一种CMOS动态闩锁电压比较器的优化设计

提出了一种应用于Pipeline ADC和Sigma-Delta ADC中改进的动态闩锁电压比较器。采用0.35μm CMOS N阱工艺设计,工作于2.5V单电源电压。通过详细的分析和优化,使比较器具有较小的输入失调电压和踢回噪声,仿真结果表明它的输入失调电压分布范围为28.6mV,最高工作频率200MHz、功耗230μW。     

A novel low-power,low-offset,and high-speed CMOS dynamic latched comparator

A novel dynamic latched comparator with offset voltage compensation is presented. The proposed comparator uses one phase clock signal for its operation and can drive a larger capacitive load with complementary version of the regenerative output latch stage. As it provides a larger voltage gain up to 22 V/V to the regenerative latch, the input-referred offset voltage of the latch is reduced and metastability is improved. The proposed comparator is designed using 90 nm PTM technology and 1 V power supply voltage. It demonstrates up to 24.6% less offset voltage and 30.0% less sensitivity of delay to decreasing input voltage difference (17 ps/decade) than the conventional double-tail latched comparator at approximately the same area and power consumption. In addition, with a digitally controlled capacitive offset calibration technique, the offset voltage of the proposed comparator is further reduced from 6.03 to 1.10 mV at 1-sigma at the operating clock frequency of 3 GHz, and it consumes 54 μW/GHz after calibration.     

Input voltage sensitivity of GaAs/GaAlAs HEMT latched comparator

The input voltage sensitivity represents a critical parameter for a latched comparator in high-speed and high-precision data conversion applications. An analytical prediction of this parameter is presented and has been verified to be in good agreement with the experimental results from a high performance latched comparator implemented in 0.5 mu m GaAs/GaAlAs E/D HEMT technology.<>     

A high-speed latched comparator with low offset voltage and low dissipation

An ultra high-speed latched comparator using a controlled amount of positive feedback cell has been designed in TSMC 0.18 μm CMOS technique. Transmission gate (TG) switches are used to implement the preamplifier circuit. The use of TG switches results in a reduction in the power consumption of the high-speed comparator as well as clock feedthrough and the effect of charge injection. The simulation results demonstrate that it can work at 1.25 GHz suitable for high speed applications, and consumes 273.6 μW with a power supply of 1.8 V at 100 MHz and Monte Carlo simulation shows that the comparator has a low offset voltage approximately 0.499 mV.     

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。     

一种基于半闪速结构的动态比较器

模数转换器的核心是比较器,本文讨论了比较器的性能和动态比较器的工作原理、引起电荷注入、时钟馈通的原因以及如何消除,然后通过仿真图观察动态比较器的工作状态、传输时延及精度等特性。     

Natoinal bureau of standards noise comparator

This paper is concerned with the measurements of the power spectrum of fluorescent tubes in the frequency range between 6-10 kmc. It has two main purposes: to discuss the experimental set-up used for calibrating fluorescent tubes to be used as secondary noise standards; and to study experimentally the law of available noise power of a discharge tube.     

Phase noise cancellation in a carrier recovered optical heterodynereceiver

The performance and application of an optical heterodyne receiver which uses a carrier recovery demodulator are described. Phase sensitive demodulators used in coherent optical transmission are compared, and the suppression of both phase noise and frequency instability of light sources by a carrier recovery (CR-) demodulator is described. A carrier recovered PSK (CR-PSK) demodulator and a phase noise canceling circuit (PNC) for a coherent SCM receiver are introduced as examples of CR-demodulators. The relationship between laser diode spectral linewidths and the delay time difference between the two paths in the CR-PSK demodulator necessary to keep the system performance within a certain power penalty is then derived. In a preliminary experiment using 560-Mb/s CR-PSK transmission, a receiver sensitivity of -51.6 dBm was obtained, and a laser phase noise suppression of about ¹/₂ that of DPSK was confirmed. The results suggest the possibility of constructing a heterodyne receiver which has no AFC-loop. Applications of a CR-demodulator to an optical frequency division multiplexing (OFDM) system and to a multivalue modulation scheme are discussed     

Impulsive noise cancellation in multicarrier transmission

A parallel between Reed-Solomon codes in the complex field and multicarrier transmission using orthogonal frequency-division multiplexing (OFDM) is first presented. This shows that when the signal is sent over some channel composed of Gaussian plus impulsive noise, the impulsive noise can be removed by a procedure similar to channel decoding, using information carried by the "syndrome." This result is first derived in a simple situation (oversampled discrete multitone, additive channel), which is merely of theoretical interest. In any case, consecutive zeros, in the output of the OFDM modulator, do not correspond to real subcarriers. Pilot tones are transmitted for synchronization or channel-estimation purposes. These pilot tones are generally scattered among the information ones. Our approach is to use these pilot tones as syndromes, in order to correct impulsive noise. We show that the correction capacity is conditioned by the position of these pilot tones in the transmitted sequence. A protection subsystem based on hypotheses tests is introduced after the decoding operation in order to detect malfunctions of this decoder. The efficiency of this technique is corroborated with simulations in the slightly modified Hiperlan2 context. Other extensions are then provided in order to increase the practical usefulness of the method.     

