Current-mode Euclidean distance circuit independent on technological parameters

An Analog Template-Based Classifier Using MOS Translinear Loops

“…In the presented synthesis, the number of basic building blocks is severely reduced, and it just comprises simple two-quadrant squarer/divider unit [8,9] as the fundamental unit. Therefore, the system complexity of the proposed system is much less than those reported before [3][4][5][6]. The full parallel property of the system reduces the identification time and lead to a very regular structure.…”

“…In other words, the Euclidean distance is a direct measure of similarity between the template vectors that is closest to an input vector, in the sense that among a finite set of reference vectors, the least distant one from the input is the most similar to the input. Therefore, Euclidean distance is useful in classification algorithm [3][4][5][6]. The Euclidean distance between two n-dimensional vectors…”

“…An attractive method to implement classification algorithm is employing Euclidean distance calculator. Recently, some analog integrated forms of Euclidean distance calculator have been proposed [1][2][3][4][5][6]. They can be used in classifications algorithms to measure how close an input pattern is to the prototype patterns.…”

“…In current-mode processing the input signals which are mostly in current domain are nonlinearly transformed to the compressed voltage signal domain. Taking advantages of the current mode approach, Euclidean distance calculator circuits were proposed in current mode [3][4][5][6]. In these proposals, Euclidean distance calculator circuit has been performed by several basic building blocks, such as geometric-mean, squarer/divider, absoluter, and subtracter.…”

“…In these proposals, Euclidean distance calculator circuit has been performed by several basic building blocks, such as geometric-mean, squarer/divider, absoluter, and subtracter. For design of these functions, stacked translinear loop [3][4][5] or class-AB linear transconductors [6] have been employed. The main drawbacks of theses proposed circuits are as follows: firstly, these circuits operate in only one-quadrant input current that means the extra needed functions for full-wave rectification is needed; secondly, the extra needed functions lead to a large number of transistors and high power consumption; thirdly, the body effect of translinear MOSFETs in the squarer/divider block decreases the accuracy; finally, in these circuits due to the stacking of gate-source voltage of MOS transistors, they are often not well suited to lowvoltage operation.…”