Energy Consumption Estimation in Embedded Systems

This paper presents an energy consumption modeling technique for embedded systems based on a microcontroller. The software tasks that run on the embedded system are profiled, and their characteristics are analyzed. The type of executed assembly instructions, as well as the number of accesses to the memory and the analog-to-digital converter, is the required information for the derivation of the proposed model. An appropriate instrumentation setup has been developed for measuring and modeling the energy consumption in the corresponding digital circuits.     

A phase locked motor speed control system with sample-and-holdphase detector

A phase-locked speed-control with a sample-and-hold phase detector, which replaces the common phase detector and lowpass filter thus reducing the system's response time, is investigated. The phase detector's nonlinear behavior when operating inside the loop is discussed, together with the related lower speed limit. The system's operating region is determined by calculating the phase-locked loop (PLL) hold-in range and control system stability limits. Analytical expressions, along with related diagrams, illustrate the role of each of the system, parameters. Minimum system speed is also considered and its improvement through the use of various compensating networks is examined     

Analysis of unlocked and acquisition operation of a phase-lockedspeed control system

A study of a phase-locked speed control system is presented for a PM DC motor, focusing on the out-of-lock operation. System behavior is discussed for each case, while acquisition operation is described by phase plane analysis and capture mechanism is explained. Experimental results for a system developed are also given     

A simple analog division scheme

A technique for analog division of two voltage signals that offers high accuracy (0.5%) and relatively good response, especially when the numerator value is nearly constant, is presented. The proposed method is based on the relation of a signal's frequency to its period. The basic idea is to convert input voltage to frequency (through a voltage-controlled oscillator (VCO)) and then produce an output voltage proportional to the period of this signal. The circuit implementing this method is easy to build and may be used in many instrumentation and control applications where the reciprocal of a voltage is needed. Supporting experimental results and performance measurements are also given     

Design and applications of an easily integrable CMOS operational floating amplifier for the MegaHertz range

The design and major applications of a general purpose current mode building block are presented in this paper. This circuit is basically a high gain transconductance scheme with differential current output terminals previously termed operational floating amplifier (OFA). The novel structure proposed here is shown to implement a very flexible and high performance amplifier which can be used in almost all applications employing conveyors, current feedback amplifiers or even conventional operational amplifiers with improved performance characteristics. This presentation is also supported by experimental measurements on a prototype circuit realized in CMOS technology.     

Teaching instrumentation and measurement in the complex-systems era

It is critical to balance the need to convey fundamentals while delivering the essentials of modern instrumentation practice. This article presents a rather personal view on the challenges of I&M education in the context of rapid technological progress     

Cost-effective smart power CMOS/DMOS technology: design of main driving and protection functions

This paper intends to show that even with a CMOS technology main driving and protection functions of a power VDMOS can be made performant. Original circuits taking advantage of the availibility of the parasitic vertical bipolar transistor are presented and experimentally evaluated. A current mode approach is proposed to improve the accuracy of the current sensing function aimed at performing overcurrent, short-circuit and open-load detection.     

A current-mode interface circuit for a piezoresistive pressuresensor

An interfacing circuit for piezoresistive pressure sensors based on CMOS current conveyors is presented. The main advantages of the proposed interfacing circuit include the use of a single piezoresistor, the capability of offset compensation, and a versatile current-mode configuration, with current output and current or voltage input. Experimental tests confirm linear relation of output voltage versus piezoresistance variation     

Improving sensitivity and selectivity of SnO/sub 2/ gas sensors by temperature variation

A microcontroller-based gas-sensing system is presented in this paper. The analysis presented here exploits the differences in the steady-state performance of SnO/sub 2/ gas sensors at different operating temperatures and the potential use of such differences for improving their selectivity and sensitivity. Sets of experimental measurements of sensitivity versus temperature are used for the detailed presentation of the proposed approach. The results indicate that selective identification and rather accurate measurement of a mixture of CH/sub 4/ and CO gases are quite possible. Finally, a microcontroller-based configuration is presented as a working example of a small-size implementation, which may offer measurements of improved sensitivity and selectivity along with high accuracy and reliability.