This chapter covers device and circuit aspects of low-power analog CMOS circuit design. The fundamental limits constraining the design of low-power circuits are first recalled with an emphasis on the implications of supply voltage reduction. Biasing MOS transistors at very low current provides new features but requires dedicated models valid in all regions of operation including weak, moderate and strong inversion. Low-current biasing also has a strong influence on noise and matching properties. All these issues are discussed, together with the particular aspects related to passive devices and parasitic effects. The design process has to be supported by efficient and accurate circuit simulation. To this end, the EKV compact MOST model for circuit simulation is shortly presented. The use of the basic concepts such as pinch-off voltage, inversion factor and specific current are highlighted thanks to some very simple but fundamental circuits and to an effective use of the model. New design techniques that are appropriate for low-power and/or low-voltage circuits are presented with an emphasis on the analog floating point technique, the instantaneous companding principle, and their application to filters.

Translinear or log-domain #lters are theoretically exact realisations of linear di#erential equations. However, the dynamical translinear principle can also be applied to the implementation of nonlinear di#erential equations. In this paper, an RMS-DC converter is proposed, comprising a direct implementation of the corresponding nonlinear di#erential equation by means of the dynamical translinear principle. Correct operation of the circuit was veri#ed through measurements. 1 Introduction The translinear principle #1# plays a key role in conventional implementations of RMS-to-DC conversion #2#. A well-known RMS-DC converter is shown in Fig. 1. The squarer-divider basically comprises a four-transistor, i.e. second-order #3#, translinear loop. As the squarer-divider facilitates one-quadrant operation, its input signal is full-wave recti#ed. It calculates the current I 2 in =I out , where I out is the output current of the RMS-DC converter and is equal to the mean value of I 2 in ...

This paper presents an experimental discrete-component implementation of a syllabic companding audio-frequency continuoustime filter. Design considerations are provided for the effective implementation of such systems. Experimental results are given to support the proposed techniques. 1.

Abstract—Certain issues in the analysis of the effects of noise and interference in instantaneously companding signal processors is discussed. Important differences from the analysis and effects encountered in conventional signal processors are pointed out, and are illustrated by deriving analytical results for deterministic small interference and stationary random noise in a first-order instantaneously companding filter. The theoretical calculations are successfully compared to experimental results. Index Terms—Companding, noise, log-domain filters. I.

Low energy drain is key to the success of portable, battery-operated equipment. If the energy drain per task can be slashed down, battery life can proportionately be increased. Most conventional analog circuits are designed worst-case, for adequate performance while handling the most demanding tasks. This requires large power dissipation; when these circuits are called to perform less demanding tasks, they continue to dissipate the same large power unnecessarily. In other words, in such cases we are stuck with a fixed circuit. The solution is to allow the internal attributes of the circuit to vary, depending on the task at hand. In this article we review several recently proposed techniques that make this possible. We call these circuits internally varying. (We cannot call these circuits Y. Tsividis, N. Krishnapura,

In this thesis a new signal processing technique is presented. This technique exploits the use of pulses as the signalling mechanism. This Palmo 1 signalling method applied to signal processing is novel, combining the advantages of both digital and analogue techniques. Pulsed signals are robust, inherently low-power, easily regenerated, and easily distributed across and between chips. The Palmo cells used to perform analogue operations on the pulsed signals are compact, fast, simple and programmable.

doi:10.3906/elk-0904-11 A novel square-root domain realization of first order all-pass filter