doppler frequency. The algorithm is found to be very robust, in the sense that self-noise and decision direction have little effect on its operation and the resulting bit error rate     

Chaos from switched-capacitor circuits: Discrete maps

A special-purpose analog computer made of switched-capacitor circuits is presented for analyzing chaos and bifurcation phenomena in nonlinear discrete dynamical systems modeled by discrete maps xn + 1= f(xn) Experimental results are given for four switched-capacitor circuits described by well-known discrete maps; namely, the logistic map, the piecewise-linear unimodal (one-hump) map, the Hénon map, and the Lozi map.     

数字图像中值滤波技术研究

中值滤波作为图像处理中的一种非线性滤波技术,在有效抑制脉冲噪声的同时能很好地保护图像信号的细节信息,尤其是在处理椒盐噪声方面效果较好,得到了广泛的研究和应用。文章通过对中值滤波及其改进方法的研究,比较了不同方法的运算效率及对不同图像的去噪效果,分析中值滤波技术的研究方向。     

A differential narrow-band switched capacitor filtering technique

A new resonator loss cancellation technique is described using NMOS technology. It allows the implementation of high Q switched capacitor band-pass filters using single-stage low-gain amplifiers. The approach exchanges the amplifier high DC-gain requirement by a gain matching between amplifiers of the same resonator. A prototype sixth-order bandpass filter with center frequency of 100 kHz and a 5 kHz bandwidth was built to demonstrate the feasibility of the technique. Unloaded resonator quality factors of the order of 400 were achieved using amplifiers with a DC gain of 50.     

A Fast FIR filtering technique for multirate filters

This paper presents a technique for applying Fast FIR Algorithms (FFAs) to interpolation and decimation filters. In the event that the prototype filter has a symmetric impulse response, it is shown that the subfilters which result from the application of the FFA will be jointly symmetric. This fact may be exploited in order to further reduce the computational complexity of the system. The effect of transposition upon the proposed structure is discussed, and it is shown that transposition yields a more economical structure in the case of a decimation filter. The computational complexity of the proposed schemes is shown to compare favorably with that of the standard parallel filtering approach.