Operational transconductance amplifier-based nonlinear function syntheses

It is shown that the operational transconductance amplifier, as the active element in basic building blocks, can be efficiently used for programmable nonlinear continuous-time function synthesis. Two efficient nonlinear function synthesis approaches are presented. The first approach is a rational approximation, and the second is a piecewise-linear approach. Test circuits have been fabricated using a 3- mu m p-well CMOS process. The flexibility of the designed and tested circuits was confirme

CMOS design of chaotic oscillators using state variables: a monolithic Chua's circuit

This paper presents design considerations for monolithic implementation of piecewise-linear (PWL) dynamic systems in CMOS technology. Starting from a review of available CMOS circuit primitives and their respective merits and drawbacks, the paper proposes a synthesis approach for PWL dynamic systems, based on state-variable methods, and identifies the associated analog operators. The GmC approach, combining quasi-linear VCCS's, PWL VCCS's, and capacitors is then explored regarding the implementation of these operators. CMOS basic building blocks for the realization of the quasi-linear VCCS's and PWL VCCS's are presented and applied to design a Chua's circuit IC. The influence of GmC parasitics on the performance of dynamic PWL systems is illustrated through this example. Measured chaotic attractors from a Chua's circuit prototype are given. The prototype has been fabricated in a 2.4- mu m double-poly n-well CMOS technology, and occupies 0.35 mm/sup 2/, with a power consumption of 1.6 mW for a +or-2.5-V symmetric supply. Measurements show bifurcation toward a double-scroll Chua's attractor by changing a bias current

Optimal Piecewise-Linear Approximation of the Quadratic Chaotic Dynamics

This paper shows the influence of piecewise-linear approximation on the global dynamics associated with autonomous third-order dynamical systems with the quadratic vector fields. The novel method for optimal nonlinear function approximation preserving the system behavior is proposed and experimentally verified. This approach is based on the calculation of the state attractor metric dimension inside a stochastic optimization routine. The approximated systems are compared to the original by means of the numerical integration. Real electronic circuits representing individual dynamical systems are derived using classical as well as integrator-based synthesis and verified by time-domain analysis in Orcad Pspice simulator. The universality of the proposed method is briefly discussed, especially from the viewpoint of the higher-order dynamical systems. Future topics and perspectives are also provide

Derivation of linearized transfer functions for switching-mode regulations. Phase A: Current step-up and voltage step-up converters

Small-signal models are derived for the power stage of the voltage step-up (boost) and the current step-up (buck) converters. The modeling covers operation in both the continuous-mmf mode and the discontinuous-mmf mode. The power stage in the regulated current step-up converter on board the Dynamics Explorer Satellite is used as an example to illustrate the procedures in obtaining the small-signal functions characterizing a regulated converter

OTA-based non-linear function approximations

The suitability of operational transconductance amplifiers (OTAs) as the main active element to obtain basic building blocks for the design of programmable nonlinear continuous-time networks is examined. The main purpose is to show that the OTA, as the active element in basic building blocks, can be efficiently used for nonlinear continuous-time function synthesis. Two efficient nonlinear function synthesis approaches are presented. The first approach is a rational approximation, and the second is a piecewise-linear approach. Test circuits have been integrated using a 3-μm p-well CMOS process. The flexibility of the designed and tested circuits is confirmed

Current-mode piecewise-linear function generators

We present a systematic design technique for current-mode piecewise-linear (PWL) function generators. It uses two building blocks: a high-resolution current rectifier, and a programmable current amplifier. We show how to arrange these blocks to obtain basic non-linearities from which generic characteristics are built through aggregations. Measurements from a 1.0 /spl mu/m CMOS prototype chip show 10 pA resolution in the rectification operation and 0.6% non-linearity errors in the programmable scaling operation for 2 /spl mu/A input current range

A describing function for resonantly commutated H-bridge inverters

Abstract—The paper presents the derivation of a describing function to model the dynamic behavior of a metal oxide semiconductor field effect transistor-based, capacitively commutated H-bridge, including a comprehensive explanation of the various stages in the switching cycle. Expressions to model the resulting input current, are also given. The derived model allows the inverter to be accurately modeled within a control system simulation over a number of utility input voltage cycles, without resorting to computationally intensive switching-cycle level, time-domain SPICE simulations. Experimental measurements from a prototype H-bridge inverter employed in an induction heating application, are used to demonstrate a high degree of prediction accuracy over a large variation of load conditions is possible using the simplified model