Design and application of precise analog computational circuits

Abstract

New versatile building blocks for implementing analog functional circuits such as a multiplier, a squarer, and a square rooter based on functional terms of a differential input circuit are proposed and implemented in 0.25 um CMOS process. The input range of these circuits is over ±1.0 V with a high linearity of less than 4% for 3.3 V power supply. The -3 dB bandwidth of all discussed circuits has been measured to over 200 MHz. The functional circuit size is 340 lm 2 , and its typical power consumption is about 90 uW.

CMOS Current-Mode Implementation of Fractional-Power Functions

“…In [12], an adding resistance was applied to a quadratic-translinear circuit, to reduce errors caused by second order effects, where the resistance was replaced by 15 transistors. In [18], a circuit with a high input range, from −1 V to +1 V, and with 2.5% linearity error was implemented in a 0.25 µm CMOS process. However, references [12] and [18] focus on squarerooting applications.…”

“…In [18], a circuit with a high input range, from −1 V to +1 V, and with 2.5% linearity error was implemented in a 0.25 µm CMOS process. However, references [12] and [18] focus on squarerooting applications. In [14], a fuzzy logic controller with rational-powers from 0.125 to 4, with 1.32% RMS error is proposed.…”

“…A current-mode square-rooting circuit is an easily assembled fractional-power circuit, with applications in fuzzy linguistic-hedge circuits [3,4], adaptive filters [5,8], geometric mean circuits [2,10], and analog multipliers [18]. CMOS current-mode square-rooting circuits can operate on a quadratic-translinear principle [2,21], and recent applications employing the translinear principle include a notch filter [6], highprecision current-mode circuits [12], and a square-rooting circuit with selectable inputs (voltage or current) [17].…”

High-Precision CMOS Analog Computational Circuits Based on a New Linearly Tunable OTA

“…which are widely used in disk drives [1], hearing aids [2], medical equipment [3], modulators [4], artificial neural networks [5] and fuzzy control systems [6]. There are a lot of techniques to implement analog functional circuits [7][8][9][10][11][12][13][14][15][16][17][18] which can be roughly categorized in three main groups.…”

“…In this method the cause of error originates from the nonzero values of the base currents and of the temperature dependence of the bipolar transistor parameters (the thermal voltage is linearly increasing with temperature and the saturation current has an exponential dependence on temperature). In CMOS technology, TL principle relies on the exploiting of loop transistors operating either in weak inversion [9], [10] or strong inversion [11], [12]. For weak inversion, although it leads to circuits offering low power consumption, the dynamic range and the operation speed turn out to be limited.…”