Optimization of a cascaded structure for noise and echo cancellation using a noise filtering preprocessing

This paper deals with speech enhancement in hands-free telecommunication systems. The two major problems encountered in such contexts - noise reduction and acoustic echo cancellation - are addressed. After the presentation of the two basic cascaded structures found in the literature, we propose a new promising technique which takes advantage of the previous ones. The main objective is to get a near-end speech signal with low levels of distortion, echo and noise. The structure is tested in a real mobile environment and compared with the two others. An objective evaluation shows the improvement provided by this structure.     

Adaptive noise cancellation with a SAW storage correlator

A Sezawa wave storage correlator was used to implement an adaptive filter for noise cancellation. The filter reduced the level of a 150 MHz CW jamming signal by 26 dB and a broadband Sezawa wave convolver was used to compress an underlying chirp signal. The tap weights are determined in 40 to 100 ?s, depending on the jamming signal power and feedback gain.     

Active cancellation of acoustic noise using a self-tuned filter

In an increasingly noisy society, methods of reducing noise are becoming more important. This work proposes an analog electroacoustic circuit for active control of narrow-band low-frequency acoustic noise using adaptive filtering techniques. The circuit aims at producing antinoise, which is acoustically added to the disturbing noise to produce an error signal that is fed back to the circuit. The proposed circuit is a modified Kerwin-Huelsman-Newcomb biquad filter that tunes itself to the incoming noise frequency using the zero tuning techniques. The circuit was implemented on a printed circuit board and it was successful in reducing noise by 15-20 dB in open space. Active noise control specifically for narrow-band noise cancellation using adaptive analog filters seems to be a better solution than its digital signal processing counterpart in speed, cost, and robustness.     

ELMS算法在噪声抵消中的应用

介绍一种改进的算法在噪声消除中的应用.算法利用第二级滤波器估计期望信号,然后在第一级滤波器中消除期望信号对算法误差的影响.仿真表明算法可以明显地降低算法的均方误差,得到很好的输出性能.     

Mismatch sensitivity of a simultaneously latched CMOS senseamplifier

Derives a new formula for the sensitivity of a vertically matched CMOS sense amplifier, of the type used in dynamic-RAMs (DRAMs), to threshold voltage mismatch, parasitic capacitance mismatch, transconductance mismatch, and bit-line load capacitance mismatch. The formula yields insight into the DRAM sensing operation. The authors derive a sensitivity formula for this sensing scheme, using perturbation theory. The perturbation approach is rigorous: it avoids most approximations and ad-hoc assumptions, it introduces no free constants to be determined from simulations, and it yields an explicit closed-form solution. The formula agrees well with simulations. It is inherently slightly conservative and thus appropriate for use in design     

噪声对消射频光子链路的噪声系数研究

噪声系数是宽带射频光子链路的重要参数,影响射频信号传输和处理系统的信噪比.提出了一种噪声对消射频光子链路,采用平衡光探测器对直流光和调制光转换的光电流相减处理,得到链路的噪声系数改善.从光信号调制、探测及噪声功率变化特性出发,建立了噪声对消射频光子链路的理论模型,并通过理论分析研究了噪声系数与激光功率、相对强度噪声、光...     

Passive cancellation of common-mode noise in power electronic circuits

It is well known that common-mode (CM) conducted electromagnetic interference (EMI) is caused by the common-mode current flowing through the parasitic capacitance of transistors, diodes, and transformers to ground in the power circuit. Because of the potential for interference with other systems it is necessary to attenuate this noise. Ordinarily this is accomplished by using a magnetic choke across the input power lines, resulting in penalties to the overall size and cost of the completed system. In order to lessen the requirement for this magnetic choke, there has been a desire to introduce noise cancellation techniques to the area of EMI. This text introduces a method of canceling the common-mode EMI by using a compensating transformer winding and a capacitor. Compared with other cancellation techniques, it is much simpler and requires no additional transistors and gate-drive circuitry since it merely adds a small copper winding and a small capacitor. By using this technique the size of the EMI filter can be reduced, especially for applications requiring high currents. In this paper, the new method for passive noise cancellation is applied to many popular converter and inverter topologies. The method, results, and ramifications of this technique are presented in order of appearance.     

Active cancellation system of acoustic noise in MR imaging

Introduces a new neural-network architecture for reducing the acoustic noise level in magnetic resonance (MR) imaging processes. The proposed neural network (NN) consists of two cascaded time-delay NNs (TDNNs). This NN is used as the predictor of a feedback active noise control (ANC) system for reducing acoustic noises. Experimental results with real MR noises show that the proposed system achieved an average noise power attenuation of 18.75 dB, which compares favorably with previous studies. Preliminary results also show that with the proposed ANC system installed, acoustic MR noises are greatly attenuated while verbal communication during MRI sessions Is not affected     

Clipping noise cancellation in OFDM systems using oversampledsignal reconstruction

Clipping the OFDM signals in the digital part of the transmitter is one of the simplest methods to reduce the peak factor. However, it suffers from additional clipping distortion, peak regrowth after digital to analog conversion, and out-of-band radiation in the case of oversampled sequence clipping. We use oversampled sequence clipping to combat the effect of peak regrowth and propose a method to reconstruct the clipped samples and mitigate the clipping distortion in the presence of channel noise at the expense of bandwidth expansion. We show through extensive simulations that by slightly increasing the bandwidth of the system, we can significantly improve the performance while limiting the maximum amplitude of the analog signal