IEEE Transactions on Circuits and Systems

In stability analysis, op-amp circuits are often modeled as single-loop feedback systems, as shown with a finite open-loop gain A in the forward path and β in the feedback path. The author proposes a different model that has two feedback loops. The model is useful in stability of op-amp circuits and in determining the oscillation conditions of Wien-bridge oscillators. The model has o... View full abstract»

An algorithm to obtain possibly absolutely minimal realizations of a given 2-D transfer function is developed. It is algebraic in nature and requires only 1-D realization theory and basic knowledge of linear algebra. Hence, the algorithm is simple and easy to program. The algorithm is guaranteed to yield absolutely minimal realizations for 2-D transfer functions having separable numerators and may... View full abstract»

A class-E high-frequency low-dv/dt synchronous rectifier/DC regulator is analyzed. The circuit is derived from a class-E rectifier by replacing a diode with a controllable switch. It can then both rectify and regulate the rectified output against variations in DC load and amplitude of the AC input voltage. The switch consists of a transistor and an antiparallel diode or a series ... View full abstract»

Use is made of the concept of nonuniform (incommensurate) resonator spacings in order to minimize the linear echo problem. The circuit domain simulation of a general class of parametric coherent echoes, previously modeled by means of uniformly spaced nonlinear resonators, is reexamined. This is accomplished by introducing nonuniform (incommensurate) resonator spacings to represent more closely an ... View full abstract»

The dynamic behavior of neural networks under arbitrary unknown structural perturbations depends essentially on the compatibility/incompatibility of input variables in these networks. Estimates of the upper bounds of the motions of neural networks of either type and exponential stability of compatible neural networks are established by using three different forms of Lyapunov functions. Conditions ... View full abstract»

The authors describe a methodology by which noise sources in converters can be modeled using SPICE. Two converter topologies were used to illustrate the noise analysis methodology. SPICE input files constitute a noise model of a particular converter topology whose noise parameters may be changed to match actual converter noise behavior more closely. SPICE simulations are used to verify the analyti... View full abstract»

The authors propose a technique for designing 2-D digital filters (2DDFs) with specified magnitude and constant group delay characteristics. The method is based on the iterative singular value decomposition (ISVD) of a 2-D magnitude specification matrix. The ISVD guarantees all its decomposition results to be always nonnegative. By using the ISVD, 2-D magnitude specifications can be decomposed int... View full abstract»

A numerical method based on traveling wave theory is presented for the transient analysis of lossy transmission lines with arbitrary terminal networks. The method is well suited to computer programming. By introducing the imaginary transmission line, the network is portioned into two parts. An approach by the S-matrix and the z-transform is applied to the arbitrary terminal netwo... View full abstract»

A substrate-referenced (SR) data-conversion architecture that operates with widely varying single polarity and or bipolar power supplies has been developed. By using well-established analog circuit design techniques and a novel substrate-referenced level-shifting scheme, digital switching noise on the noisiest power supply (V dd in p-well CMOS) appears to the analog subsystem a... View full abstract»

The authors propose a continuous-time current-mode integrator that offers potential advantages for both higher frequency and lower power monolithic filtering applications. Owing to the small voltage swings inherent in current-mode circuits, the integrator time constant is determined by a small-signal transconductance and an additional MOSFET gate capacitance, while good linearity is maintained usi... View full abstract»

A general relationship between the gains of multiterminal amplifiers is derived. This approach generates a constraint for the simultaneous improvement of the common-mode and the power-supply rejection ratio of the simple operational amplifier. This constraint can be relaxed by either adding a supplementary input terminal to the amplifier circuit or using a fully differential design. The method can... View full abstract»

A design methodology for oversampled analog-to-digital converter decimation filters is presented. The methodology tackles the finite-impulse-response (FIR) filter design problem by formulating a quadratic programming problem that minimizes the integral of the aliased noise subject to the passband and stopband constraints. The approach offers a design whose response is optimized to meet arbitrary q... View full abstract»

The authors propose a number of improvements based on the RM8 algorithm aimed at enhancing the visual quality of the reconstructed images, especially at the low rates of 64 and 128 kb/s. RM8 is a novel approach to defining a coding standard for video communications at p ×64 kb/s. Methods studied include reducing the quantizer step size, randomized scanning of the macroblock, and/or ... View full abstract»

The authors develop a design technique for associative memories with learning and forgetting abilities via artificial feedback neural networks. The method utilizes the theory of large-scale interconnected dynamical systems, instead of the usual energy methods. Networks synthesized by this design method are capable of learning new patterns as well as forgetting old patterns without recomputing the ... View full abstract»

The filter-bank structure proposed is based on a digital simulation of a singly terminated ladder filter. This filter bank can also be arrived at from a filter described by G Peceli (1989) and represents an extremely hardware efficient structure, having a complexity of O(N). The main application examined is adaptive line enhancement. The filter-bank-based line enhancer is shown t... View full abstract»

The incorporation of both spatial and spectral adaptivity in a linear restoration algorithm is addressed. The formulation of a combined criterion is proposed, involving the minimum-mean-square-error (MMSE) and the least-mean-square-error (LMSE) criteria, in portions controlled by an indicator of the spatial signal activity. The incorporation of spectral adaptivity is achieved through the use of a ... View full abstract»