Dynamic translinear RMS-DC converter - Electronics Letters

Introduction: One of the possible techniques to cope with the restrictions imposed by llow supply voltages is instantaneous companding [l], which is an inherent characteristic of translinear (TL) filters [2], also called exponential state-space filters [3]. TL filters exploit the exponential large-signal behaviour of the bipolar, or weak inversion MOS, transistor both for an expanding capacitance voltage to output-current conversion and to implement nultiplications of currents, based on the translinear principle [4]. Since TL loops are the basic elements of these filters, we propose the term: dynamic translinear principle, thus emphasising that translinear dynamic circuits ,are an extension of the conventional, i.e. static, translinear principle proposed by Gilbert [4]. TL filters inherit the advantages of conventional TL circuits: insensitivity to variations in temperature and processing, current controllability, large bandwidth and high functional density [5]. Another important chlaracteristic of TL circuits is that they can implement nonlinear trainsfer functions. Extending this to dynamic TL circuits implies that it will be possible to implement not only linear dynamic transfer functions, i.e. filters, but also nonlinear dynamics. Consequently, the dynamic translinear principle can be used to implement circuits ranging from filters to oscillators and even PLLs and chaotic circuits.