Scheduled System Maintenance on May 29th, 2015:
IEEE Xplore will be upgraded between 11:00 AM and 10:00 PM EDT. During this time there may be intermittent impact on performance. We apologize for any inconvenience.
By Topic

Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on

Issue 6 • Date Jun 1995

Filter Results

Displaying Results 1 - 7 of 7
  • A low-power CMOS VGA for 50 Mb/s disk drive read channels

    Publication Year: 1995 , Page(s): 370 - 376
    Cited by:  Papers (82)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    We describe an all CMOS variable gain amplifier (VGA) suitable for use in disk drive read channels. The VGA maintains a 3 dB bandwidth greater than 85 MHz throughout its gain range. This ensures good phase linearity for data transfer rates of up to 50 Mb/s. The VGA provides a 25 db gain variation along an ideal exponential gain to control voltage curve and 30 dB of gain control if ideal exponential characteristics is not absolutely necessary. The VGA achieves the necessary exponential gain to control voltage characteristics intrinsically using only MOS transistors as a single unit to reduce power and area consumption. Overall power consumption is less than 10 mW for the VGA circuit excluding the off-chip buffer circuits View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Partial column FFT pipelines

    Publication Year: 1995 , Page(s): 414 - 423
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    This paper presents the development of two efficient FFT implementation algorithms which allow for more parallelization than the standard pipeline. M=2q radix r parallel computational elements are allocated per column of the FFT flowgraph, and the constant geometry FFT is used for uniform stages. The first method solves the interstage data shuffle problem by decomposing the perfect shuffle matrix into the product of four matrices, with a memory grouping resulting in a reduction of switching from M2 to 2M. The second method decomposes to the perfect shuffle into the product of two matrices, and the memory is partitioned such that multiport elements may be used. All required switching is accomplished via addressing of the multiport elements requiring no external switching elements. Finally implementations are presented which allow for a varied amount of parallization by using uniform modules and merely modifying interconnect wiring View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis and control of the signal dependent performance of adaptive echo cancellers in 4-wire loop telephony

    Publication Year: 1995 , Page(s): 377 - 392
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1176 KB)  

    The central 4-wire loop telephone system, with an adaptive echo canceller at either end of the loop, typically achieves good echo suppression. However, poorly cancelled echoes and/or signal bursting have been observed. Such undesirable behavior has been linked to the presence of cross correlation between and autocorrelation of the signals transmitted by the subscribers. The primary aim of this paper is to quantify the relationship between the correlation levels of the subscriber signals and echo canceller performance in the double echo canceller (DEC) 4-wire loop system. This is achieved by carrying out dynamical analyses of the DEC system. The analyses lead to the determination of conditions on the subscriber signals' correlation levels, satisfaction of which result in guaranteed stable behavior. Furthermore, the analyses indicate that good echo cancellation requires the subscriber signals to have minimal cross correlation and narrow autocorrelation functions. These results lead to the investigation of the whitening and orthogonalizing capabilities of scramblers. A line coding scheme, based on these devices, is identified, which, for essentially all subscriber signals, leads to good echo cancellation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An efficient representation of nonstationary signals using mixed-transforms with applications to speech

    Publication Year: 1995 , Page(s): 393 - 401
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB)  

    A useful technique is presented to efficiently represent nonstationary signals by combining the wavelet and mixed-transforms. First, the signal is split into subbands using the discrete wavelet transform. Specifically, the subband splitting is performed by employing the scaling and the wavelet functions to low-pass and high-pass filter the signal. Next, each of these subbands is represented using superimposed partial sets of basis functions of different transforms, which are in general, mutually nonorthogonal. This is termed the mixed-transforms representation. The residual error, which is the difference between the original subband and the reconstructed subband is properly formulated. Adaptive algorithms are developed to minimize this error and to maximize the Signal to Noise ratio (SNR) of the reconstructed subband for a fixed number of transform components. An optimization strategy is also proposed to select the dominant components from the various domains for adaptation. These efficiently represented subbands are finally combined to reconstruct the signal. Sample results for representing voiced and unvoiced speech signals are given to illustrate the accuracy of the proposed method. A specific class of scaling and wavelet functions are employed in conjunction with the mixed Fourier/Haar transforms. It is verified that for a given number of coefficients, the proposed technique yields a significantly higher SNR of the reconstructed signal than using mixed-transforms alone or the wavelet transform followed by a single transform. Performance comparison is also presented for two different orders of scaling functions belonging to the same family View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stability of the 2-D state-space system with overflow and quantization

    Publication Year: 1995 , Page(s): 432 - 434
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Two-dimensional (2-D) digital filters are investigated with and without the nonlinear effects of overflow and quantization when implemented in fixed-point arithmetic. A sufficient condition is established for the stability of the linear Fornasini-Marchesini state-space model. The same system is then studied for stability when implemented using two's complement arithmetic. The combined effects of overflow and quantization are considered, and sufficient conditions for stability are derived View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonorthogonal signal representation by Gaussians and Gabor functions

    Publication Year: 1995 , Page(s): 402 - 413
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    This paper describes a novel approach for nonorthogonal representation of signals using Gaussians and an extension of this method for Gabor representation of signals, based on the equivalence of Gabor expansion to Gaussian expansion in the frequency domain. The Gaussian expansion scheme yields an efficient representation of signals for low number of bits per pixel and is better than the corresponding Discrete Cosine Transform (DCT) representation for very low bit rates. This advantage diminishes gracefully for higher bit rates where the residual approximation error signal to be represented is more random and less structured. It is proved in this paper that a finite number of Gaussians can theoretically approximate sinusoids in a bounded region with arbitrarily small error, and therefore any finite support L2 (R) signal as well. Two methods for Gaussian representation of signals are outlined. The first, called the Max-Energy paradigm, involves successive extraction of the highest energy Gaussian that best “fits” the signal. The second is a parallel approach and uses an adaptive projection algorithm to first derive the Gaussian basis set to be used in parallel, and then optimizes the coefficients for minimum squared error View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design of multidimensional finite-wordlength FIR and IIR filters by simulated annealing

    Publication Year: 1995 , Page(s): 424 - 431
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (780 KB)  

    This paper describes a new approach to the design of multidimensional (M-D) finite-wordlength digital filters with specifications in the frequency and spatial domains. The approach is based on stochastic optimization and extends previous work on finite impulse response (FIR) filters in two ways: by inclusion of spatial constraints and by application to the case of infinite impulse response (IIR) filters. The formulation proposed is based on a multiple-term objective function that, in addition to magnitude constraints, also includes step response, group delay and stability constraints. Our attention to these characteristics stems from the application of such filters to video processing that we are actively pursuing. Since filter coefficients are of finite precision and since the objective function is multivariable, nondifferentiable and likely to have multiple minima, we use simulated annealing for optimization. We show numerous examples of the design of practical filters such as channel and luminance/chrominance separation filters used in the NTSC system. We demonstrate the impact of coefficient precision as well as of group delay and step response constraints on filter parameters View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

This title ceased production in 2003. The current updated title is IEEE Transactions on Circuits and Systems II: Express Briefs.

Full Aims & Scope